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The phenotypic repercussion of ZDHHC15 haploinsufficiency is not well-known. This gene was initially suggested as a candidate for X-linked mental retardation, but such an association was later questioned. We studied a multiplex family with three members with autism spectrum disorder (ASD) by array CGH, karyotype, exome sequencing and X-chromosome inactivation patterns. Medical history interviews, cognitive and physical examinations, and sensory profiling were also assessed. The three family members with ASD (with normal cognitive abilities and an abnormal sensory profile) were the only carriers of a 1.7 Mb deletion in the long arm of chromosome X, involving: ZDHHC15, MAGEE2, PBDC1, MAGEE1, MIR384 and MIR325. The normal chromosome X was preferentially inactivated in female carriers, and the whole exome sequencing of an affected family member did not reveal any additional genetic variant that could explain the phenotype. Thus, in the present family, ASD segregates with a deletion on chromosome X that includes ZDHHC15. Considering our results together with gene data (regarding function, expression, conservation and animal/cellular models), ZDHHC15 is a candidate gene for ASD. Emerging evidence also suggests that this gene could be associated with other neurodevelopmental disorders, with incomplete penetrance and variable expressivity.

GLYT1 encephalopathy is a form of glycine encephalopathy caused by disturbance of glycine transport. The phenotypic spectrum of the disease has not yet been completely described, as only four unrelated families with the disorder have been reported to date. Common features of affected patients include neonatal hypotonia, respiratory failure, encephalopathy, myoclonic jerks, dysmorphic features, and musculoeskeletal anomalies. All reported affected patients harbor biallelic genetic variants in SLC6A9. SNP array together with Sanger sequencing were performed in a newborn with arthrogryposis and severe neurological impairment. The novel genetic variant c.997delC in SLC6A9 was detected in homozygous state in the patient. At protein level, the predicted change is p.(Arg333Alafs*3), which most probably results in a loss of protein function. The variant cosegregated with the disease in the family. A subsequent pregnancy with ultrasound anomalies was also affected. The proband presented the core phenotypic features of GLYT1 encephalopathy, but also a burst suppression pattern on the electroencephalogram, a clinical feature not previously associated with the disorder. Our results suggest that the appearance of this pattern correlates with higher cerebrospinal fluid glycine levels and cerebrospinal fluid/plasma glycine ratios. A detailed discussion on the possible pathophysiological mechanisms of the disorder is also provided.

Sudden infant death syndrome is the leading cause of death during the first year of life. A large part of cases remains without a conclusive cause of death after complete autopsy. In these situations, cardiac arrhythmia of genetic origin is suspected as the most plausible cause of death. Our aim was to ascertain whether genetic variants associated with sudden cardiac death might be the cause of death in a cohort of infants died suddenly. We analyzed 108 genes associated with sudden cardiac death in 44 post-mortem samples of infants less than 1 year old of age who died at rest. Definite cause of death was not conclusive in any case after a complete autopsy. Genetic analysis identified at least one rare variant in 90.90% of samples. A total of 121 rare genetic variants were identified. Of them, 33.05% were novel and 39.66% were located in genes encoding ion channels or associated proteins. A comprehensive genetic analysis in infants who died suddenly enables the unraveling of potentially causative cardiac variants in 2045% of cases. Molecular autopsy should be included in forensic protocols when no conclusive cause of death is identified. Large part genetic variants remain of uncertain significance, reinforcing the crucial role of genetic interpretation before clinical translation but also in early identification of relatives at risk.

In order to contribute to the knowledge of type and frequency of chromosome abnormalities in early pregnancy losses, we analyzed the cytogenetic results from a large series of first trimester miscarriages, using a diagnostic approach with a high success rate and no maternal contamination. A total of 1,119 consecutive chorionic villi samples were obtained before evacuation, and karyotypes were prepared after short-term culture (STC). In 603 samples, a long-term culture (LTC) was also performed. The overall and individual frequencies of the different types of chromosome abnormalities were established, including placental mosaicisms, and their relationship with maternal age and gestational weeks was assessed. An abnormal karyotype was detected in 70.3% of the samples. Single autosomal trisomy was the most frequent abnormality (64.6% of the abnormal cases), followed by triploidy (13.1%) and monosomy X (10.4%). Chromosome rearrangements were found in 5.2%, combined abnormalities in 8.9%, and placental mosaicism in 3.5% of the cases with STC and LTC performed. Individual trisomies behaved differently with respect to maternal age and intrauterine survival. Due to the combination of STC and LTC, our study offers reliable information on the incidence and type of chromosome abnormalities and placental mosaicism in miscarriages and contributes to define the cytogenetic implication in their etiology., This work was partially supported by grants PI11/01841 (IP: A. Sánchez) and PI14/00588 (IP: A. Borrell) from Instituto de Salud Carlos III (Spain) and jointly financed by Fondo Europeo de Desarrollo Regional, Union Europea, Una manera de hacer Europa (FEDER).

Over the last ten years, analysis of copy number variants has increasingly been applied to the study of arrhythmogenic pathologies associated with sudden death, mainly due to significant advances in the field of massive genetic sequencing. Nevertheless, few published reports have focused on the prevalence of copy number variants associated with sudden cardiac death. As a result, the frequency of these genetic alterations in arrhythmogenic diseases as well as their genetic interpretation and clinical translation has not been established. This review summarizes the current available data concerning copy number variants in sudden cardiac death-related diseases.

The name of author M. Alejandra Restrepo-Cordoba was parsed incorrectly (in such a way as to suggest that her surname is "Alejandra Restrepo-Cordoba") in this article as published.

Several studies have identified copy number variants (CNVs) as responsible for cardiac diseases associated with sudden cardiac death (SCD), but very few exhaustive analyses in large cohorts of patients have been performed, and they have been generally focused on a specific SCD-related disease. The aim of the present study was to screen for CNVs the most prevalent genes associated with SCD in a large cohort of patients who suffered sudden unexplained death or had an inherited cardiac disease (cardiomyopathy or channelopathy). A total of 1765 European patients were analyzed with a homemade algorithm for the assessment of CNVs using high-throughput sequencing data. Thirty-six CNVs were identified (2%), and most of them appeared to have a pathogenic role. The frequency of CNVs among cases of sudden unexplained death, patients with a cardiomyopathy or a channelopathy was 1.4% (8/587), 2.3% (20/874), and 2.6% (8/304), respectively. Detection rates were particularly high for arrhythmogenic cardiomyopathy (5.1%), long QT syndrome (4.7%), and dilated cardiomyopathy (4.4%). As such large genomic rearrangements underlie a non-neglectable portion of cases, we consider that their analysis should be performed as part of the routine genetic testing of sudden unexpected death cases and patients with SCD-related diseases. post-print 1349 KB

Sudden cardiac death is a natural and unexpected death that occurs within 1 h of the first symptom. Most sudden cardiac deaths occur during exercise, mostly as a result of myocardial infarction. After autopsy, some cases, especially in the young, are diagnosed as cardiomyopathies or remain without a conclusive cause of death. In both situations, genetic alterations may explain the arrhythmia. Our aim was to identify a genetic predisposition to sudden cardiac death in a cohort of post-mortem cases of individuals who died during exercise, with a structurally normal heart, and were classified as arrhythmogenic death. We analyzed a cohort of 52 post-mortem samples from individuals

Introduction Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited heart disease. Next-generation sequencing (NGS) is the preferred genetic test, but the diagnostic value of screening for minor and candidate genes, and the role of copy number variants (CNVs) deserves further evaluation. Methods Three hundred and eighty-seven consecutive unrelated patients with HCM were screened for genetic variants in the 5 most frequent genes (MYBPC3, MYH7, TNNT2, TNNI3 and TPM1) using Sanger sequencing (N = 84) or NGS (N = 303). In the NGS cohort we analyzed 20 additional minor or candidate genes, and applied a proprietary bioinformatics algorithm for detecting CNVs. Additionally, the rate and classification of TTN variants in HCM were compared with 427 patients without structural heart disease. Results The percentage of patients with pathogenic/likely pathogenic (P/LP) variants in the main genes was 33.3%, without significant differences between the Sanger sequencing and NGS cohorts. The screening for 20 additional genes revealed LP variants in ACTC1, MYL2, MYL3, TNNC1, GLA and PRKAG2 in 12 patients. This approach resulted in more inconclusive tests (36.0% vs. 9.6%, p

The heritable cardiovascular disorder long QT syndrome (LQTS), characterized by prolongation of the QT interval on electrocardiogram, carries a high risk of sudden cardiac death. We sought to add new data to the existing knowledge of genetic mutations contributing to LQTS to both expand our understanding of its genetic basis and assess the value of genetic testing in clinical decision-making. Direct sequencing of the five major contributing genes, KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2, was performed in a cohort of 115 non-related LQTS patients. Pathogenicity of the variants was analyzed using family segregation, allele frequency from public databases, conservation analysis, and Condel and Provean in silico predictors. Phenotype-genotype correlations were analyzed statistically. Sequencing identified 36 previously described and 18 novel mutations. In 51.3% of the index cases, mutations were found, mostly in KCNQ1, KCNH2, and SCN5A; 5.2% of cases had multiple mutations. Pathogenicity analysis revealed 39 mutations as likely pathogenic, 12 as VUS, and 3 as non-pathogenic. Clinical analysis revealed that 75.6% of patients with QTc≥500 ms were genetically confirmed. Our results support the use of genetic testing of KCNQ1, KCNH2, and SCN5A as part of the diagnosis of LQTS and to help identify relatives at risk of SCD. Further, the genetic tools appear more valuable as disease severity increases. However, the identification of genetic variations in the clinical investigation of single patients using bioinformatic tools can produce erroneous conclusions regarding pathogenicity. Therefore segregation studies are key to determining causality.

Objectives To assess the frequency of karyotype abnormalities and chromosome 22q11.2 deletion syndrome among fetuses with abnormal cardiac ultrasound findings, and to evaluate the clinical value of chromosomal microarray-based analysis (CMA) in the study of such pregnancies. Methods First, we carried out retrospective analysis of karyotype abnormalities and 22q11.2 deletion syndrome cases diagnosed between January 2009 and December 2011 in our center among fetuses with abnormal cardiac ultrasound findings (n = 276). Second, CMA was performed in 51 of the fetuses with such findings, normal karyotype and negative or no 22q11.2 deletion syndrome study, and in the only fetus with a heart defect and an apparently balanced de novo chromosomal rearrangement. Results Out of the 276 pregnancies with abnormal cardiac ultrasound findings, karyotyping revealed a chromosomal abnormality in 44 (15.9%). Of fetuses with normal karyotype in which 22q11.2 deletion syndrome studies were performed, 6.4% (5/78) had this microdeletion syndrome. Among fetuses with abnormal cardiac findings, normal karyotype and negative or no 22q11.2 deletion syndrome study that underwent CMA, the detection rate of pathogenic copy number variants not detected by conventional cytogenetics was 2.0% (1/51), and no variants of uncertain clinical significance were found. In the fetus with a heart defect and an apparently balanced de novo chromosomal rearrangement, CMA revealed that the rearrangement was not truly balanced. Conclusions In the assessment of genetic abnormalities in pregnancies with abnormal cardiac ultrasound findings, the diagnostic yield may be increased by 2% if CMA is used as a complementary tool to conventional cytogenetics. Our results suggest that CMA could be a good alternative to karyotyping in these pregnancies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Aims: This study sought to determine the usefulness of genetic testing to predict evolution in hypertrophic cardiomyopathy (HCM) and to assess the role of genetic testing in clinical practice. Methods and Results: Genetic results of 100 HCM patients tested for mutations in ≥10 HCM-causing genes were evaluated. Patients were classified as with poor (Group A) or favourable(Group B) clinical course. Forty-five pathogenic mutations (PM) were identified in 28 patients (56%) from Group A and in 23 (46%) from Group B (p=0.317). Only 40 patients (40%) exhibited PM that had been previously reported and only 15 (15%) had PM reported in ≥10 individuals. PM associated with poor prognosis were identified in just 5 patients from Group A (10%). Conclusion: Genetic findings are not useful to predict prognosis in most HCM patients. By contrast, real-world data reinforce the usefulness of genetic testing to provide genetic counselling and to enable cascade genetic screening. pre-print 298 KB

Sudden cardiac arrest is a leading cause of death worldwide. Most cardiac arrests happen in patients who have previously suffered a myocardial infarct. The risk of sudden death after infarction may increase in people who carry a pathogenic genetic alteration in cardiac ion channels. We hypothesized that micro-ischemia could trigger lethal arrhythmogenesis, thus we sought to identify genetic alterations in cardiac ion channels in patients with micro-ischemic disease. We studied a cohort of 56 post-mortem samples. Autopsy studies identified myocardial infarction as the cause of death in each case. We used both Sanger sequencing and next-generation sequencing to screen candidate genes associated with sudden cardiac death. We identified six rare missense genetic variations in five unrelated patients. Two variants have been previously reported; one is associated with atrial fibrillation (SCN5A_p.H445D), and the other is predicted to be benign (ANK2_p.T2059M). The novel variants were predicted in silico as benign, except for one (RyR2_p.M4019T), which was classified as deleterious. Our post-mortem, micro-infarction cohort displayed a rate of nearly 10% non-common genetic variants. However, the clinical significance of most of the identified variants remains unknown due to lack of family assessment. Further analyses should be performed in large cohorts to clarify the role of ion-channel gene analysis in samples showing microscopic ischemic alterations.

4q21 microdeletion syndrome (MIM: 613509) is a new genomic disorder characterized by intellectual disability, absent or severely delayed speech, growth retardation, hypotonia, variable brain malformation, and facial dysmorphism. The critical genes had been proposed based on an overlapping 1.37 Mb genomic region. No further refinement has been done since year 2010. Here, we present three cases with 4q21 deletion identified by clinical chromosomal microarray analysis. One of the cases have a de novo 761 kb deletion which is the smallest deletion ever reported at this locus. It provides an opportunity to further define the critical regions/genes associated with specific features of the 4q21 microdeletion syndrome. The evidence support the notion that PRKG2 and RASGEF1B are critical genes for intellectual disability and speech defect, and the heterogeneous nuclear ribonucleoprotein HNRNPD and HNRNPDL (previously known as HNRPDL) genes are associated with growth retardation and hypotonia. © 2016 Wiley Periodicals, Inc.

PURPOSE: Brugada syndrome (BrS) is a form of cardiac arrhythmia which may lead to sudden cardiac death. The recommended genetic testing (direct sequencing of SCN5A) uncovers disease-causing SNVs and/or indels in ~20% of cases. Limited information exists about the frequency of copy number variants (CNVs) in SCN5A in BrS patients, and the role of CNVs in BrS-minor genes is a completely unexplored field. METHODS: 220 BrS patients with negative genetic results were studied to detect CNVs in SCN5A. 63 cases were also screened for CNVs in BrS-minor genes. Studies were performed by Multiplex ligation-dependent probe amplification or Next-Generation Sequencing (NGS). RESULTS: The detection rate for CNVs in SCN5A was 0.45% (1/220). The detected imbalance consisted of a duplication from exon 15 to exon 28, and could potentially explain the BrS phenotype. No CNVs were found in BrS-minor genes. CONCLUSION: CNVs in current BrS-related genes are uncommon among BrS patients. However, as these rearrangements may underlie a portion of cases and they undergo unnoticed by traditional sequencing, an appealing alternative to conventional studies in these patients could be targeted NGS, including in a single experiment the study of SNVs, indels and CNVs in all the known BrS-related genes

Objective To evaluate the usefulness of subtelomeric multiplex ligation-dependent probe amplification (MLPA) in both the detection of subtelomeric rearrangements in fetuses with ultrasound abnormalities and normal karyotype, and the characterization of cytogenetically detectable rearrangements. Method We studied by subtelomeric MLPA 229 pregnancies with ultrasound findings and normal karyotype (Group 1) and five pregnancies with a cytogenetically visible but not microscopically characterizable rearrangement (Group 2). The detected imbalances were confirmed by fluorescence in situ hybridization (FISH) and parents were also studied. Results In Group 1, two clinically relevant subtelomeric imbalances (14qter deletion and 20pter deletion) and one subtelomeric imbalance of uncertain significance (X/Ypter duplication) were diagnosed, showing a detection rate of cryptic subtelomeric imbalances in these pregnancies of 1.3%. However, only 14qter deletion seems to be clearly associated with the observed prenatal findings. In Group 2, MLPA contributed to the precise description of the chromosome abnormalities. Conclusion The low detection rate of subtelomeric imbalances and the poor genotype–phenotype correlations in pregnancies with ultrasound abnormalities and normal karyotype suggest that subtelomeric MLPA is not a crucial tool in the prenatal diagnosis of these cases. However, our work provides evidence that MLPA is very useful for the characterization of unbalanced karyotypes. Copyright © 2010 John Wiley & Sons, Ltd.

We report on a girl with mild dysmorphic facial features, Dandy–Walker malformation (DWM), iris coloboma, profound hearing loss, and hyperlaxity of skin and joints, whose karyotype is 46,XX,t(6;13)(q23;q32)dn and who has a cryptic imbalance at the 13q32 translocation breakpoint assessed by array-CGH. Our patient has many clinical manifestations in common with those of the previously reported cases of 13q32 deletions, which suggests that at least part of the abnormal phenotype is probably due to the imbalance. The recurrent finding of DWM among patients with 13q deletions has led to the suggestions that candidate gene/s for its development are on chromosome 13. We describe the smallest 13q deletion associated to DWM, which allows further narrowing of the previously established critical region for this brain malformation to 13q32.2-32.3. Among the few genes of the deleted region, ZIC2 and ZIC5 seem the most plausible candidates, which is in keeping with some previous reports. This work also illustrates the usefulness of array-CGH platforms in the identification of cryptic imbalances in carriers of apparently balanced rearrangements with abnormal phenotypes. © 2010 Wiley-Liss, Inc.

Interstitial deletions of the short arm of chromosome 3 are rare, and a specific clinical phenotype has not been defined. We report the first isolated cryptic proximal interstitial 3p deletion, del(3)(p12.3p13), assessed by array-based comparative genomic hybridization in a girl with an inversion of chromosome 7, whose phenotype includes neurodevelopmental delay, growth retardation, dysmorphic facial features, hypophysis hypoplasia, gastroesophageal reflux, clinodactyly, preauricular appendix, and myopia. Her features are similar to those observed in the previously reported cases of proximal 3p deletions overlapping with our imbalance, indicating that her clinical manifestations are likely to be due to the deletion. As our patient’s imbalance is the first non-cytogenetically visible proximal interstitial 3p deletion uncomplicated by other imbalances, its characterization has allowed us to narrow the minimal deletion interval associated with growth retardation and neurodevelopmental delay to the 3p12.3–p13 region. Among the genes found in this region, ROBO1, ROBO2, PDZRN3 and CNTN3 might play a role in the neurodevelopmental delay of the patient. This study provides additional evidence that cryptic imbalances anywhere along the genome can be found in patients with phenotypic abnormalities and a balanced chromosome rearrangement.

A leading cause of death in western countries is sudden cardiac death, and can be associated with genetic disease. Next-generation sequencing has allowed thorough analysis of genes associated with this entity, including, most recently, titin. We aimed to identify potentially pathogenic genetic variants in titin. A total of 1126 samples were analyzed using a custom sequencing panel including major genes related to sudden cardiac death. Our cohort was divided into three groups: 432 cases from patients with cardiomyopathies, 130 cases from patients with channelopathies, and 564 post-mortem samples from individuals showing anatomical healthy hearts and non-conclusive causes of death after comprehensive autopsy. None of the patients included had definite pathogenic variants in the genes analyzed by our custom cardio-panel. Retrospective analysis comparing the in-house database and available public databases also was performed. We identified 554 rare variants in titin, 282 of which were novel. Seven were previously reported as pathogenic. Of these 554 variants, 493 were missense variants, 233 of which were novel. Of all variants identified, 399 were unique and 155 were identified at least twice. No definite pathogenic variants were identified in any of genes analyzed. We identified rare, mostly novel, titin variants that seem to play a potentially pathogenic role in sudden cardiac death. Additional studies should be performed to clarify the role of these variants in sudden cardiac death.

BACKGROUND: Brugada syndrome (BrS) is a rare genetic cardiac arrhythmia that can lead to sudden cardiac death in patients with a structurally normal heart. Genetic variations in SCN5A can be identified in approximately 20-25% of BrS cases. The aim of our work was to determine the spectrum and prevalence of genetic variations in a Spanish cohort diagnosed with BrS. METHODOLOGY/PRINCIPAL FINDINGS: We directly sequenced fourteen genes reported to be associated with BrS in 55 unrelated patients clinically diagnosed. Our genetic screening allowed the identification of 61 genetic variants. Of them, 20 potentially pathogenic variations were found in 18 of the 55 patients (32.7% of the patients, 83.3% males). Nineteen of them were located in SCN5A, and had either been previously reported as pathogenic variations or had a potentially pathogenic effect. Regarding the sequencing of the minority genes, we discovered a potentially pathogenic variation in SCN2B that was described to alter sodium current, and one nonsense variant of unknown significance in RANGRF. In addition, we also identified 40 single nucleotide variations which were either synonymous variants (four of them had not been reported yet) or common genetic variants. We next performed MLPA analysis of SCN5A for the 37 patients without an identified genetic variation, and no major rearrangements were detected. Additionally, we show that being at the 30-50 years range or exhibiting symptoms are factors for an increased potentially pathogenic variation discovery yield./nCONCLUSIONS: In summary, the present study is the first comprehensive genetic evaluation of 14 BrS-susceptibility genes and MLPA of SCN5A in a Spanish BrS cohort. The mean pathogenic variation discovery yield is higher than that described for other European BrS cohorts (32.7% vs 20-25%, respectively), and is even higher for patients in the 30-50 years age range. This work was supported by Obra social “la Caixa” (www.obrasocial.lacaixa.es/), Centro Nacional de Investigaciones Cardiovasculares (CNIC-03-2008; www.cnic.es/), and Instituto de Salud Carlos III (FISPI08/1800 and Fondo Europeo de Desarrollo Regional; www.isciii.es/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Background Long QT Syndrome is an inherited channelopathy leading to sudden cardiac death due to ventricular arrhythmias. Despite that several genes have been associated with the disease, nearly 20% of cases remain without an identified genetic cause. Other genetic alterations such as copy number variations have been recently related to Long QT Syndrome. Our aim was to take advantage of current genetic technologies in a family affected by Long QT Syndrome in order to identify the cause of the disease. Methods Complete clinical evaluation was performed in all family members. In the index case, a Next Generation Sequencing custom-built panel, including 55 sudden cardiac death-related genes, was used both for detection of sequence and copy number variants. Next Generation Sequencing variants were confirmed by Sanger method. Copy number variations variants were confirmed by Multiplex Ligation dependent Probe Amplification method and at the mRNA level. Confirmed variants and copy number variations identified in the index case were also analyzed in relatives. Results In the index case, Next Generation Sequencing revealed a novel variant in TTN and a large deletion in KCNQ1, involving exons 7 and 8. Both variants were confirmed by alternative techniques. The mother and the brother of the index case were also affected by Long QT Syndrome, and family cosegregation was observed for the KCNQ1 deletion, but not for the TTN variant. Conclusions Next Generation Sequencing technology allows a comprehensive genetic analysis of arrhythmogenic diseases. We report a copy number variation identified using Next Generation Sequencing analysis in Long QT Syndrome. Clinical and familiar correlation is crucial to elucidate the role of genetic variants identified to distinguish the pathogenic ones from genetic noise.

Congenital heart defects (CHD) represent the most common birth defects, so they are not a rare finding when performing routine ultrasound examinations during pregnancy. Once chromosome abnormalities have been excluded in a fetus with a CHD, chromosome 22q11.2 deletion is usually investigated by FISH, as it is the most frequent microdeletion syndrome and is generally associated with cardiac malformations. If 22q11.2 microdeletion is ruled out, the etiology of the CHD remains generally unexplained, making familial genetic counseling difficult. To evaluate the usefulness of Multiplex Ligation-dependent Probe Amplification (MLPA) kits designed for the study of 22q11.2 and other genomic regions previously associated with syndromic CHD, we performed MLPA in 55 pregnancies with fetuses presenting CHD, normal karyotype and negative FISH results for 22q11.2 microdeletion, which constitutes the largest prenatal series reported. Definitive MLPA results were obtained in 50 pregnancies, and in this setting such MLPA kits did not detect any imbalance. On the other hand, to compare FISH and MLPA techniques for the study of 22q11.2 microdeletions, we performed MLPA in 4 pregnancies known to have 22q11.2 deletions (by FISH). All four 22q11.2 microdeletions were also detected by MLPA, which corroborates that it is a reliable technique for the diagnosis and characterization of 22q11.2 deletions. Finally, we evaluated the possibility of replacing conventional FISH by MLPA for the prenatal diagnosis of CHD, comparing the diagnostic potential, results delivery times, repetition and failure rates and cost of both techniques, and concluded that FISH should still be the technique of choice for the prenatal diagnosis of fetuses with CHD.

Chromosome abnormalities are one of the main causes of congenital defects, and establishing their frequency according to the different clinical indications for invasive procedure during pregnancy is especially important for genetic counselling. We analyzed the results of 29,883 amniotic fluid samples referred to our laboratory for cytogenetic studies from 1998 to 2009, which constitutes the largest series of cytogenetic analysis performed on amniotic fluid samples in Spain. The number of samples received tended to increase from 1998 to 2005, but after 2005 it decreased substantially. Cytogenetic results were obtained in 99.5% of the samples, and the detected incidence of chromosome abnormalities was 2.9%. Of these, 48.1% consisted of classical autosomal aneuploidies, trisomy 21 being the most frequent one. The main clinical indications for amniocentesis were positive prenatal screening and advanced maternal age, but referral reasons with highest positive predictive values were, excluding parental chromosome rearrangement, increased nuchal translucency (9.2%) and ultrasound abnormalities (6.6%). In conclusion, performing the karyotype on amniotic fluid samples is a good method for the detection of chromosome abnormalities during pregnancy. The number of cytogenetic studies on amniotic fluid has now decreased, however, due to the implementation of first trimester prenatal screening for the detection of Down syndrome, which allows karyotyping on chorionic villus samples. Our results also show that both ultrasound abnormalities and increased nuchal translucency are excellent clinical indicators for fetal chromosome abnormality.

To evaluate the usefulness of subtelomeric multiplex ligation-dependent probe amplification (MLPA) in both the detection of subtelomeric rearrangements in fetuses with ultrasound abnormalities and normal karyotype, and the characterization of cytogenetically detectable rearrangements.We studied by subtelomeric MLPA 229 pregnancies with ultrasound findings and normal karyotype (Group 1) and five pregnancies with a cytogenetically visible but not microscopically characterizable rearrangement (Group 2). The detected imbalances were confirmed by fluorescence in situ hybridization (FISH) and parents were also studied.In Group 1, two clinically relevant subtelomeric imbalances (14qter deletion and 20pter deletion) and one subtelomeric imbalance of uncertain significance (X/Ypter duplication) were diagnosed, showing a detection rate of cryptic subtelomeric imbalances in these pregnancies of 1.3%. However, only 14qter deletion seems to be clearly associated with the observed prenatal findings. In Group 2, MLPA contributed to the precise description of the chromosome abnormalities.The low detection rate of subtelomeric imbalances and the poor genotype-phenotype correlations in pregnancies with ultrasound abnormalities and normal karyotype suggest that subtelomeric MLPA is not a crucial tool in the prenatal diagnosis of these cases. However, our work provides evidence that MLPA is very useful for the characterization of unbalanced karyotypes. Copyright © 2010 John WileySons, Ltd.

Trisomy 20 mosaicism is a common abnormality found in prenatal diagnosis. Its clinical significance remains unclear since approximately 90-93% of cases result in normal phenotype. Only 5 cases of non-mosaic trisomy 20 in amniotic fluid culture surviving beyond the first trimester have been reported. Moreover, trisomic cells are generally not detectable in blood and have only been reported in three cases. We present a case of non-mosaic trisomy 20 found in chorionic villi sample and amniotic fluid culture in a fetus with minor abnormalities not detected by ultrasound examination. Pathological examination of the fetus only revealed right pulmonary isomerism and camptodactily, and no major malformations were disclosed. Trisomic lineage was also detected in fetal blood, kidney, skin and brain tissue cultures. Molecular analysis revealed that the extra chromosome 20 was originated in paternal meiosis. To our knowledge, we report the first prenatal case of non-mosaic trisomy 20 of paternal origin that has been confirmed in several fetal tissues, including blood, in a fetus with minor malformations not detected prenatally.

The identification of an unexpected structural chromosome rearrangement at prenatal diagnosis can be problematic and raises unique genetic counseling issues. We describe two consecutive prenatal cases within a family with an inherited unbalanced (Y;12) translocation and discuss the genotype-phenotype correlation. The first fetus presented with 12qter monosomy and pseudoautosomal region 2 trisomy, while the second fetus had the alternative unbalanced state. Although the first fetus had a structural heart defect, such small imbalances might not give sonographic findings, making their prenatal diagnosis difficult. However, congenital abnormalities are expected in both unbalanced forms of the translocation, including mental retardation, which could be explained by the gene dosage variation of P2RX2. To our knowledge, these are the first published cases reporting this subtype of (Y;12) translocation, in both balanced and unbalanced states.

Objective To describe the molecular and cytogenetic characterization of two different prenatal cases of androgenetic/biparental mosaicism and review the different possible mechanisms of origin in each case. Design Case study and literature review. Setting Tertiary medical center (prenatal diagnosis unit). Patient(s) A 26-year-old pregnant woman referred for suspected partial mole placenta and a 33-year-old pregnant woman referred for polyhydramnios and fetal malformations. Intervention(s) Ultrasound examination, prenatal invasive procedures, molecular and cytogenetic analysis, physical and pathologic evaluation, and genetic counseling. Main Outcome Measure(s) Cytogenetic analysis, fluorescent in situ hybridization, and quantitative fluorescence polymerase chain reaction (QF-PCR) analysis. Result(s) The finding of a normal karyotype together with a triploidy-like QF-PCR profile led to the diagnosis of two cases of androgenetic (genome-wide paternal uniparental disomy)/biparental mosaicism. The first case showed placental mesenchymal dysplasia and a normal fetus, and the second one presented a fetus showing Beckwith-Wiedemann syndrome features and an apparently normal placenta. Conclusion(s) These cases highlight the wide range of possible clinical presentations of androgenetic/biparental mosaicism, the variety of mechanisms of their origin, and the importance of the combination of molecular and cytogenetic analysis to achieve an accurate diagnosis and provide reproductive counseling.