RABEP1

The protein acts as a Rab effector that links gamma-adaptin with RAB4A and RAB5A to facilitate endocytic membrane fusion, recycling endosome trafficking, and transport of protein complexes including ion channels and polycystin proteins to the cilium. Biallelic pathogenic variants cause Martsolf syndrome, an autosomal recessive disorder characterized by congenital cataracts, intellectual disability, hypogonadism, and distinctive facial features. This gene is highly constrained against loss-of-function variants (pLI 0.998, LOEUF 0.266), indicating that complete protein loss is likely incompatible with normal development.