Vitamin A deficiency due to bi-allelic mutation of RBP4: There's more to it than meets the eye.

Vitamin A deficiency is the leading cause of preventable blindness in children worldwide and results in a well-recognized ocular phenotype. Herein we describe a patient presenting to the eye clinic with a retinal dystrophy and ocular colobomata. This combination of clinical signs and consanguineous pedigree structure suggested a genetic basis for the disease, a hypothesis that was tested using whole genome sequencing. Bi-allelic mutations in RBP4 were identified (c.248+1G>A), consistent with a diagnosis of inherited vitamin A deficiency. We describe a constellation of signs that appear to be characteristic for this disease, increasing clinical awareness of this rare condition.