Clinical and Biochemical Observations in Two Cases of Hartnup Disease

Abstract

The present paper describes 2 new cases of Hartnup disease from unrelated families. The characteristic abnormalities of L-tryptophan metabolism after oral loading are observed in both cases and agree with the data of Milne et al. (1960). Intravenously administered tryptophan is normally metabolized. The parents have a significantly lower plasma tryptophan level 2 hr. after oral loading, suggesting that they have a partial defect in tryptophan absorption. This supports the hypothesis that Hartnup disease is an autosomal recessive abnormality. Present observations confirm the theory that a defective transport of tryptophan in the intestine and the renal tubules is the primary abnormality in Hartnup disease.