Multiple, independent, common variants at RET, SEMA3 and NRG1 gut enhancers specify Hirschsprung disease risk in European ancestry subjects.

Purpose: Hirschsprung disease (HSCR) is a developmental disorder of the enteric nervous system (ENS) characterized by congenital aganglionosis arising from coding variants in ENS genes causing partial or total loss-of-function. Low-penetrance, common, noncoding variants at RET, SEMA3 and NRG1 loci are also associated with HSCR, with small-to-moderate loss of gene expression mediated through sequence variants in cis-regulatory elements (CRE) as another causal mechanism. Since these latter variants are common, many individuals carry multiple risk variants.

Gene- and tissue-level interactions in normal gastrointestinal development and Hirschsprung disease.

The development of the gut from endodermal tissue to an organ with multiple distinct structures and functions occurs over a prolonged time during embryonic days E10.5-E14.5 in the mouse.

Testing the Ret and Sema3d genetic interaction in mouse enteric nervous system development.

For most multigenic disorders, clinical manifestation (penetrance) and presentation (expressivity) are likely to be an outcome of genetic interaction between multiple susceptibility genes. Here, using gene knockouts in mice, we evaluated genetic interaction between loss of Ret and loss of Sema3d, two Hirschsprung disease susceptibility genes. We intercrossed Ret and Sema3d double null heterozygotes to generate mice with the nine possible genotypes and assessed survival by counting various genotypes, myenteric plexus presence by acetylcholinesterase staining and embryonic day 12.

Enhancer Variants Synergistically Drive Dysfunction of a Gene Regulatory Network In Hirschsprung Disease.

Common sequence variants in cis-regulatory elements (CREs) are suspected etiological causes of complex disorders. We previously identified an intronic enhancer variant in the RET gene disrupting SOX10 binding and increasing Hirschsprung disease (HSCR) risk 4-fold. We now show that two other functionally independent CRE variants, one binding Gata2 and the other binding Rarb, also reduce Ret expression and increase risk 2- and 1.

Loss of δ-catenin function in severe autism.

Autism is a multifactorial neurodevelopmental disorder affecting more males than females; consequently, under a multifactorial genetic hypothesis, females are affected only when they cross a higher biological threshold. We hypothesize that deleterious variants at conserved residues are enriched in severely affected patients arising from female-enriched multiplex families with severe disease, enhancing the detection of key autism genes in modest numbers of cases. Here we show the use of this strategy by identifying missense and dosage sequence variants in the gene encoding the adhesive junction-associated δ-catenin protein (CTNND2) in female-enriched multiplex families and demonstrating their loss-of-function effect by functional analyses in zebrafish embryos and cultured hippocampal neurons from wild-type and Ctnnd2 null mouse embryos.

Generation of a cre recombinase-conditional Nos1ap over-expression transgenic mouse.

Polymorphic non-coding variants at the NOS1AP locus have been associated with the common cardiac, metabolic and neurological traits and diseases. Although, in vitro gene targeting-based cellular and biochemical studies have shed some light on NOS1AP function in cardiac and neuronal tissue, to enhance our understanding of NOS1AP function in mammalian physiology and disease, we report the generation of cre recombinase-conditional Nos1ap over-expression transgenic mice (Nos1ap (Tg)). Conditional transgenic mice were generated by the pronuclear injection method and three independent, single-site, multiple copies integration event-based founder lines were selected.