Neurological disease in a child with carnosinase deficiency

Carnosinase deficiency presented as a progressive neurological problem with sensory polyneuropathy in a 12-year-old male. Carnosinuria was present, even on a meat-free diet, although carnosinemia was not observed. An increased amount of unmetabolized carnosine was found in the urine after a carnosine load. Serum and tissue (liver and nerve) from the patient showed deficient carnosinase activity. Morphometric and fine structural studies on the nerve and skin biopsies are presented, as is a review of the literature on carnosinase deficiency in mentally retarded patients.