Expanding the phenotypic spectrum of NOTCH1 variants: clinical manifestations in families with congenital heart disease.

Pathogenic variants in NOTCH1 are associated with non-syndromic congenital heart disease (CHD) and Adams-Oliver syndrome (AOS). The clinical presentation of individuals with damaging NOTCH1 variants is characterized by variable expressivity and incomplete penetrance; however, data on systematic phenotypic characterization are limited. We report the genotype and phenotype of a cohort of 33 individuals (20 females, 13 males; median age 23.

Building Healthy Babies: A Mixed-Methods Needs Assessment for a Pre-Conception Program in Ontario.

Objectives: The objective of this study was to gather Ontario clinicians' and public members' views on the design of a pre-conception patient education program.

Methods: In this mixed-methods study, online surveys comprised of rank order, multiple choice, and short answer questions were completed by clinicians and public members. Semi-structured focus groups consisting of 2-6 participants each were then held via videoconference.

Challenges experienced by genetic counselors while they provided counseling about mosaic embryos.

Objective: To survey genetic counselors (GCs) who have counseled about mosaic embryos regarding the challenges they faced in counseling this patient population and assess their need for more resources to support their practice.

Design: Self-administered online survey.

Setting: Academic university.

Mapping the cellular origin and early evolution of leukemia in Down syndrome.

Children with Down syndrome have a 150-fold increased risk of developing myeloid leukemia, but the mechanism of predisposition is unclear. Because Down syndrome leukemogenesis initiates during fetal development, we characterized the cellular and developmental context of preleukemic initiation and leukemic progression using gene editing in human disomic and trisomic fetal hematopoietic cells and xenotransplantation. GATA binding protein 1 () mutations caused transient preleukemia when introduced into trisomy 21 long-term hematopoietic stem cells, where a subset of chromosome 21 microRNAs affected predisposition to preleukemia.

Heterozygous NOTCH1 deletion associated with variable congenital heart defects.

Pathogenic heterozygous variants in the NOTCH1 gene are known to be associated with both left and right-sided congenital cardiac anomalies with strikingly incomplete penetrance and variable phenotypic expressivity. De novo NOTCH1 whole gene deletion has been reported rarely in the literature and its association with cardiac defects is less well established. Here, we report four cases of NOTCH1 gene deletion from two families associated with a spectrum of congenital heart defects from bicuspid aortic valve to complex cardiac anomalies.

Homozygous GLUL deletion is embryonically viable and leads to glutamine synthetase deficiency.

Glutamine synthetase (GS) is the enzyme responsible for the biosynthesis of glutamine, providing the only source of endogenous glutamine necessary for several critical metabolic and developmental pathways. GS deficiency, caused by pathogenic variants in the glutamate-ammonia ligase (GLUL) gene, is a rare autosomal recessive inborn error of metabolism characterized by systemic glutamine deficiency, persistent moderate hyperammonemia, and clinically devastating seizures and multi-organ failure shortly after birth. The four cases reported thus far were caused by homozygous GLUL missense variants.

The variability of SMARCA4-related Coffin-Siris syndrome: Do nonsense candidate variants add to milder phenotypes?

SMARCA4 encodes a central ATPase subunit in the BRG1-/BRM-associated factors (BAF) or polybromo-associated BAF (PBAF) complex in humans, which is responsible in part for chromatin remodeling and transcriptional regulation. Variants in this and other genes encoding BAF/PBAF complexes have been implicated in Coffin-Siris Syndrome, a multiple congenital anomaly syndrome classically characterized by learning and developmental differences, coarse facial features, hypertrichosis, and underdevelopment of the fifth digits/nails of the hands and feet. Individuals with SMARCA4 variants have been previously reported and appear to display a variable phenotype.

A large data resource of genomic copy number variation across neurodevelopmental disorders.

Copy number variations (CNVs) are implicated across many neurodevelopmental disorders (NDDs) and contribute to their shared genetic etiology. Multiple studies have attempted to identify shared etiology among NDDs, but this is the first genome-wide CNV analysis across autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), and obsessive-compulsive disorder (OCD) at once. Using microarray (Affymetrix CytoScan HD), we genotyped 2,691 subjects diagnosed with an NDD (204 SCZ, 1,838 ASD, 427 ADHD and 222 OCD) and 1,769 family members, mainly parents.

Microarray and RASopathy-disorder testing in fetuses with increased nuchal translucency.

Objectives: To determine the incidence of chromosomal abnormalities, submicroscopic chromosomal abnormalities and RASopathy-disorder (RD) pathogenic variants in a cohort of pregnancies with nuchal translucency thickness (NT) ≥ 3.5 mm, and to propose a clinical protocol for surveillance of this group of patients.

Methods: This was a retrospective chart review of patients referred to The Prenatal Diagnosis and Medical Genetics Program at Mount Sinai Hospital between January 2013 and December 2015, due to NT ≥ 3.

Impact of introduction of noninvasive prenatal testing on uptake of genetic testing in fetuses with central nervous system anomalies.

Objective: To evaluate the impact of introduction of noninvasive prenatal testing (NIPT) on the uptake of invasive testing in pregnancies complicated by fetal central nervous system (CNS) anomalies.

Methods: Retrospective review of all singleton pregnancies complicated by fetal CNS anomalies seen at a single tertiary center between 2010 and 2017. Cases who had undergone invasive testing or NIPT prior to the diagnosis of the CNS anomaly were excluded.

The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS.

TRPV6 Variants Interfere with Maternal-Fetal Calcium Transport through the Placenta and Cause Transient Neonatal Hyperparathyroidism.

Transient neonatal hyperparathyroidism (TNHP) is etiologically a heterogeneous condition. One of the etiologies is an insufficient maternal-fetal calcium transport through the placenta. We report six subjects with homozygous and/or compound-heterozygous mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6), an epithelial Ca-selective channel associated with this condition.

RAC1 Missense Mutations in Developmental Disorders with Diverse Phenotypes.

RAC1 is a widely studied Rho GTPase, a class of molecules that modulate numerous cellular functions essential for normal development. RAC1 is highly conserved across species and is under strict mutational constraint. We report seven individuals with distinct de novo missense RAC1 mutations and varying degrees of developmental delay, brain malformations, and additional phenotypes.

Genome-wide placental DNA methylation analysis of severely growth-discordant monochorionic twins reveals novel epigenetic targets for intrauterine growth restriction.

Background: Intrauterine growth restriction (IUGR), which refers to reduced fetal growth in the context of placental insufficiency, is etiologically heterogeneous. IUGR is associated not only with perinatal morbidity and mortality but also with adult-onset disorders, such as cardiovascular disease and diabetes, posing a major health burden. Placental epigenetic dysregulation has been proposed as one mechanism that causes IUGR; however, the spectrum of epigenetic pathophysiological mechanisms leading to IUGR remains to be elucidated.

Compound heterozygous mutations in the noncoding RNU4ATAC cause Roifman Syndrome by disrupting minor intron splicing.

Roifman Syndrome is a rare congenital disorder characterized by growth retardation, cognitive delay, spondyloepiphyseal dysplasia and antibody deficiency. Here we utilize whole-genome sequencing of Roifman Syndrome patients to reveal compound heterozygous rare variants that disrupt highly conserved positions of the RNU4ATAC small nuclear RNA gene, a minor spliceosome component that is essential for minor intron splicing. Targeted sequencing confirms allele segregation in six cases from four unrelated families.

De novo WNT5A-associated autosomal dominant Robinow syndrome suggests specificity of genotype and phenotype.

Robinow Syndrome (RS), a rare skeletal dysplasia syndrome, is characterized by dysmorphic features resembling a fetal face, mesomelic limb shortening, hypoplastic external genitalia in males, and renal and vertebral anomalies. Both autosomal dominant and autosomal recessive patterns of inheritance have been reported. Since the description of autosomal dominant Robinow Syndrome (ADRS; OMIM 180700) in 1969 by Meinhard Robinow and colleagues, the molecular etiology remained elusive until only recently.