Two Japanese Families with Pk Members

Abstract. Two individuals with the blood group P^k found in the Japanese population are reported, as well as the results of family studies. A second P^k sibling was found in the second family. Red cells from four members of the first family, who presumably were heterozygous for the gene responsible for P^k, showed no evidence of having a weaker P antigen. One of the two propositi gave birth to a baby, whose red cells gave a doubtful reaction in the direct antiglobulin test, but who showed neither clinical nor hematological signs of hemolytic disease of the newborn.