Abstract:

An unknown HLA-B allele which was similar to HLA-B*270401 was detected by FLOW-SSO、PCR-SSP and heterozygous sequence-based typing (SBT) in Chinese Han individual. Its anomalous patterns suggested the possible presence of new allele. Amplifying exon 2-5(include intron 2-4) of the HLA-B*27 allele separately by using allele-specific primers and sequencing in both directions. Identifying the difference between the novel B*27 allele and B*270401. The sequence of novel B*27 from exon 2 to partial exon 5 is 1 815 bp. There are 10 nt changes from B*270401 in exon 3-4, at nt634where A→C(codon130 AGC→CGC, 130 S→R); nt670 where A→T (codon142 ACC→TCC, 142 T→S); nt683 where G→T (codon146 TGG→TTG, 146 W→L); nt698 where A→T (codon151 GAG→GTG, 151 E→V); nt774 where G→C (codon176 GAG→GAC, 176 E→D); nt776 where C→A (codon177 ACG→AAG, 177 T→K); nt781 where C→G (codon179 CAG→GAG, 179Q→E); nt789 where G→T (codon181 GCG→GCT) resulting no coding change; nt1438 where
C→T (codon206 GGC→GGT) resulting no coding change; nt1449 where G→C (codon210 GGG→GCG, 210G→A). In IMGT/HLA database, only three alleles (B*270502/2706/2732) have sequences of introns. The same sequence in intron 2 showed homology between the novel HLA-B*27 allele and B*2706, but their homology could not be supported in intron 3-4. Comparing the sequence of the novel B*27 allele in intron 3 and 4 with B*27 group, it showed there are three mutations at nt106 C→G, nt179 G→A, nt536 G→A and one deletion at nt168 in intron 3 and one mutations at nt82 T→C in intron 4, but the sequence of the novel B*27 allele in intron 3 and 4 was all the same to B*070201. The sequence was submitted to Gen-Bank and the accession number was DQ915176. The allele has been confirmed as an extension of B*2736 by the WHO Nomenclature committee in November 2006.