No preferential mode of inheritance for highly constrained genes.

Genetic constraint metrics such as the gnomAD probability of being loss-of-function (LoF) intolerant (pLI) are used to prioritize candidate genes but the mode of inheritance of highly constrained genes has never specifically been studied. We compared 605 genes with a pLI of 1 (pLI1 group) with a random sample of 635 genes from gnomAD (the random group) in terms of genetic constraint metrics, associations with Mendelian disease, modes of inheritance, and two intragenic constraint scores: the percentage of constraint coding regions (CCR) in the 99th percentile and the gene variation intolerance rank (GeVIR). The proportion of genes associated with a Mendelian disease was 35.9% (217/605) in the pLI1 group and 19.5% (124/635) in the random group (p < 0.0001). The modes of inheritance in the random group were autosomal dominant for 35 genes (28.2%), autosomal recessive for 69 (55.6%), mixed for 14 (11.3%) and X-linked for 6 genes (4.8%). The corresponding distribution in the pLI1 group was 150 (69.1%), 26 (12.0%), 14 (6.5%) and 27 (12.4%) (p < 0.0001). The percentage of CCRs in the 99th percentile was 0.3 in the random group versus 1.12 in the pLI1 group (p < 0.0001). The GeVIR score was 50.9 for the random group versus 15.1 for the pLI1 group (p < 0.0001). High genetic constraint does not seem to be associated with a particular mode of inheritance but does seem to be associated with the intragenic constraint scores considered here. Some highly constrained genes are associated with two different modes of inheritance.