Inheritance of PiM subtypes. A study of 151 families with a total of 242 children and of 142 mother-child pairs.

Pi phenotypes were classified by isoelectric focusing in sera of 151 families with a total of 242 children and in sera of 142 mother-child pairs. The six common subtypes of PiM are genetically determined by three alleles named PiM1, PiM2, and PiM3. No exceptions to the postulated mode of inheritance have been found. The possibility of further heterogeneity of the intermediate variant PiM3 is discussed.