A Japanese family with unusual segregation of GM phenotype: a GM silent allele?

A Japanese family with unusual segregation of GM phenotype was found in connection with a case of disputed paternity. Typing for 27 hemogenetic marker systems revealed apparent nonmaternity in the GM system alone. When tested for 14 GM allotypes, the alleged father, the mother, and the child were of the GM A,F,Z N B0,1,3,4,5,S,T,U; GM A,Z N' G,U; and GM A,Z N' B0,3,5,S,T types, respectively. The results of a family study strongly suggested that a GM silent allele was responsible for the apparent nonmaternity; however, definitive evidence could not be obtained.