Pyrimidine 5'-nucleotidase deficiency: studies of five cases in two Japanese families.

Two new families with red cell pyrimidine 5'-nucleotidase (P5N) deficiencies were found in Japan. The enzyme activities were 4.8% in case 1 and 9.7% in case 2. The propositi showed characteristic hemolytic anemia with market basophilic stippling, increased reduced glutathione content and accumulation of pyrimidine nucleotides in the red cell. High Michaelis constants for cytidine monophosphate, normal thermostability, abnormal optimum pH in both cases, and normal electrophoretic mobility in case 1 and slower mobility in case 2 were shown, suggesting that the cause of P5N deficiency, at least in these cases, is due to the structural gene mutation.