Clinical and Biochemical Observations in Two Cases of Hartnup Disease

Hartnup disease, first described by Baron, Dent, Harris, Hart, and Jepson (1956), is characterized by a photosensitive pellagra-like rash, cerebellar ataxia, generalized renal aminoaciduria, hyperindoluria, and hypertryptophanuria.Nemeth and Nachmias (1958) suggested that in this disorder there might be a deficiency of tryptophan pyrrolase, the enzyme that catalyses tryptophan to formylkynurenine.Milne, Crawford, Girao, and Loughridge (1960) produced evidence that there was an impairment of tryptophan absorption in the intestine in addition to that observed in the renal tubules.The abnormally high urinary output of indolic metabolites was demonstrated by Asatoor, Craske, London, and Milne (1963) to be the result of normal bacterial action on the unabsorbed tryptophan in the intestine and not the result of an abnormal intestinal flora.de Laey, Hooft, Timmermans, and Snoeck (1964) using intravenous tryptophan loading tests, were able to show that intravenously administered tryptophan was metabolized by a Hartnup patient in a similar manner to the control.The evidence accumulated to date suggests that the primary abnormality in Hartnup disease is a defective transport of trypto- phan, and probably other neutral amino acids, in the small intestine and renal tubules.A total of 19 cases has been reported since the original description (Baron et al.