Cystathioninuria in Down's syndrome.

Secondary cystathioninuria is associated with various pathological conditions (Gjessing, 1963; Gjessing & Mauritzen, 1965; Endres & Wuttge, 1978). In many cases, cystathioninuria has been associated with mental retardation (Harris et al., 1959; Robb et al., 1984). As far as the authors know, cystathioninuria has not previously been described in Down's syndrome. In 1981, in the author's institution for the mentally retarded, all patients with Down's syndrome were screened with regard to aminoaciduria, using thin layer chromatography. In the course of this process, a case of cystathioninuria was discovered. The results are presented in detail.