Cystinuria: Increased Prevalence in Patients with Mental Disease

Abstract The prevalence of homozygous cystinuria was studied in two populations. One group comprising 4714 persons represented patients found in the general medical population, and the other (1400 subjects) was drawn from a hospital for patients with mental illness or retardation. The prevalence of homozygous cystinuria in the general population is estimated to be about 10–4 when derived from the frequency of heterozygotes. The expected frequency of homozygous cystinuria in the population with mental disease is similar when derived by the same method. However, the observed frequency of homozygous cystinuria in the latter population is actually greater than 10–3, a value significantly higher than in the general population (p less than 0.02). This finding confirms a suspicion that cystinuric patients are at higher risk for impaired cerebral function.