Characterization of 40 novel HLA class I and class II alleles identified in umbilical cord blood units.

Forty novel HLA class I and class II alleles were identified in umbilical cord blood (UCB) samples and categorized based on various types of mutations: non-synonymous, synonymous, frameshift, and premature termination codon. This study described 14 novel HLA-A alleles, 9 novel HLA-B alleles, 4 novel HLA-C alleles, 3 novel HLA-DRB1 alleles and 10 novel HLA-DQB1 alleles. Comparing the new allele sequence with the most homologous sequence, 60% of the novel alleles exhibited non-synonymous substitution, 32.5% observed with synonymous substitution, 5% displayed premature stop codon, and 2.5% presented with frameshift mutation. The majority of the new alleles contained a single nucleotide variation when compared with the most similar sequence.