Biochemical Comparisons of the Adult and Childhood Forms of Cystinosis

Abstract

Three unrelated adult patients with cystinosis were studied in an attempt to explain the differences in the clinical manifestations of childhood and adult cystinosis. The free cystine content of both leukocytes and fibroblasts from the adult patients averaged 30 to 50 times higher than normal and were intermediate between the values in these tissues from persons heterozygous and homozygous for childhood cystinosis. As in leukocytes and fibroblasts from children with cystinosis, the cystine was localized in a subcellular compartment that has not yet been identified. The intracellular deposits of free cystine in adult and childhood cystinotic fibroblasts appeared to be unavailable for sustaining normal metabolism since neither cell type was viable in a cystine-free medium.