It has been shown that familial septo−optic dysplasia (SOD), a syndromic form of congenital hypopituitarism involving optic nerve hypoplasia and agenesis of midline brain structures, may be associated with homozygosity for an inactivating mutation in the homeobox gene hesx1/HESX1. Here, HESX1 is linked to non-acquired combined pituitary hormone deficiency.