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The increased utilization of clinical genomic sequencing in the past decade has ushered in the era of genomic medicine, requiring genetics providers to acquire new skills and adapt their practices. The change in workplace responsibilities of clinical/medical geneticists (CMGs) and genetic counselors (GCs) in North America, due to the evolution of genetic testing, has not been studied. We surveyed CMGs (n = 80) and GCs (n = 127) with experience in general/pediatric genetics to describe their current practice of clinical tasks and the change in regularity of performing these tasks over the past 5–10 years. Currently, complementarity of responsibilities between CMGs and GCs clearly exists but providers who have been in the field for longer have noted role changes. Trends indicate that fewer experienced CMGs perform physical exams and select genetic tests than before and fewer experienced GCs complete requisitions and write result letters. The frequency of CMGs and GCs who investigate genetic test results, however, has increased. This study provides insight into the changing landscape of clinical genetics practice. Our findings suggest that the roles and responsibilities of CMGs and GCs have shifted in the past decade. [ABSTRACT FROM AUTHOR]

Objective: Rare inherited missense variants in SLC32A1, the gene that encodes the vesicular gamma‐aminobutyric acid (GABA) transporter, have recently been shown to cause genetic epilepsy with febrile seizures plus. We aimed to clarify if de novo missense variants in SLC32A1 can also cause epilepsy with impaired neurodevelopment. Methods: Using exome sequencing, we identified four individuals with a developmental and epileptic encephalopathy and de novo missense variants in SLC32A1. To assess causality, we performed functional evaluation of the identified variants in a murine neuronal cell culture model. Results: The main phenotype comprises moderate‐to‐severe intellectual disability, infantile‐onset epilepsy within the first 18 months of life, and a choreiform, dystonic, or dyskinetic movement disorder. In silico modeling and functional analyses reveal that three of these variants, which are located in helices that line the putative GABA transport pathway, result in reduced quantal size, consistent with impaired filling of synaptic vesicles with GABA. The fourth variant, located in the vesicular gamma‐aminobutyric acid N‐terminus, does not affect quantal size, but increases presynaptic release probability, leading to more severe synaptic depression during high‐frequency stimulation. Thus, variants in vesicular gamma‐aminobutyric acid can impair GABAergic neurotransmission through at least two mechanisms, by affecting synaptic vesicle filling and by altering synaptic short‐term plasticity. Interpretation: This work establishes de novo missense variants in SLC32A1 as a novel cause of a developmental and epileptic encephalopathy. Summary for Social Media If Published: @platzer_k @lemke_johannes @RamiJamra @Nirgalito @GeneDxThe SLC family 32 Member 1 (SLC32A1) is the only protein identified to date, that loads gamma‐aminobutyric acid (GABA) and glycine into synaptic vesicles, and is therefore also known as the vesicular GABA transporter (VGAT) or vesicular inhibitory amino acid transporter (VIAAT). Rare inherited missense variants in SLC32A1, the gene that encodes VGAT/vesicular inhibitory amino acid transporter, have recently been shown to cause genetic epilepsy with febrile seizures plus.We aimed to clarify if de novo missense variants in SLC32A1 can also cause epilepsy with impaired neurodevelopment.We report on four individuals with de novo missense variants in SLC32A1 and a developmental and epileptic encephalopathy with infantile onset epilepsy. We establish causality of the variants via in silico modeling and their functional evaluation in a murine neuronal cell culture model.SLC32A1 variants represent a novel genetic etiology in neurodevelopmental disorders with epilepsy and a new GABA‐related disease mechanism. ANN NEUROL 2022;92:958–973 [ABSTRACT FROM AUTHOR]

Ehlers‐Danlos syndrome, hypermobility type (hEDS) is a heritable connective tissue disorder that currently does not have a known molecular etiology. Previous studies have explored the complex symptomology, clinical diagnosis, and psychological aspects of hEDS. Genetics providers currently aid in the diagnosis and management guidance of patients with hEDS, but there is limited data describing the needs and expectations of individuals with hEDS from a clinical genetics appointment. Our study sought to explore these items through the use of an online survey to assess participants' beliefs, needs and expectations (BNE) for genetic counseling as well as questions about demographics, hEDS symptoms, and current medical care. A total of 460 respondents with hEDS completed the survey. Most participants felt joint pain/weakness (n = 392; 88%) was one of the most disruptive symptoms of hEDS and 63% (n = 289) reported having psychiatric conditions. BNE scores were highest in two domains: expectations to have psychosocial concerns addressed during a genetic counseling appointment (mean score = 4.4/5; SD = 0.56) and desire for positive feelings after a genetic counseling session (mean score = 4.3/5; SD = 0.59). Participants who previously had genetic counseling felt less unsure about their diagnosis (p = 0.02) and had lower need for information about hEDS (p < 0.001). Majority of participants did not feel that their doctors were knowledgeable about hEDS (n = 269; 58%) and strongly supported a multidisciplinary approach to their care (n = 445; 97%). This research provides a framework for genetics providers and other healthcare professionals to assess the needs and expectations of patients with hEDS and consider re‐structuring their appointment formats to service this population. [ABSTRACT FROM AUTHOR]

Partial tetrasomy of distal 13q has a reported association with a variable phenotype including microphthalmia, ear abnormalities, hypotelorism, facial dysmorphisms, urogenital defects, pigmentation and skin defects, and severe learning difficulties. A wide range of mosaicism has been reported, which may, to some extent, account for the variable spectrum of observed phenotypes. We report here a pregnancy conceived using intrauterine insemination in a 32-year-old female with a history of infertility. Noninvasive prenatal screening (NIPS) was performed in the first trimester which reported an increased risk for trisomy 13. Follow-up cytogenetic workup using chorionic villus sampling (CVS) and amniotic fluid samples showed a mosaic karyotype with a small supernumerary marker chromosome (sSMC). Chromosomal microarray analysis (CMA) identified a mosaic 31.34 Mb terminal gain on chr13q31.1q34 showing the likely origin of the sSMC to distal chromosome 13q. Follow-up metaphase FISH testing suggested an inverted duplication rearrangement involving 13q31q34 in the marker chromosome and the presence of a neocentromere. At 21 months of age, the proband has a history of gross motor delay, hypotonia, left microphthalmia, strabismus, congenital anomaly of the right optic nerve, hemangiomas, and a tethered spinal cord. Postnatal chromosome analyses in buccal, peripheral blood, and spinal cord ligament tissues were consistent with the previous amniocentesis and CVS findings, and the degree of mosaicism varied from 25 to 80%. It is often challenging to pinpoint the chromosomal identity of sSMCs using banding cytogenetics. A combination of low-pass genome sequencing of cell-free DNA, chromosomal microarray, and FISH enabled the identification of the precise chromosomal rearrangement in this patient. This study adds to the growing list of clinically identified neocentric marker chromosomes and is the first described instance of partial tetrasomy 13q31q34 identified in a mosaic state prenatally. Since NIPS is now being routinely performed along with invasive testing for advanced maternal age, an increased prenatal detection rate for mosaic sSMCs in otherwise normal pregnancies is expected. Future studies investigating how neocentromeres mediate gene expression changes could help identify potential epigenetic targets as treatment options to rescue or reverse the phenotypes seen in patients with congenital neocentromeres. [ABSTRACT FROM AUTHOR]

Vacuolar ATPases (V-ATPases) are large multisubunit proton pumps conserved among all eukaryotic cells that are involved in diverse functions including acidification of membrane-bound intracellular compartments. The ATP6AP1 gene encodes an accessory subunit of the vacuolar (V)-ATPase protein pump. Pathogenic variants in ATP6AP1 have been described in association with a congenital disorder of glycosylation (CDG), which are highly variable, but often characterized by immunodeficiency, hepatopathy, and neurologic manifestations. Although the most striking and common clinical feature is hepatopathy, the phenotypic and genotypic spectrum of ATP6AP1-CDG continues to expand. Here, we report identical twins who presented with acute liver failure and jaundice. Prenatal features included cystic hygroma, atrial septal defect, and ventriculomegaly. Postnatal features included pectus carinatum, connective tissue abnormalities, and hypospadias. Whole-exome sequencing (WES) revealed a novel de novo in-frame deletion in the ATP6AP1 gene (c.230&#45232delACT;p.Tyr77del). Although both twins have the commonly reported clinical feature of hepatopathy seen in other individuals with ATP6AP1-CDG-related disorder, they do not have neurological sequelae. This report expands the phenotypic spectrum of ATP6AP1-CDG-related disorder with both probands exhibiting unique prenatal and postnatal features, including fetal ventriculomegaly, umbilical hernia, pectus carinatum, micropenis, and hypospadias. Furthermore, this case affirms that neurological features described in the initial case series on ATP6AP1-CDG do not appear to be central, whereas the prenatal and connective tissue manifestations may be more common than previously thought. This emphasizes the importance of long-term clinical follow-up and variant interpretation using current updated recommendations. [ABSTRACT FROM AUTHOR]

Objective: ITPR3, encoding inositol 1,4,5‐trisphosphate receptor type 3, was previously reported as a potential candidate disease gene for Charcot‐Marie‐Tooth neuropathy. Here, we present genetic and functional evidence that ITPR3 is a Charcot‐Marie‐Tooth disease gene. Methods: Whole‐exome sequencing of four affected individuals in an autosomal dominant family and one individual who was the only affected individual in his family was used to identify disease‐causing variants. Skin fibroblasts from two individuals of the autosomal dominant family were analyzed functionally by western blotting, quantitative reverse transcription PCR, and Ca2+ imaging. Results: Affected individuals in the autosomal dominant family had onset of symmetrical neuropathy with demyelinating and secondary axonal features at around age 30, showing signs of gradual progression with severe distal leg weakness and hand involvement in the proband at age 64. Exome sequencing identified a heterozygous ITPR3 p.Val615Met variant segregating with the disease. The individual who was the only affected in his family had disease onset at age 4 with demyelinating neuropathy. His condition was progressive, leading to severe muscle atrophy below knees and atrophy of proximal leg and hand muscles by age 16. Trio exome sequencing identified a de novo ITPR3 variant p.Arg2524Cys. Altered Ca2+‐transients in p.Val615Met patient fibroblasts suggested that the variant has a dominant‐negative effect on inositol 1,4,5‐trisphosphate receptor type 3 function. Interpretation: Together with two previously identified variants, our report adds further evidence that ITPR3 is a disease‐causing gene for CMT and indicates altered Ca2+ homeostasis in disease pathogenesis. [ABSTRACT FROM AUTHOR]

Myhre syndrome is an increasingly diagnosed rare syndrome that is caused by one of two specific heterozygous gain‐of‐function pathogenic variants in SMAD4. The phenotype includes short stature, characteristic facial appearance, hearing loss, laryngotracheal stenosis, arthritis, skeletal abnormalities, learning and social challenges, distinctive cardiovascular defects, and a striking fibroproliferative response in the ear canals, airways, and serosal cavities (peritoneum, pleura, pericardium). Confirmation of the clinical diagnosis is usually prompted by the characteristic appearance with developmental delay and autistic‐like behavior using targeted gene sequencing or by whole exome sequencing. We describe six patients (two not previously reported) with molecularly confirmed Myhre syndrome and neoplasia. Loss‐of‐function pathogenic variants in SMAD4 cause juvenile polyposis syndrome and we hypothesize that the gain‐of‐function pathogenic variants observed in Myhre syndrome may contribute to neoplasia in the patients reported herein. The frequency of neoplasia (9.8%, 6/61) in this series (two new, four reported patients) and endometrial cancer (8.8%, 3/34, mean age 40 years) in patients with Myhre syndrome, raises the possibility of cancer susceptibility in these patients. We alert clinicians to the possibility of detecting this syndrome when cancer screening panels are used. We propose that patients with Myhre syndrome are more susceptible to neoplasia, encourage increased awareness, and suggest enhanced clinical monitoring. [ABSTRACT FROM AUTHOR]

We report a case of a newly recognized primary immunodeficiency due to biallelic mutations in CARMIL2 manifesting as an actinic prurigo‐like photodermatitis, allergic diathesis and recurrent infections in a child. We present this case to highlight a rare phenotype seen in this T‐cell immunodeficiency and provide an overview of other dermatologic manifestations among published reports of this condition. [ABSTRACT FROM AUTHOR]

Background: Overlapping microdeletions of chromosome 3q26-3q28 have been reported in eight individuals. The common phenotype observed in these individuals include intrauterine growth restriction, short stature, microcephaly, feeding difficulties, facial dysmorphisms, limb abnormalities and developmental delay. The most striking clinical features shared among all reported cases is prenatal and postnatal growth restriction and neurodevelopmental abnormalities. Case presentation: We identified two additional individuals with overlapping deletions and shared clinical features by high-resolution SNP oligonucleotide microarray, and refined the smallest region of overlap (SRO) to a 1.2 Mb genomic location in chromosome 3q27.1 by reviewing and comparing all published cases. We evaluated the SRO using ACMG/ClinGen current recommendations for classifying copy number variants (CNVs), and discussed the contribution of the genes deleted in the SRO to the abnormal phenotype observed in these individuals. Conclusions: This study provides further evidence supporting the existence of a novel 3q27.1 microdeletion syndrome and suggests that haploinsufficiency of potential candidate genes, DVL3, AP2M1, and PARL in the SRO in 3q27.1 is responsible for the phenotype. [ABSTRACT FROM AUTHOR]

Background: The chromosome 3q29 microdeletion syndrome is characterized by a clinical phenotype that includes behavioral features consistent with autism and attention deficit hyperactivity disorder, mild to moderate developmental delay, language-based learning disabilities, and/or dysmorphic features. In addition, recent data suggest that adults with chromosome 3q29 microdeletions have a significantly increased risk for psychosis and neuropsychiatric phenotypes. Case presentation: We report a 3-year-old male with global developmental delay, anemia, and mild dysmorphic facial features. Clinical chromosomal microarray (CMA) testing of the proband detected a heterozygous 1.21 Mb deletion at chromosome 3q29, consistent with a diagnosis of the 3q29 microdeletion syndrome. Interestingly, subsequent parental testing determined that the pathogenic deletion was inherited from his otherwise healthy mother who had a history of learning disabilities. The chromosome 3q29 microdeletion was not detected in the healthy older sibling of the proband by CMA testing, nor was it prenatally detected in a subsequent maternal pregnancy. Conclusion: Our report highlights the 3q29 microdeletion syndrome as an illustrative example of the importance of a molecular diagnosis for families that harbor pathogenic copy number aberrations with variable expressivity, in particular those that also impart an increased risk for adult onset neuropsychiatric phenotypes. [ABSTRACT FROM AUTHOR]