抄録
Glucose-6-phosphate dehydrogenase (G6PD) in erythrocyte was determined in two patients with Klinefelter's syndrome. It showed a significantly higher activity, especially in a patient of XXXXY type of the syndrome, than normal range. This result suggests that an excess of genetic material from the X chromosome is responsbile for higher activity of the erythrocyte G6PD in Klinefelter's syndrome.