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Hypertrophic cardiomyopathy (HCM) is characterized by thickening of the ventricular muscle without dilation and is often associated with dominant pathogenic variants in cardiac sarcomeric protein genes. Here, we report a family with two infants diagnosed with infantile-onset HCM and mitral valve dysplasia that led to death before one year of age. Using exome sequencing, we discovered that one of the affected children had a homozygous frameshift variant in Myosin light chain 2 (MYL2:NM_000432.3:c.431_432delCT: p.Pro144Argfs*57;MYL2-fs), which alters the last 20 amino acids of the protein and is predicted to impact the most C-terminal of the three EF-hand domains in MYL2. The parents are unaffected heterozygous carriers of the variant and the variant is absent in control cohorts from gnomAD. The absence of the phenotype in carriers and the infantile presentation of severe HCM is in contrast to HCM associated with dominant MYL2 variants. Immunohistochemical analysis of the ventricular muscle of the deceased patient with the MYL2-fs variant showed a marked reduction of MYL2 expression compared to an unaffected control. In vitro overexpression studies further indicate that the MYL2-fs variant is actively degraded. In contrast, an HCM-associated missense variant (MYL2:p.Gly162Arg) and three other MYL2 stop-gain variants (p.E22*, p.K62*, p.E97*) that result in loss of the EF domains are stably expressed but show impaired localization. The degradation of the MYL2-fs can be rescued by inhibiting the cell’s proteasome function supporting a post-translational effect of the variant. In vivo rescue experiments with a Drosophila MYL2-homolog (Mlc2) knockdown model indicate that neither the MYL2-fs nor the MYL2:p.Gly162Arg variant supports normal cardiac function. The tools that we have generated provide a rapid screening platform for functional assessment of variants of unknown significance in MYL2. Our study supports an autosomal recessive model of inheritance for MYL2 loss-of-function variants in infantile HCM and highlights the variant-specific molecular differences found in MYL2-associated cardiomyopathy., Author summary We report a novel frameshift variant in MYL2 that is associated with a severe form of infantile-onset hypertrophic cardiomyopathy. The impact of the variant is only observed in the recessive form of the disease found in the proband and not in the parents who are carriers of the variant. This contrasts with other dominant variants in MYL2 that are associated with cardiomyopathies. We compared the stability of this variant to that of other cardiomyopathy associated MYL2 variants and found molecular differences that correlated with disease pathology. We also show different protein domain requirements for stability and localization of MYL2 in cardiomyocytes. Furthermore, we used a fly model to demonstrate functional deficits due to the variant in the developing heart. Overall, our study shows a molecular mechanism by which loss-of-function variants in MYL2 are recessive while missense variants are dominant. We highlight the use of exome sequencing and functional testing to assist in the diagnosis of rare forms of disease where pathogenicity of the variant is not obvious. The new tools we developed for in vitro functional study and the fly fluorescent reporter analysis will permit rapid analysis of MYL2 variants of unknown significance.

Mitral valve construction using decellularized bovine pericardium is a new procedure. A 10-month-old infant with neonatal Marfan syndrome underwent mitral valve replacement due to severe mitral regurgitation with a cylinder valve constructed from decellularized bovine pericardium. Nineteen months postoperatively the patient is clinically well with trivial mitral regurgitation, mild stenosis, and without need for anticoagulation.

We present evidence from diverse disciplines and populations to identify the current and emerging role of genomics in prevention from both medical and public health perspectives as well as key challenges and potential untoward consequences of increasing the role of genomics in these endeavors. We begin by comparing screening in healthy populations (newborn screening), with testing in symptomatic populations, which may incidentally identify secondary findings and at-risk relatives. Emerging evidence suggests that variants in genes subject to the reporting of secondary findings are more common than expected in patients who otherwise would not meet the criteria for testing and population testing for variants in these genes may more precisely identify discrete populations to target for various prevention strategies starting in childhood. Conversely, despite its theoretical promise, recent studies attempting to demonstrate benefits of next-generation sequencing for newborn screening have instead demonstrated numerous barriers and pitfalls to this approach. We also examine the special cases of pharmacogenomics and polygenic risk scores as examples of ways genomics can contribute to prevention amongst a broader population than that affected by rare Mendelian disease. We conclude with unresolved questions which will benefit from future investigations of the role of genomics in disease prevention.

Genetic testing is important to augment clinical diagnosis and inform management of inherited arrhythmias syndromes (IAS), but variants of uncertain significance (VUS) are common and remain a challenge in clinical practice. In 2015, American College of Medical Genetics (ACMG) published updated guidelines for interpretation of genetic results. Despite increasing understanding of human genomic variation, there are no guidelines for reinterpretation of prior genetic test results. Patients at a single tertiary children's hospital with genetic testing for an IAS that demonstrated a VUS were re-evaluated using 2015 ACMG guidelines, clinical information, and publically available databases. Search of the electronic medical record identified 116 patients with genetic testing results available, and 24/116 (21%) harbored a VUS for an IAS. 23 unique VUS were evaluated from 12 genes. Over half of the VUS (12/23 (52%)) were reclassified using 2015 criteria, and 8 (35%) changed to pathogenic and 4 (17%) to benign. Relative risk of reclassification of VUS to a pathogenic variant in a patient with confirmed clinical diagnosis was 4.1 (95% CI 1.23-15.4). Reclassification was not associated with initial testing year. These data demonstrate 52% of VUS in children with IAS are reclassified with application of 2015 ACMG guidelines. Strength of phenotyping is associated with eventual pathogenic classification of genetic variants and periodic re-evaluation of VUS identified on genetic testing for IAS is warranted.

Background Neurodevelopmental disorders are genetically and phenotypically heterogeneous encompassing developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASDs), structural brain abnormalities, and neurological manifestations with variants in a large number of genes (hundreds) associated. To date, a few de novo mutations potentially disrupting TCF20 function in patients with ID, ASD, and hypotonia have been reported. TCF20 encodes a transcriptional co-regulator structurally related to RAI1, the dosage-sensitive gene responsible for Smith–Magenis syndrome (deletion/haploinsufficiency) and Potocki–Lupski syndrome (duplication/triplosensitivity). Methods Genome-wide analyses by exome sequencing (ES) and chromosomal microarray analysis (CMA) identified individuals with heterozygous, likely damaging, loss-of-function alleles in TCF20. We implemented further molecular and clinical analyses to determine the inheritance of the pathogenic variant alleles and studied the spectrum of phenotypes. Results We report 25 unique inactivating single nucleotide variants/indels (1 missense, 1 canonical splice-site variant, 18 frameshift, and 5 nonsense) and 4 deletions of TCF20. The pathogenic variants were detected in 32 patients and 4 affected parents from 31 unrelated families. Among cases with available parental samples, the variants were de novo in 20 instances and inherited from 4 symptomatic parents in 5, including in one set of monozygotic twins. Two pathogenic loss-of-function variants were recurrent in unrelated families. Patients presented with a phenotype characterized by developmental delay, intellectual disability, hypotonia, variable dysmorphic features, movement disorders, and sleep disturbances. Conclusions TCF20 pathogenic variants are associated with a novel syndrome manifesting clinical characteristics similar to those observed in Smith–Magenis syndrome. Together with previously described cases, the clinical entity of TCF20-associated neurodevelopmental disorders (TAND) emerges from a genotype-driven perspective. Electronic supplementary material The online version of this article (10.1186/s13073-019-0623-0) contains supplementary material, which is available to authorized users.

Proteoglycans have a core polypeptide connected to glycosaminoglycans (GAGs) via a common tetrasaccharide linker region. Defects in enzymes that synthesize the linker result in a group of autosomal recessive conditions called “linkeropathies”. Disease manifests with skeletal and connective tissue features, including short stature, hyperextensible skin, and joint hypermobility. We report a family with three affected pregnancies showing short limbs, cystic hygroma, and perinatal death. Two spontaneously aborted; one survived 1 day after term delivery, and had short limbs, bell-shaped thorax, 11 ribs, absent thumbs, and cleft palate. Exome sequencing of the proband and one affected fetus identified compound heterozygous missense variants, NM_007255.3: c.808C>T (p.(Arg270Cys)) and NM_007255.3: c.398A>G (p.(Gln133Arg)), in B4GALT7, a gene required for GAG linker biosynthesis. Homozygosity for p.(Arg270Cys), associated with partial loss of B4GALT7 function, causes Larsen of Reunion Island syndrome (LRS), however no previous studies have linked p.(Gln133Arg) to disease. The p.(Gln133Arg) and p.(Arg270Cys) variants were transfected into CHO pgsB-618 cells. High protein expression of p.(Gln133Arg) was found, with mislocalization, compared to p.(Arg270Cys) that had a normal Golgi-like pattern. The p.(Gln133Arg) had almost no enzyme activity and little production of heparan sulfate GAGs, while p.(Arg270Cys) only had 17% of wild-type activity. These findings expand the phenotype of B4GALT7-related linkeropathies to include lethal skeletal dysplasia due to more severe loss of function.

Wolf–Hirschhorn syndrome (WHS) is a rare but recurrent microdeletion syndrome associated with hemizygosity of an interstitial segment of Chromosome 4 (4p16.3). Consistent with historical reports in which overlapping deletions defined a minimal critical region in WHS patients, recent reports from exome sequence analysis have provided further evidence that haploinsufficiency of a specific gene within this critical region, NSD2 (WHSC1), is causal for many features of the syndrome. In this report, we describe three unrelated patients with loss-of-function alterations in NSD2 who presented clinically with WHS features including intrauterine growth retardation and global developmental delay. Two of the three patients also had overlapping features of failure to thrive, short stature, constipation, and hypotonia. This series adds additional cases to expand the phenotypic spectrum of WHS and reports novel NSD2 variants.

The mucopolysaccharidoses (MPS) are a genetically heterogenous group of enzyme deficiencies marked by accumulation of glycosaminoglycans in lysosomes leading to multisystem disease. Although significant therapeutic advances have been made for the MPS disorders, including recombinant enzyme replacement approaches, the neuronopathic features of MPS lack adequate treatment. Gene therapies, including adeno-associated virus vectors targeting the central nervous system, hold significant promise for this group of disorders. Optimal outcomes of all therapies will require early disease identification and treatment, ideally by newborn screening.

Background— Congenital heart disease (CHD) is the most common type of birth defect with family- and population-based studies supporting a strong genetic cause for CHD. The goal of this study was to determine whether a whole exome sequencing (WES) approach could identify pathogenic-segregating variants in multiplex CHD families. Methods and Results— WES was performed on 9 kindreds with familial CHD, 4 with atrial septal defects, 2 with patent ductus arteriosus, 2 with tetralogy of Fallot, and 1 with pulmonary valve dysplasia. Rare variants (GATA4 mutation in the transactivation domain, p.G115W, was identified in familial atrial septal defects and demonstrated decreased transactivation ability in vitro. A p.I263V mutation in TLL1 was identified in an atrial septal defects kindred and is predicted to affect the enzymatic functionality of TLL1. A disease-segregating splice donor site mutation in MYH11 (c.4599+1delG) was identified in familial patent ductus arteriosus and found to disrupt normal splicing of MYH11 mRNA in the affected individual. Conclusions— Our findings demonstrate the clinical utility of WES to identify causative mutations in familial CHD and demonstrate the successful use of a CHD candidate gene list to allow for a more streamlined approach enabling rapid prioritization and identification of likely pathogenic variants from large WES data sets. Clinical Trial Registration— URL: https://clinicaltrials.gov ; Unique Identifier: NCT0112048.

No treatment is currently available for mucopolysaccharidosis (MPS) IIIB, a neuropathic lysosomal storage disease due to defect in α-N-acetylglucosaminidase (NAGLU). In preparation for a clinical trial, we performed an IND-enabling GLP-toxicology study to assess systemic rAAV9-CMV-hNAGLU gene delivery in WT C57BL/6 mice at 1 × 10(14) vg/kg and 2 × 10(14) vg/kg (n = 30/group, M:F = 1:1), and non-GLP testing in MPS IIIB mice at 2 × 10(14) vg/kg. Importantly, no adverse clinical signs or chronic toxicity were observed through the 6 month study duration. The rAAV9-mediated rNAGLU expression was rapid and persistent in virtually all tested CNS and somatic tissues. However, acute liver toxicity occurred in 33% (5/15) WT males in the 2 × 10(14) vg/kg cohort, which was dose-dependent, sex-associated, and genotype-specific, likely due to hepatic rNAGLU overexpression. Interestingly, a significant dose response was observed only in the brain and spinal cord, whereas in the liver at 24 weeks postinfection (pi), NAGLU activity was reduced to endogenous levels in the high dose cohort but remained at supranormal levels in the low dose group. The possibility of rAAV9 germline transmission appears to be minimal. The vector delivery resulted in transient T-cell responses and characteristic acute antibody responses to both AAV9 and rNAGLU in all rAAV9-treated animals, with no detectable impacts on tissue transgene expression. This study demonstrates a generally safe and effective profile, and may have identified the upper dosing limit of rAAV9-CMV-hNAGLU via systemic delivery for the treatment of MPS IIIB.

Wilson disease is a medically actionable rare autosomal recessive disorder of defective copper excretion caused by mutations in ATP7B, one of two highly evolutionarily conserved copper-transporting ATPases. Hundreds of disease-causing variants in ATP7B have been reported to public databases; more than half of these are missense changes, and a significant proportion are presumed unequivocal loss-of-function variants (nonsense, frameshift, and canonical splice site). Current molecular genetic testing includes sequencing all coding exons (±10 bp) as well as deletion/duplication testing, with reported sensitivity of >98%. We report a proband from a consanguineous family with a biochemical phenotype consistent with early-onset Wilson disease who tested negative on conventional molecular genetic testing. Using a combination of whole-genome sequencing and transcriptome sequencing, we found that the proband's disease is due to skipping of exons 6–7 of the ATP7B gene associated with a novel intronic variant (NM_000053.4:c.1947-19T > A) that alters a putative splicing enhancer element. This variant was also homozygous in the proband's younger sister, whose subsequent clinical evaluations revealed biochemical evidence of Wilson disease. Our work adds to emerging evidence that ATP7B exon skipping from deep intronic variants outside typical splice junctions is an important mechanism of Wilson disease; the variants responsible may elude standard genetic testing.

A 4-yr-old female with congenital knee dislocations and joint laxity was noted to have a strong maternal family history comprising multiple individuals with knee problems and clubfeet. As the knee issues were the predominant clinical features, clinical testing included sequencing of LMX1B, TBX2, and TBX4, which identified no significant variants. Research genome sequencing was performed in the proband, parents, and maternal grandfather. A heterozygous in-frame deletion in FLNB c. 5468_5470delAGG, which predicts p.(Glu1823del), segregated with the disease. The variant is rare in the gnomAD database, removes a residue that is evolutionarily conserved, and is predicted to alter protein length. Larsen syndrome may present with pathology that primarily involves one joint and thus may be difficult to differentiate clinically from other skeletal dysplasias or arthrogryposis syndromes. The p.(Glu1823del) variant maps to a filamin repeat domain where other disease-causing variants are clustered, consistent with a probable gain-of-function mechanism. It has reportedly been observed in two individuals in the gnomAD database, suggesting that mild presentations of Larsen syndrome, like the individual reported here, may be underdiagnosed in the general population.

Purpose: Maternal phenylketonuria (MPKU) requires strict control of phenylalanine (Phe) and supplemental tyrosine (Tyr). Monitoring during pregnancy using dried blood spot (DBS) cards by tandem mass spectrometry (MS/MS) is now standard practice, however there are no Phe and Tyr reference ranges for DBS MS/MS method in healthy pregnant women. Methods: DBS cards (63 −1364 days in storage) from healthy women with singleton pregnancies were analyzed by MS/MS. 390 DBS cards from 170 pregnancies (5/1–39/6 weeks’ gestation), were tested. Results: Both Phe and Tyr levels declined from the first trimester (Phe: 36.2 +/− 10.6; Tyr 25.7 +/−9.7 micromol/L) to the second trimester (Phe 33.4 +/− 9.3; Tyr 21.7 +/− 6.7 micromol/L) and remained stable in the third trimester (Phe 32.3 +/− 8.7; Tyr 21.0 +/− 6.6 micromol/L). Phe and Tyr levels declined over time since collection (Phe: 0.004 micromol/L per day; Tyr 0.002 micromol/L). Nomograms by gestational age were created using raw data and data adjusted for time from sample collection. Reference ranges by trimester are provided. Conclusion: Both Phe and Tyr decline quickly during the first trimester and remain relatively constant over the second and third trimesters. These nomograms will provide a valuable resource for care of MPKU.

The purpose of this document is to provide updated guidance for the genetic evaluation of cardiomyopathy and for an approach to manage secondary findings from cardiomyopathy genes. The genetic bases of the primary cardiomyopathies (dilated, hypertrophic, arrhythmogenic right ventricular, and restrictive) have been established, and each is medically actionable; in most cases established treatments or interventions are available to improve survival, reduce morbidity, and enhance quality of life. A writing group of cardiologists and genetics professionals updated guidance, first published in 2009 for the Heart Failure Society of America (HFSA), in a collaboration with the American College of Medical Genetics and Genomics (ACMG). Each recommendation was assigned to teams of individuals by expertise, literature was reviewed, and recommendations were decided by consensus of the writing group. Recommendations for family history, phenotype screening of at-risk family members, referral to expert centers as needed, genetic counseling, and cardiovascular therapies, informed in part by phenotype, are presented in the HFSA document. A genetic evaluation of cardiomyopathy is indicated with a cardiomyopathy diagnosis, which includes genetic testing. Guidance is also provided for clinical approaches to secondary findings from cardiomyopathy genes. This is relevant as cardiomyopathy is the phenotype associated with 27% of the genes on the ACMG list for return of secondary findings. Recommendations herein are considered expert opinion per current ACMG policy as no systematic approach to literature review was conducted. Genetic testing is indicated for cardiomyopathy to assist in patient care and management of at-risk family members.

BACKGROUND: Mucopolysaccharidosis (MPS) type III, Sanfilippo Syndrome, is an autosomal recessive lysosomal storage disorder. MPS I and II patients often develop cardiac involvement leading to early mortality, however there are limited data in MPS III. The objective of this study is to describe cardiac abnormalities in a large group of MPS III patients followed in a longitudinal natural history study designed to determine outcome measures for gene transfer trials. METHODS: A single center study of MPS III patients who were enrolled in the Nationwide Children’s Hospital natural history study in 2014. Two cardiologists reviewed all patient echocardiograms for anatomic, valvular, and functional abnormalities. Valve abnormalities were defined as abnormal morphology, trivial mitral regurgitation (MR) with abnormal morphology or at least mild MR, and any aortic regurgitation (AR). Abnormal left ventricular (LV) function was defined as ejection fraction < 50%. Group comparisons were assessed using two-sample t-tests or Wilcoxon rank sum tests for continuous variables and chi-square or Fisher’s exact tests for categorical variables. RESULTS: Twenty-five patients, 15 Type A and 10 Type B MPS III, underwent 45 echocardiograms. Fifteen patients (60%) demonstrated an abnormal echocardiographic finding with age at first abnormal echocardiogram within the study being 6.8 ± 2.8years. Left-sided valve abnormalities were common over time: 7 mitral valve thickening, 2 mitral valve prolapse, 16 MR (8 mild, 8 trivial), 3 aortic valve thickening, and 9 AR (7 mild, 2 trivial). Two patients had asymmetric LV septal hypertrophy. No valvular stenosis or ventricular function abnormalities were noted. Incidental findings included: mild aortic root dilation (2), bicommissural aortic valve (1), and mild tricuspid regurgitation (3). CONCLUSIONS: Individuals with Sanfilippo A and B demonstrate a natural history of cardiac involvement with valvular abnormalities most common. In short-term follow up, patients demonstrated only mild progression of abnormalities, none requiring intervention. Valvular disease prevalence is similar to MPS I and II, but appears less severe. These findings raise no specific concerns for gene transfer trials in patients in this age range.

It was highlighted that the original article [1] contained a typographical error in the Results section. Subject 17 was incorrectly cited as Subject 1. This Correction article shows the revised statement. The original article has been updated.

Citrullinemia is a rare inborn error of urea cycle metabolism causing hyperammonemia. In the classic form, a newborn presents with poor feeding, vomiting, progressive lethargy and signs of increasing intracranial pressure 3–7 d after birth, rapidly progressing to apnea, coma and death if untreated. We found only two reported cases in the literature describing magnetic resonance imaging findings of neonatal citrullinemia. We present a case of neonatal citrullinemia with more extensive and asymmetric magnetic resonance imaging abnormalities, including evidence of both superficial and deep venous cerebral infarction.

Dilated cardiomyopathy (DCM) is a disease of the myocardium characterized by left ventricular dilatation and diminished contractile function. Here we describe a novel DCM mutation in the myosin regulatory light chain (RLC), in which aspartic acid at position 94 is replaced by alanine (D94A). The mutation was identified by exome sequencing of three adult first-degree relatives who met formal criteria for idiopathic DCM. To obtain insight into the functional significance of this pathogenic MYL2 variant, we cloned and purified the human ventricular RLC wild-type (WT) and D94A mutant proteins, and performed in vitro experiments using RLC-mutant or WT-reconstituted porcine cardiac preparations. The mutation induced a reduction in the α-helical content of the RLC, and imposed intra-molecular rearrangements. The phosphorylation of RLC by Ca²⁺/calmodulin-activated myosin light chain kinase was not affected by D94A. The mutation was seen to impair binding of RLC to the myosin heavy chain, and its incorporation into RLC-depleted porcine myosin. The actin-activated ATPase activity of mutant-reconstituted porcine cardiac myosin was significantly higher compared with ATPase of wild-type. No changes in the myofibrillar ATPase-pCa relationship were observed in wild-type- or D94A-reconstituted preparations. Measurements of contractile force showed a slightly reduced maximal tension per cross-section of muscle, with no change in the calcium sensitivity of force in D94A-reconstituted skinned porcine papillary muscle strips compared with wild-type. Our data indicate that subtle structural rearrangements in the RLC molecule, followed by its impaired interaction with the myosin heavy chain, may trigger functional abnormalities contributing to the DCM phenotype.

Congenital heart disease (CHD) is one of the most common groups of birth defects,1 contributing to a major portion of mortality in early childhood and consuming large amounts of healthcare and family resources. They have a birth prevalence of 6 to 8/1000 live births, excluding late recognized defects, such as bicuspid aortic valve, which has a population frequency of 1% to 2%.1 See Article by Guo et al Genetic epidemiology studies and reports of multiple recurrences of CHDs within families demonstrate a strong genetic component. Familial clustering of CHDs is particularly apparent when grouped by developmental mechanism.2 A recent large study using hundreds of these multiplex families confirmed the concept of grouping CHD by developmental mechanism, and supporting animal data suggest that these groupings are because of perturbations of genetic networks important in cardiogenesis.3 Indeed, of all risk factors for CHD, a family history of CHD has the highest relative risk even over maternal diabetes mellitus or twinning.4 More formal segregation analyses have confirmed the strong genetic component, also noting that the inheritance pattern is likely complex and oligogenic.2 This evidence for the genetic basis of CHD spurred investigators to search for responsible loci and genes. A few early successes occurred using the traditional genetic approach of linkage, identifying pathogenic variants in NKX2-5 ,5 NOTCH1 ,6 and GATA4 7 among multiplex families with CHDs. Unfortunately, further successes have been scarce, with the exception of CHDs occurring as part of a syndrome (such as the RASopathies). Genome-wide association studies for specific groups of CHD have added a few more loci but with limited replications in a second study.8,9 Copy number variant studies have identified novel genomic disorders in as many as 20% of syndromic cases, a few percent of nonsyndromic …

Congenital left-sided cardiac lesions (LSLs) are a significant contributor to the mortality and morbidity of congenital heart disease (CHD). Structural copy number variants (CNVs) have been implicated in LSL without extra-cardiac features; however, non-penetrance and variable expressivity have created uncertainty over the use of CNV analyses in such patients. High-density SNP microarray genotyping data were used to infer large, likely-pathogenic, autosomal CNVs in a cohort of 1,139 probands with LSL and their families. CNVs were molecularly confirmed and the medical records of individual carriers reviewed. The gene content of novel CNVs was then compared with public CNV data from CHD patients. Large CNVs (>1 MB) were observed in 33 probands (∼3%). Six of these were de novo and 14 were not observed in the only available parent sample. Associated cardiac phenotypes spanned a broad spectrum without clear predilection. Candidate CNVs were largely non-recurrent, associated with heterozygous loss of copy number, and overlapped known CHD genomic regions. Novel CNV regions were enriched for cardiac development genes, including seven that have not been previously associated with human CHD. CNV analysis can be a clinically useful and molecularly informative tool in LSLs without obvious extra-cardiac defects, and may identify a clinically relevant genomic disorder in a small but important proportion of these individuals.

Marfan syndrome is a multisystem disease with cardiovascular, ophthalmologic, and skeletal features. Diagnosis is made clinically with emphasis on presence of aortic root dilation and ectopia lentis (EL). Most individuals meeting these criteria have a pathogenic variant in FBN1, usually unique or observed rarely. Individuals with EL alone may also have FBN1 pathogenic variants, and the risk for aortic disease is not well known. We identified a unique cohort of 31 individuals (mean age 29, range 2–78) from nine families ascertained by a proband with EL alone, who had the same FBN1 p.R650C variant. Comparison was made to individuals with Marfan syndrome (n = 103 from 97 families) at our institution. Those with the p.R650C variant had few skeletal features of Marfan syndrome. Age of onset of EL was later compared to others with cysteine variant changes. Aortic root dilation occurred in 4/16 (25%) of the p.R650C group versus 71/83 (86%) in the comparator group (p

Bicuspid aortic valve (BAV) is the most common type of congenital heart defect (CHD) and is associated with clinically significant cardiovascular complications including valve calcification and ascending aortopathy (AscAo), predominantly occurring in adulthood. While a limited number of genetic etiologies for BAV have been defined, family members of affected individuals display BAV along with other left-sided CHD. This has led to guidelines from the American Heart Association and American College of Cardiology that recommend echocardiographic screening of first-degree relatives of affected adults. While potentially beneficial in adults, the yield of such screening in children is unknown. The purpose of this study was to investigate a cohort of children with familial BAV to determine the frequency of development of AscAo, and to identify risk factors that contribute to abnormal aortic growth. Echocardiograms over a 10-year follow-up period were reviewed on 26 patients with familial BAV [22 male, 4 female; 22 with isolated BAV, 6 with BAV and aortic coarctation (CoA)]. All had a family history of CHD and were recruited from 2005 to 2010 as part of a genetics research study. Four aortic segments (annulus, root, sinotubular junction, ascending aorta) on parasternal long-axis echocardiographic images were measured by a single observer. The mean age at first echocardiogram was 7.1 ± 5.5 and that was 13.8 ± 6.2 years at the last echocardiogram. Only patients with > 2 echocardiograms in the 10-year period were included. Z score measurements of the aorta were plotted over time and based on these the cohort was divided into two groups: Group 1 (abnormal)—Z score for any segment > 2 or a change in Z score > 2 over follow-up; Group 2 (normal)—Z score

Clinical genetic testing for specific isolated congenital heart defects (CHD) is becoming standard of care in pediatric cardiology practice. Both genetic knowledge and attitudes toward genetic testing are associated with an increased utilization of genetic testing, but these factors have not been evaluated in parents of children with CHD. We mailed a survey to measure the demographics, genetic knowledge, and attitudes towards genetic testing of parents of children with CHD who previously consented to participate in a separate research study of the genetic etiology of left ventricular outflow tract malformations (LVOT). Of the 378 eligible families, 190 (50%) returned surveys with both parents completing surveys in 97 (51%) families, resulting in 287 participants. Genetic knowledge was assessed on an adapted measure on which the mean percent correct was 73.8%. Educational attainment and household income were directly and significantly associated with genetic knowledge (P 0.001). Attitudes about the health effects of genetic testing were favorable with at least 57% agreeing that genetic testing would be used for managing health care and finding cures for disease. Conversely, a minority of participants found it likely that genetic testing would be used for insurance (up to 39.9%), employment (15.8%), or racial/social discrimination (up to 11.2%). Parents of younger children were less likely to endorse employment or racial/social discrimination. Genetic knowledge was not correlated with specific attitudes. Among parents of children with CHD, genetic knowledge was directly associated with household income and education, but additional research is necessary to determine what factors influence attitudes towards genetic testing.

No treatment is currently available for mucopolysaccharidosis (MPS) IIIB, a neuropathic lysosomal storage disease caused by autosomal recessive defect in α-N-acetylglucosaminidase (NAGLU). In anticipation of a clinical gene therapy treatment for MPS IIIB in humans, we tested the rAAV9-CMV-hNAGLU vector administration to cynomolgus monkeys (n=8) at 1E13 vg/kg or 2E13 vg/kg via intravenous injection. No adverse events or detectable toxicity occurred over a 6-month period. Gene delivery resulted in persistent global central nervous system and broad somatic transduction, with NAGLU activity detected at 2.9-12-fold above endogenous levels in somatic tissues and 1.3-3-fold above endogenous levels in the brain. Secreted rNAGLU was detected in serum. Low levels of preexisting anti-AAV9 antibodies (Abs) did not diminish vector transduction. Importantly, high-level preexisting anti-AAV9 Abs lead to reduced transduction in liver and other somatic tissues, but had no detectable impact on transgene expression in the brain. Enzyme-linked immunoabsorbent assay showed Ab responses to both AAV9 and rNAGLU in treated animals. Serum anti-hNAGLU Abs, but not anti-AAV9 Abs, correlated with the loss of circulating rNAGLU enzyme. However, serum Abs did not affect tissue rNAGLU activity levels. Weekly or monthly peripheral blood interferon-γ enzyme-linked immunospot assays detected a CD4(+) T-cell (Th-1) response to rNAGLU only at 4 weeks postinjection in one treated subject, without observable correlation to tissue transduction levels. The treatment did not result in detectable CTL responses to either AAV9 or rNAGLU. Our data demonstrate an effective and safe profile for systemic rAAV9-hNAGLU vector delivery in nonhuman primates, supporting its clinical potential in humans.

Bicuspid aortic valve (BAV) is the most common type of congenital heart disease (CHD) and has a proposed genetic etiology. BAV is categorized by cusp fusion, with right-left (R-L) cusp fusion being associated with additional CHD, and right-noncoronary cusp (R-NC) fusion being associated with aortic valve dysfunction. Loss of murine Gata5, which encodes a cardiac transcription factor, results in a partially penetrant R-NC BAV, and we hypothesize that mutations in GATA5 are associated with R-NC BAV in humans. A cohort of 78 BAV patients (50 with isolated BAV and 28 with associated aortic coarctation) was analyzed using Sanger sequencing to identify GATA5 sequence variants. Biochemical assays were performed to identify functional deficits of identified sequence variants. We identified two rare heterozygous nonsynonymous variants, p.Gln3Arg and p.Leu233Pro, for a frequency of 2.6% (2/78). Both individuals with nonsynonymous variants had BAV and aortic coarctation, one R-L and one R-NC subtype. Of the nonsynonymous variants, only p.Gln3Arg demonstrated decreased transcriptional activity in vitro. Rare sequence variants in GATA5 are associated with human BAV. Our findings suggest a genotype–phenotype correlation in regards to associated CHD but not cusp fusion.

Prior research suggests that parents undervalue long-term risks associated with their children’s participation in research studies. The primary aim of this study was to evaluate parental understanding of informed consent for a pediatric biobanking study. The study population included parents who provided consent for their child to participate in a study examining the genetic etiology of congenital cardiovascular malformations. Informed consent understanding was measured by adapting the Quality of Informed Consent assessment to our study. We evaluated possible predictors of individual Quality of Informed Consent items using generalized estimating equations. A total of 252 individuals representing 188 families completed the study. The Quality of Informed Consent items best understood by parents included consent to participate in research, the main purpose of the study, and the possibility of no direct benefit. The items least understood by parents were those involving the indefinite storage of DNA, the possible risks of participation, and the fact that the study was not intended to treat their child’s heart defect. Parent age and medical decision making by one versus both parents were frequent predictors of individual Quality of Informed Consent items. Parents overestimate personal benefit and underestimate the risks associated with their child’s participation in a biobanking study. Genet Med 16 2, 141–148.

SummaryBackground Mucopolysaccharidosis type III is a progressive disease with worsening airway, pulmonary, and cardiac involvement that may complicate anesthetic care. Aim To prospectively evaluate the incidence of airway issues and complications during magnetic resonance imaging (MRI) and lumbar puncture (LP) during general anesthesia with a native airway for patients with mucopolysaccharidosis type III. Method The study was a part of the natural history study. Anesthesia was induced with sevoflurane, which was discontinued after intravenous access was obtained. General anesthesia with a native airway was provided by dexmedetomidine and propofol. Dexmedetomidine (0.5 μg·kg−1) was administered over 5 min followed by a continuous infusion at 0.5 μg·kg−1·h−1. A continuous infusion of propofol was started at 150 μg·kg−1·min−1. A bolus dose of propofol (1 mg·kg−1) was administered and the propofol infusion was increased as needed. Airway management and vital signs were recorded for the entire procedure until discharge. Results Twenty-five patients (6.9 ± 3.1 years) received total of 43 MRI and LP procedures in the cohort. No patient failed sedation. Although mask induction with sevoflurane was not clinically problematic, upper airway obstruction was noted during 14 procedures (33%). This required the application of continuous positive airway pressure, temporary oral airway placement, jaw thrust, or shoulder roll. Airway dynamics improved once the anesthesia was transitioned to intravenous anesthetic agents. Although a small shoulder roll was needed to improve airway patency for 11 cases (26%), a large shoulder roll tended to make the upper airway obstruction worse. Oxygen desaturation (≤90%) was noted during MRI in three cases (7%). Conclusion A combination of dexmedetomidine and propofol provided effective general anesthesia with a native airway during the procedures. Although upper airway obstruction was noted, it resolved with simple airway maneuvers without further airway intervention.

Wolf–Hirschhorn syndrome (WHS) is a rare but recurrent microdeletion syndrome associated with hemizygosity of an interstitial segment of Chromosome 4 (4p16.3). Consistent with historical reports in which overlapping deletions defined a minimal critical region in WHS patients, recent reports from exome sequence analysis have provided further evidence that haploinsufficiency of a specific gene within this critical region, NSD2 (WHSC1), is causal for many features of the syndrome. In this report, we describe three unrelated patients with loss-of-function alterations in NSD2 who presented clinically with WHS features including intrauterine growth retardation and global developmental delay. Two of the three patients also had overlapping features of failure to thrive, short stature, constipation, and hypotonia. This series adds additional cases to expand the phenotypic spectrum of WHS and reports novel NSD2 variants.

Coarctation of the aorta (CoA) and hypoplastic left heart syndrome (HLHS) have been reported in rare individuals with large terminal deletions of chromosome 15q26. However, no single gene important for left ventricular outflow tract (LVOT) development has been identified in this region. Using array-comparative genomic hybridization, we identified two half-siblings with CoA with a 2.2 Mb deletion on 15q26.2, inherited from their mother, who was mosaic for this deletion. This interval contains an evolutionary conserved, protein-coding gene, MCTP2 (multiple C2-domains with two transmembrane regions 2). Using gene-specific array screening in 146 individuals with non-syndromic LVOT obstructive defects, another individual with HLHS and CoA was found to have a de novo 41 kb intragenic duplication within MCTP2, predicted to result in premature truncation, p.F697X. Alteration of Mctp2 gene expression in Xenopus laevis embryos by morpholino knockdown and mRNA overexpression resulted in the failure of proper OT development, confirming the functional importance of this dosage-sensitive gene for cardiogenesis. Our results identify MCTP2 as a novel genetic cause of CoA and related cardiac malformations.

Recent studies have shown that certain copy number variations (CNV) are associated with a wide range of neurodevelopmental disorders, including autism spectrum disorders (ASD), bipolar disorder and intellectual disabilities. Implicated regions and genes have comprised a variety of post synaptic complex proteins and neurotransmitter receptors, including gamma-amino butyric acid A (GABAA). Clusters of GABAA receptor subunit genes are found on chromosomes 4p12, 5q34, 6q15 and 15q11-13. Maternally inherited 15q11-13 duplications among individuals with neurodevelopmental disorders are well described, but few case reports exist for the other regions. We describe a family with a 2.42 Mb duplication at chromosome 4p13 to 4p12, identified in the index case and other family members by oligonucleotide array comparative genomic hybridization, that contains 13 genes including a cluster of four GABAA receptor subunit genes. Fluorescent in-situ hybridization was used to confirm the duplication. The duplication segregates with a variety of neurodevelopmental disorders in this family, including ASD (index case), developmental delay, dyspraxia and ADHD (brother), global developmental delays (brother), learning disabilities (mother) and bipolar disorder (maternal grandmother). In addition, we identified and describe another individual unrelated to this family, with a similar duplication, who was diagnosed with ASD, ADHD and borderline intellectual disability. The 4p13 to 4p12 duplication appears to confer a susceptibility to a variety of neurodevelopmental disorders in these two families. We hypothesize that the duplication acts through a dosage effect of GABAA receptor subunit genes, adding evidence for alterations in the GABAergic system in the etiology of neurodevelopmental disorders.

Maternal phenylketonuria (MPKU) is a syndrome including cardiovascular malformations (CVMs), microcephaly, intellectual impairment, and small size for gestational age, caused by in-utero exposure to elevated serum phenylalanine (Phe) due to PKU in the mother. It is becoming a public health concern as more women with PKU reach child bearing age. Although a mouse model of PKU, BTBR Pah(enu2), has been available for 20 years, it has not been well utilized for studying MPKU. We used this model to delineate critical parameters in Phe cardiovascular teratogenicity and study the effect of genetic background. Dosing and timing experiments were performed with the BTBR Pah(enu2) mouse. A dose response curve was noted, with CVM rates at maternal serum Phe levels360 μM (control), 360-600 μM (low), 600-900 μM (mid), and900 μM (high) of 11.86%, 16.67%, 30.86%, and 46.67% respectively. A variety of CVMs were noted on the BTBR background, including double outlet right ventricle (DORV), aortic arch artery (AAA) abnormalities, and ventricular septal defects (VSDs). Timed exposure experiments identified a teratogenic window from embryonic day 8.5-13.5, with higher rates of conotruncal and valve defects occurring in early exposure time and persistent truncus arteriosus (PTA) and aortic arch branching abnormalities occurring with late exposure. Compared to the BTBR strain, N10+ Pah(enu2) congenics on the C3H/HeJ background had higher rates of CVMs in general and propensity to left ventricular outflow tract (LVOT) malformations, while the C57B/L6 background had similar CVM rates but predominately AAA abnormalities. We have delineated key parameters of Phe cardiovascular teratogenicity, demonstrated the utility of this MPKU model on different mouse strains, and shown how genetic background profoundly affects the phenotype.

Congenital heart defects involving left-sided lesions (LSLs) are relatively common birth defects with substantial morbidity and mortality. Previous studies have suggested a high heritability with a complex genetic architecture, such that only a few LSL loci have been identified. We performed a genome-wide case-control association study to address the role of common variants using a discovery cohort of 778 cases and 2756 controls. We identified a genome-wide significant association mapping to a 200 kb region on chromosome 20q11 [P= 1.72 × 10-8 for rs3746446; imputed Single Nucleotide Polymorphism (SNP) rs6088703 P= 3.01 × 10-9, odds ratio (OR)= 1.6 for both]. This result was supported by transmission disequilibrium analyses using a subset of 541 case families (lowest P in region= 4.51 × 10-5, OR= 1.5). Replication in a cohort of 367 LSL cases and 5159 controls showed nominal association (P= 0.03 for rs3746446) resulting in P= 9.49 × 10-9 for rs3746446 upon meta-analysis of the combined cohorts. In addition, a group of seven SNPs on chromosome 1q21.3 met threshold for suggestive association (lowest P= 9.35 × 10-7 for rs12045807). Both regions include genes involved in cardiac development-MYH7B/miR499A on chromosome 20 and CTSK, CTSS and ARNT on chromosome 1. Genome-wide heritability analysis using case-control genotyped SNPs suggested that the mean heritability of LSLs attributable to common variants is moderately high ([Formula: see text] range= 0.26-0.34) and consistent with previous assertions. These results provide evidence for the role of common variation in LSLs, proffer new genes as potential biological candidates, and give further insight to the complex genetic architecture of congenital heart disease.

Autism spectrum disorders (ASDs) are a heterogeneous and common group of developmental disorders. Affected infants and children demonstrate severe and persistent impairments in expressive and receptive language and social interaction skills that are evident before age 3, as well as a variety of stereotypic and repetitive behaviors. There is overwhelming scientific evidence demonstrating high heritability (≥90%) and a strong genetic component to the etiologies of autism (reviewed in [Abrahams & Geschwind, 2008]). However, identifiable causes, such as Fragile X syndrome and chromosome abnormalities, account for ≤10% of cases. It is estimated that 10 to >100 genes, in addition to environmental effects, may contribute to disease susceptibility. Recently, small de novo genomic rearrangements or copy number variations (CNVs), that are likely pathogenic, have been identified in an additional ~10% of ASD cases [Marshall et al., 2008; Sebat et al., 2007; Shen et al., 2010; Szatmari et al., 2007]. Selected inherited CNVs likely represent additional susceptibility loci [Marshall et al., 2008; Shen et al., 2010; Szatmari et al., 2007]. A unifying theme among many of the CNVs identified, as well as susceptibility loci ascertained by linkage and association studies and direct gene sequencing, is localization of the involved protein at neural synapses. Contactin 4 (CNTN4), also called BIG-2, is a member of the immunoglobulin (Ig) superfamily of axon-associated adhesion molecules. The structure for the six human contactins consists of an N-terminal signal peptide followed by 6 Ig-like and 4 fibronectin type III-like domains, and a C-terminal glycosylphosphatidylinositol (GPI) binding site that anchors the protein to the external surface of the plasma membrane [Shimoda & Watanabe, 2009]. Cell surface contactins complex with one or more of 5 human contactin-associated proteins (CNTNAPs) that are members of the neurexin gene family (reviewed in [Burbach & van der Zwaag, 2009; Katidou, Vidaki, Strigini, & Karagogeos, 2008]). These complexes are believed to participate in neuronal migration, axon guidance, and neuronal and glial cell interactions, with exact functions dependent on the developmental stage and exact localization of the interacting proteins. Recent research implicates contactins and contactin-associated proteins (CNTNAPs) in neurodevelopmental disorders, including autism. Linkage and association analyses [Alarcon et al., 2008; Arking et al., 2008], as well as deep resequencing [Bakkaloglu et al., 2008], identified CNTNAP2 as a susceptibility locus for autism. Homozygosity mapping identified a homozygous deletion in the 5′ UTR of CNTN3 (BIG-1) in an autistic individual from a consanguineous mating, further implicating this gene family [Morrow et al., 2008]. CNTN4 maps to 3p26.3 and is deleted in individuals with 3p− syndrome, a rare microdeletion syndrome associated with developmental delay/mental retardation, microcephaly, and characteristic facies [Fernandez et al., 2008; Malmgren, Sahlen, Wide, Lundvall, & Blennow, 2007]. The CNTN4 gene has been considered a strong candidate for the developmental delay and microcephaly associated with 3p− syndrome, based on its postulated role in neurodevelopment and its disruption in patients with features of 3p− syndrome and a balanced 3;10 or unbalanced 3;13 chromosome translocation, respectively [Fernandez et al., 2004; Fernandez et al., 2008]. Several studies performing molecular characterization of patients with 3p− syndrome have concluded that CNTN4 lies within the minimal critical region [Dijkhuizen et al., 2006; Malmgren et al., 2007]. However, in a more recent investigation, CNTN4 appears to be excluded from the critical region based on a single patient with an interstitial 3p26 deletion [Shuib et al., 2009]. In addition, rare phenotypically normal individuals have been reported with visible deletions involving 3p26 that include CNTN4 ([Pohjola, de Leeuw, Penttinen, & Kaariainen, 2010; Shuib et al., 2009] and references therein). More recently, an intragenic deletion within CNTN4 [Roohi et al., 2009] was reported in two siblings with an ASD and their clinically unaffected father. A third affected child did not carry the deletion. Similarly, inherited and de novo intragenic duplications disrupting CNTN4 in individuals with an ASD have also recently been reported [Glessner et al., 2009; Roohi et al., 2009]. We recently identified a maternally inherited deletion of 3p26.3 that includes the 5′ UTR of CNTN4 in a child with severe autism. Based on the increasing evidence implicating contactins in ASDs, as well as localization of CNTN4 within the 3p− syndrome critical region, we undertook sequencing of the coding regions of the gene in a local cohort of ASD patients.

Cardiovascular disease is a leading cause of mortality worldwide. While the etiology for the majority of cardiovascular disease is presumed to be a combination of genetic and environmental factors, developments in understanding the basic biology of cardiac disorders have been greatly advanced through discoveries made studying heart diseases that exhibit Mendelian forms of inheritance. Most of these diseases primarily affect children and young adults and include cardiomyopathies, arrhythmias, aortic aneurysms, and congenital heart defects. The discovery of the genetic etiologies for these diseases have had significant impact on our understanding of more complex forms of cardiovascular disease and in some cases have led to novel diagnostic and treatment modalities. In this review, we will summarize these seminal genetic discoveries, highlighting a few that have resulted in significant impact on human disease, and discuss the potential utility of studying Mendelian-inherited heart disease with the development of new genetic technologies and our increased understanding of the human genome.

There is a strong genetic component to autism spectrum disorders (ASD), but due to significant genetic heterogeneity, individual genetic abnormalities contribute a small percentage to the overall total. Previous studies have demonstrated PTEN mutations in a sizable proportion of individuals with ASD or mental retardation/developmental delays (MR/DD) and macrocephaly that do not have features of Cowden or Bannayan-Riley-Ruvalcaba syndrome. This study was performed to confirm our previous results. We reviewed the charts of individuals who had PTEN clinical sequencing performed at our institution from January 2008 to July 2009. There were 93 subjects tested from our institution during that period. PTEN mutations were found in 2/39 (5.1%) ASD patients and 2/51 (3.9%) MR/DD patients. Three additional patients without mutations had no diagnostic information. Multiple relatives of individuals with a PTEN mutation had macrocephaly, MR, or early onset cancer (breast, renal, and prostate). Of those relatives tested, all had the familial PTEN mutation. None of the affected relatives had previously been diagnosed with Cowden or Bannayan-Riley-Ruvalcaba syndrome. We noted in our previous study several adult relatives without any findings who carried a mutation. Combined with data from our previous cohort, we have found PTEN mutations in 7/99 (7.1%) of individuals with ASD and 8/100 (8.0%) of individuals with MR/DD, all of whom had macrocephaly. We recommend testing for mutations in PTEN for individuals with ASD or MR/DD and macrocephaly. If mutations are found, other family members should be offered testing and the adults offered cancer screening if they have a PTEN mutation.

Segmental duplications, which comprise approximately 5%-10% of the human genome, are known to mediate medically relevant deletions, duplications, and inversions through nonallelic homologous recombination (NAHR) and have been suggested to be hot spots in chromosome evolution and human genomic instability. We report seven individuals with microdeletions at 17q23.1q23.2, identified by microarray-based comparative genomic hybridization (aCGH). Six of the seven deletions are approximately 2.2 Mb in size and flanked by large segmental duplications of98% sequence identity and in the same orientation. One of the deletions is approximately 2.8 Mb in size and is flanked on the distal side by a segmental duplication, whereas the proximal breakpoint falls between segmental duplications. These characteristics suggest that NAHR mediated six out of seven of these rearrangements. These individuals have common features, including mild to moderate developmental delay (particularly speech delay), microcephaly, postnatal growth retardation, heart defects, and hand, foot, and limb abnormalities. Although all individuals had at least mild dysmorphic facial features, there was no characteristic constellation of features that would elicit clinical suspicion of a specific disorder. The identification of common clinical features suggests that microdeletions at 17q23.1q23.2 constitute a novel syndrome. Furthermore, the inclusion in the minimal deletion region of TBX2 and TBX4, transcription factors belonging to a family of genes implicated in a variety of developmental pathways including those of heart and limb, suggests that these genes may play an important role in the phenotype of this emerging syndrome.

Two sisters (ages 16 yr and 15 yr) have been followed by our clinical genetics team for several years. Both girls have severe intellectual disability, hypotonia, seizures, and distinctive craniofacial features. The parents are healthy and have no other children. Oligo array, fragile X testing, and numerous single-gene tests were negative. All four family members underwent research exome sequencing, which revealed a heterozygous nonsense mutation in ASXL3 (p.R1036X) that segregated with disease. Exome data and independent Sanger sequencing confirmed that the variant is de novo, suggesting possible germline mosaicism in one parent. The p.R1036X variant has never been observed in healthy human populations and has been previously reported as a pathogenic mutation. Truncating de novo mutations in ASXL3 cause Bainbridge–Ropers syndrome (BRPS), a developmental disorder with similarities to Bohring–Opitz syndrome. Fewer than 30 BRPS patients have been described in the literature; to our knowledge, this is the first report of the disorder in two related individuals. Our findings lend further support to intellectual disability, absent speech, autistic traits, hypotonia, and distinctive facial appearance as common emerging features of Bainbridge–Ropers syndrome.

Hypertrophic cardiomyopathy (HCM) is a common autosomal dominant condition with an increased risk of sudden cardiac death. Although clinical genetic testing can be used for confirmation of a clinical diagnosis as well as a predictive test, based on our clinical experience it is underutilized. Therefore, we developed and administered a questionnaire to assess potential determinants of parental interest in this testing. Of the 30 adult caregivers who participated, 80% had heard of genetic testing, whereas only 30% knew about genetic testing specifically for HCM. Once informed of the availability, 62% said they would consider testing in the future and 28% would consider it in the next year. Participants' younger age, higher education level, knowledge of carrier testing, and positive view of genetic testing were significantly associated with the participant considering HCM genetic testing for their child (por= 0.05). Based on a logistic regression model, age, education level, and knowing that HCM is an inherited disease were the best predictors of who would consider genetic testing. This study provides healthcare providers with a framework to understand caregivers' knowledge and views of genetic testing, which can be used to improve clinical care for pediatric HCM patients.

Mutations in the gene encoding the cholesterol biosynthetic enzyme NSDHL are associated with the X-linked male-lethal bare patches (Bpa) mouse. Mutant male embryos for several Nsdhl alleles die in midgestation with placental insufficiency. We examined here a possible role of the maternal genotype in such placental pathology. Pre-pregnancy plasma cholesterol levels were similar between wild-type (WT) and Bpa(1H)/+ dams fed a standard, cholesterol-free diet. However, there was a marked decrease in cholesterol levels between embryonic day (E)8.5 and E10.5 for both genotypes. Further, there was a significant lag between E11.5 and E13.5 (P = 0.0011) in the recovery of levels in Bpa(1H)/+ dams to their pre-pregnancy values. To investigate possible effects of the maternal genotype on fetal placentation, we generated transgenic mice that expressed human NSDHL and rescued the male lethality of the Bpa(1H) null allele. We then compared placenta area at E10.5 in WT and Bpa(1H)/+ female embryos where the mutant X chromosome was transmitted from a heterozygous mother or a rescued mutant father. In mutant conceptuses, placental areas were approximately 50% less than WT. Surprisingly, expression of Nsdhl in trophoblast lineages of the placenta and yolk sac endoderm, which occurs only from the maternally inherited allele in a female embryo, had the largest effect on placental area (-0.681 mm(2); P < 0.0001). The maternal genotype had a smaller effect, independent of the fetal genotype (-0.283 mm(2); P = 0.024). These data demonstrate significant effects of the mother and fetal membranes on pregnancy outcome, with possible implications for cholesterol homeostasis during human pregnancy.

The left ventricular outflow tract (LVOT) malformations aortic valve stenosis (AVS), coarctation of the aorta (CoA), and hypoplastic left heart syndrome (HLHS) are significant causes of infant mortality. These three malformations are thought to share developmental pathogenetic mechanisms. A strong genetic component has been demonstrated earlier, but the underlying genetic etiologies are unknown. Our objective was to identify genetic susceptibility loci for the broad phenotype of LVOT malformations. We genotyped 411 microsatellites spaced at an average of 10 cM in 43 families constituting 289 individuals, with an additional 5 cM spaced markers for fine mapping. A non-parametric linkage (NPL) analysis of the combined LVOT malformations gave three suggestive linkage peaks on chromosomes 16p12 (NPL score (NPLS)=2.52), 2p23 (NPLS=2.41), and 10q21 (NPLS=2.14). Individually, suggestive peaks for AVS families occurred on chromosomes 16p12 (NPLS=2.64), 7q36 (NPLS=2.31), and 2p25 (NPLS=2.14); and for CoA families on chromosome 1q24 (NPLS=2.61), 6p23 (NPLS=2.29), 7p14 (NPLS=2.27), 10q11 (NPLS=1.98), and 2p15 (NPLS=2.02). Significant NPLS in HLHS families were noted for chromosome 2p15 (NPLS=3.23), with additional suggestive peaks on 19q13 (NPLS=2.16) and 10q21 (NPLS=2.07). Overlapping linkage signals on 10q11 (AVS and CoA) and 16p12 (AVS, CoA, and HLHS) led to higher NPL scores when all malformations were analyzed together. In conclusion, we report suggestive evidence for linkage to chromosomes 2p23, 10q21, and 16p12 for the LVOT malformations of AVS, CoA, and HLHS individually and in a combined analysis, with a significant peak on 2p15 for HLHS. Overlapping linkage peaks provide evidence for a common genetic etiology.

Renal agenesis/adysplasia is the leading etiology of end stage renal disease in children. The etiology for renal agenesis/adysplasia has not been identified. The purpose of the present study was to determine if renal agenesis/adysplasia occur in a familial pattern. Twenty seven cases of bilateral renal agenesis/adysplasia were identified by review of autopsy records, and four were excluded. A male excess of 2.8:1 was noted with a mean gestation of 35 weeks. Prenatal and family histories were obtained on 11/23 families. Potential embryologic stressors were identified in 8/11 pregnancies. Thirty-four 1st and 2nd degree relatives from five families participated in a renal ultrasound exam. An increased prevalence of congenital renal anomalies was identified in the relatives of index patients with bilateral renal agenesis/adysplasia (14.7%) compared to controls (2.2%), with a recurrence risk of 6.2 for 1st degree relatives. The most frequently identified renal anomalies in the family members were solitary kidneys and duplicated collecting systems. The increased prevalence of a range of renal anomalies within affected families raises the possibility that isolated renal malformations result from unidentified gene-environment interactions.

Mucopolysaccharidosis type II (Hunter syndrome) is a lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase leading to tissue accumulation of glycosaminoglycans. It manifests with short stature, joint stiffness, coarse facial features, hepatosplenomegaly, and progressive mental retardation. Most children die in the first or second decade from pulmonary or cardiac involvement. Until recently, no specific treatment was available. A Phase II/III trial of idursulfase, a recombinant enzyme replacement therapy for this disorder, demonstrated significant improvement in a 6-min walk test and in pulmonary function tests, and a decrease in liver and spleen size among those receiving active therapy once weekly. Major side effects include allergic reactions, which generally are easily managed and do not require discontinuing therapy. Idursulfase is now approved in the US, and should provide significant improvement in quality of life for these individuals. This article reviews the disease and treatment, with comments on future therapeutic directions.

Basic knowledge of genetics is essential for understanding genetic testing and counseling. The lack of a written, English language, validated, published measure has limited our ability to evaluate genetic knowledge of patients and families. Here, we begin the psychometric analysis of a true/false genetic knowledge measure. The 18-item measure was completed by parents of children with congenital heart defects (CHD) (n = 465) and adolescents and young adults with CHD (age: 15-25, n = 196) with a mean total correct score of 12.6 [standard deviation (SD) = 3.5, range: 0-18]. Utilizing exploratory factor analysis, we determined that one to three correlated factors, or abilities, were captured by our measure. Through confirmatory factor analysis, we determined that the two factor model was the best fit. Although it was necessary to remove two items, the remaining items exhibited adequate psychometric properties in a multidimensional item response theory analysis. Scores for each factor were computed, and a sum-score conversion table was derived. We conclude that this genetic knowledge measure discriminates best at low knowledge levels and is therefore well suited to determine a minimum adequate amount of genetic knowledge. However, further reliability testing and validation in diverse research and clinical settings is needed.