Whole genome analysis of an extended pedigree with Prader–Willi Syndrome, hereditary hemochromatosis, and dysautonomia-like symptoms

This report includes the discovery and analysis of a pedigree with Prader–Willi Syndrome (PWS), hereditary hemochromatosis (HH), and dysautonomia-like symptoms. Nine members of the family participated in whole genome sequencing (WGS), which enabled a wide scope of variant calling from single-nucleotide polymorphisms to copy number variations. First, a 5.5 Mb de novo deletion is identified in the chromosome region 15q11.2 to 15q13.1 in the boy with PWS. Second, a female invididual with HH is homozygous for the p.C282Y variant in HFE, a mutation known to be associated with HH. Her brother is homozygous for the same variant, although he has yet to be clinically diagnosed with HH. Third, none of the people with dysautonomia-like symptoms carry any reported or novel rare variants in IKBKAP that are implicated in familial dysautonomia (FD - HSAN III). Although two people with dysautonomia-like symptoms carry two heterozygous variants in NTRK1, a gene that has been shown to contribute to HSAN IV (congenital insensitivity to pain with anhidrosis, a disease that closely resembles FD), this variant is not present in the third proband. Fourth, WGS revealed pharmacogenetic variants influencing the metabolism of warfarin and simvastatin, which are being routinely prescribed to the proband. Finally, reports of the phenotypes were standardized with the Human Phenotype Ontology annotation, which may facilitate the search for other families with similar phenotypes. Due to the extreme heterogeneity and insufficient knowledge of human diseases, it is of crucial importance that both phenotypic data and genomic data are standardized and shared.