The Minor Histocompatibility Antigen HA-1: A Diallelic Gene with a Single Amino Acid Polymorphism

Abstract
The minor histocompatibility antigen (mHag) HA-1 is the only known mHag for which mismatching is correlated with the development of severe graft versus host disease (GvHD) after human leukocyte antigen–identical bone marrow transplantation. HA-1 was found to be a nonapeptide derived from an allele of the KIAA0223gene. The HA-1–negative allelic counterpart encoded byKIAA0223 had one amino acid difference from HA-1. Family analysis with HA-1 allele-specific polymerase chain reaction showed an exact correlation between this allelic polymorphism and the HA-1 phenotype. HA-1 allele typing of donor and recipient should improve donor selection and allow the determination of bone marrow transplantation recipients with high risk for HA-1–induced GvHD development.