HLA-A24 DIVERSITY INCLUDING A NOVEL ALLELE (A*2421) IN KOREANS.
KW Lee, JS Lee, JY Park, HC Cho, Department of Clinical Pathology, College of Medicine, Hallym University, Seoul, Korea.

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HLA-A24 has known to be one of the most popular and diverse groups of HLA-A molecule in the human population. Although A24 is second frequently expressed HLA-A types in Koreans (GF 22.8%), this allele family has not been well studied in the population. Four different serologic reaction patterns were observed in Korean A24 positive samples using the commercial serologic typing kit. To clarify their nature of serologic heterogeneity, seven A24 positive unrelated DNA samples representing each serologic reaction patterns were subjected to DNA sequencing analysis of the amplified HLA-A genes from each sample. Four different A24 alleles (A*2402, A*2403, A*2408, and A*2421) were identified and each appeared to be correlated with a unique serologic reaction pattern. In this process, a novel allele, A*2421, was characterized. The new sequence is similar to A*2402, differing at codon 127 (AAAa AAC; Ka N). Sequence was confirmed by sequencing of cloned PCR amplicon obtained from a sibling exhibiting same unusual serologic reaction pattern. In addition, PCR-SSP typing using PCR primers derived from codon 127 confirmed its unusual sequence. This information will be helpful in accurate assignment of HLA-A24 related types by serology as well as in determining the strategy for establishing DNA typing for this population