Rare phenotypes of placental alkaline phosphatase an analysis of relationships with some neonatal and maternal variables

Placental alkaline phosphatase (Pl) polymorphism is due to the occurrence of three common alleles and more than fifteen rare ones at an autosomal locus. The high number and frequency (about 2%) of rare Pl alleles represent a very special case among polymorphic enzymes. Since the Pl gene is also special in that it is active only during intrauterine life, the allelic diversity and its maintenance may be connected with intrauterine environment and with fetal development.