Intellectual deficiency caused by BCAP31 mutations.

We report 17 novel families, 14 with intragenic BCAP31 variants (LoF and missense) and three with a deletion of BCAP31 and adjacent genes (comprising two CADDS patients, one male and one symptomatic female). Our study confirms the phenotype reported in males with intragenic LoF variants and shows that males with missense variants exhibit a milder phenotype. Most patients with a LoF pathogenic BCAP31 variant have permanent or transient liver enzyme elevation. We further demonstrate that carrier females (n = 10) may have a phenotype comprising LD, ID, and/or deafness.