The Genetic Architecture of Congenital Diarrhea and Enteropathy (CODE)

Next-generation sequencing (NGS) has supported precision therapeutic approaches that have improved the lives of children with rare diseases. Patients with congenital diarrhea and enteropathies (CODE) have a particularly difficult disease with high morbidity and mortality. However, there are now several targeted therapies including specific diets, pharmacological treatments, and surgical interventions that are based on an individual’s genetic diagnosis. We performed NGS on a large cohort of 139 infants with suspected monogenic congenital diarrheal disorders and identified known causal variants in 50% of cases, including a new founder NEUROG3 variant. We also uncovered and functionally characterized three novel CODE genes, GRWD1, MYO1A, and MON1A, using cell and zebrafish models. To investigate the role of grwd1 in the development of congenital diarrhea and enteropathies, we generated grwd1 knockout zebrafish and found that all F0 were lethal. Therefore we used first generation (F0) mosaic grwd1 mutant zebrafish using CRISPR (crispants). We then performed gene expression profile analysis using data obtained from RNAseq from wild type zebrafish line, and grwd1 crispants at 8 days post fertilization (dpf). Comparative gene expression profiling analysis between wt and grwd1zebrafish mutant were performed to examine the transcriptomic alterations caused by grwd1 deficiency.