Mucolipidosis type IV (MLIV; MIM 252650) is an autosomal recessive lysosomal storage disorder that is characterized by corneal clouding, delayed psychomotor development, and mental retardation that usually presents during the first year of life [1]. Another interesting clinical characteristic is that patients are constitutively achlorhydric with associated hypergastremia [2]. Patients with MLIV do not show mucopolysaccharide excretion, skeletal changes, or organomegaly like the other mucolipidoses. Abnormal lysosomal storage bodies and large vacuoles have been found in skin and conjuctival biopsies using electron-microscopy and, prior to gene identification, served as the only means of diagnosis [3-5]. A recent report estimates that the carrier frequency of MLIV in the Ashkenazi Jewish population is 1 in 100, and mutations have been reported in Jewish and non-Jewish families [6-9].