A further study on the polymorphism of placental alkaline phosphatase in Japanese

Polymorphism of placental alkaline phosphatase (PL) was investigated in 120 Japanese placentae by means of starch gel electrophoresis and an improved staining method for the isoenzymes using naphthol AS-MX phosphate as substrate instead of beta-naphthyl phosphate. The present method gave more satisfactory results for the detection of the PL bands. Besides five of the six common phenotypes three different uncommon variants were identified. The gene frequencies of PL types were estimated at PL1 = 0.729, PL2 = 0.054, PL3 = 0.200 and PLv = 0.017, which were very similar to those reported in other districts of Japan.