A novel HLA-B*14 allele - B*14:53 - genetics and serology

HLA-B*14:53 was found in a UK European normal blood donor prior to registration on the Welsh Bone Marrow Donor Registry. It differs from B*14:13 by one base (103G>T) in exon 2 resulting in a substitution of alanine (A) in B*14:13 to serine (S) in B*14:53. Unique among current HLA-B*14 alleles, B*14:53 and B*14:13 share a motif of 59 bases between positions 361 and 419 in exon 3. This motif is present in numerous HLA-B alleles the commonest overall being B*08:01, suggesting that both B*14:53 and B*14:13 arose from intralocus gene conversion events with B*08:01. Thus, B*14:53 probably arose from B*14:01:01 (which has TCC at codon 11 (S), while B*14:13 arose from B*14:02:01:01 which has GCC at codon 11 (A). Additionally, the two likely B*14:53-bearing and B*14:13-bearing haplotypes are typical of B*14:01:01-bearing and B*14:02:01:01-bearing haplotypes, respectively. Serological testing, using 49 antisera with HLA-B64, or B64, B65 reactivity, showed that the B*14:53 specificity did not react as a B64 (B*14:01) specificity and may appear as a short/weak HLA-B14. This implies that residues additional to S at position 11 are involved in HLA-B64 serological identity; for example, the motif 11S 97W 116F is possessed by B*14:01 and many other B*14 products (and B*39:79 plus some HLA-C products) but not B65 (B*14:02) or the B*14:53 specificity. B*14:53 was found in a random HLA sequence-based typed population of 32 530 normal subjects indicating a low precision allele frequency of 0.000015 in subjects resident in Wales.