as target cells in a 51 cr release assay with the ha 1 specific t cell clone as effector cells according to the cdna sequence analysis results the kg 1 cells were recognized by the ha 1 specific t cell clone data not shown this result suggested that the kiaa0223 gene forms a di allelic system of which the ha 1 h allele leads to recognition by the mhag ha 1 specific t cell clones two families who were previously typed for ha 1 with ha 1 specific ctl were studied on the cdna level for their kiaa0223 polymorphism the family members of family 1 were screened for their kiaa0223 sequence polymorphism by sequencing the ha 1 encoding sequence region all ha 1 negative members displayed the ha 1 r sequence whereas all ha 1 positive members turned out to be heterozygous thus carrying both ha 1 alleles fig3 a we subsequently designed ha 1 allele specific pcr primers to screen another family previously cellularly typed for ha 1 both parents and one child were determined as heterozygous for ha 1 two ha 1 negative children homozygous for the ha 1 r allele and one child homozygous for the ha 1 h allele fig3 b the screening of both families showed an exact correlation of the ha 1 phenotype as determined by recognition.