HLA-A24 is the second most frequently expressed HLA-A type in Koreans (GF 22.8%). Four different serologic
reaction patterns were observed in Korean A24 positive samples using a commercial serologic typing kit.
To clarify the nature of serologic heterogeneity, thirteen A24 positive DNA samples representing the four
different serologic reaction patterns were subjected to DNA sequencing analysis of the amplified HLA-A genes
from each sample. Four A*24 alleles (A*2402101, A*2403, A*2408, and A*2421) were associated with the four
unique serologic reaction patterns. During this study, a novel allele, A*2421, was characterized. The new
sequence is similar to A*2402101, differing at codon 127 (AAA→AAC; K→N). By comparing putative amino
acid sequences and serologic reaction patterns of A*24 allelic products identified in this study, several
crucial sites for A24- and A9-specific antibody binding were predicted: 127K for A24 antibody binding,
and 62E-65G and 166D-167G for A9 antibody binding. This information will be helpful for accurately assigning
HLA-A24 types by serology and for predicting serologic types of new alleles.
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