Frequency of erythrocyte pyruvate kinase deficiency in Chinese infants

The incidence of deficiency of the enzyme pyruvate kinase (PK) in Chinese infants was determined. Both the standard assay of erythrocyte pyruvate kinase enzyme activity and a fluorescent screening test (standardized) were used. The results of these two tests were compared. Of 1,159 infant cord blood samples studied, 26 (or 2.2%) had abnormally low levels of PK activity using the screening test, as did 24 of the samples tested by the enzyme assay. The results indicate that the frequency of a defective PK gene in the population of Guangzhou is significantly lower (p less than .05) than the previously reported defective gene frequency of 3.4% in Hong Kong. They also demonstrate the critical importance of standardization of the screening test, if most accurate estimates of gene frequency are to be derived by using this test.