Hanchard, Neil A.

Introduction: Bicuspid Aortic Valve (BAV), the most common adult congenital heart defect, is a major cause of aortic insufficiency or stenosis requiring valve replacement and thoracic aortic aneurysms predisposing to acute aortic dissections. The spectrum of BAV ranges from early onset valve and aortic complications to sporadic late onset disease. We determined the frequency and gene content of rare genomic copy number variants (CNVs) in isolated BAV cases. Methods: We performed genome-wide SNP microarray analysis of familial BAV cases with early onset complications in the UTHealth BAV Research Registry (EBAV, n=394) and elderly probands from the International BAV Consortium (BAVCON, n=4216). CNVs were detected in Illumina genotypes using the PennCNV, QuantiSNP and cnvPartition algorithms. BAV cases were compared to 16,576 controls without known cardiovascular disease from the Database of Genotypes and Phenotypes. Only CNV calls with >6 consecutive variants, >20 kb in length, identified by at least two algorithms and intersected with known genes were included. For comparison, we assessed a cohort with left ventricular outflow tract obstructive lesions including BAV (LVOTO, n=1561) using identical methods. CNV burden and associations were tested using PLINK. Results: We identified 84 large recurrent CNVs in BAV cases that are absent or rare (<0.1%) in controls. 34 rare CNVs overlap between BAV and LVOTO cases and involve candidate genes that interact with each other during heart development. The largest and most prevalent of the recurrent CNVs are 8p23 duplications involving GATA4 (OR 340, CI: 42-2700). CNVs of genes that cause BAV when mutated were significantly enriched in cases (n=135, P =1x10 -27 ). The overall burden of rare genic CNVs, specifically large deletions, was also increased in BAV cases (empiric P < 1x10 -5 ) and was higher in younger EBAV cases than in older BAVCON cases. Conclusion: We identified likely pathogenic CNVs in more than 10% of BAV cases, implicating alterations of candidate genes at these loci in the pathogenesis of BAV.

Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B , which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.

AbstractCSNK2B has recently been implicated as a disease gene for neurodevelopmental disability (NDD) and epilepsy. Information about developmental outcomes has been limited by the young age and short follow‐up for many of the previously reported cases, and further delineation of the spectrum of associated phenotypes is needed. We present 25 new patients with variants in CSNK2B and refine the associated NDD and epilepsy phenotypes. CSNK2B variants were identified by research or clinical exome sequencing, and investigators from different centers were connected via GeneMatcher. Most individuals had developmental delay and generalized epilepsy with onset in the first 2 years. However, we found a broad spectrum of phenotypic severity, ranging from early normal development with pharmacoresponsive seizures to profound intellectual disability with intractable epilepsy and recurrent refractory status epilepticus. These findings suggest that CSNK2B should be considered in the diagnostic evaluation of patients with a broad range of NDD with treatable or intractable seizures.