Simultaneous mutations in exon and intron of a novel human leukocyte antigen-B*3818 allele revealed by genomic sequence analysis / 中华检验医学杂志

ABSTRACT

Objective To analysis the genomic sequence of a novel human leukocyte antigen (HLA)-B*3818 allele.Methods Full length genomic sequence of an unknown HLA-B allele was cloned,followed by bi-directional sequencing and the specificity of the antigen coded by this novel allele was defined by microcytotoxicity assay.The frequency and haplotype of this novel allele was acquired by population census and parentage analysis.Results The full length genomic sequence of this novel HLA-B*3818 allele with accession number FJ561482 differs from HLA-B*380201 by two nucleotide changes in exon 4 and intron 5,respectively.One change is located at nt 660 in exon 4 where C→A alternation,which results in an amino acid substitution from Asp(GAC)to Glu(GAA)at codon 196.This alternation is a new single nucleotide polymorphism compared with all other HLA-B alleles.Another is located at genomic position 2133 in intron 5(A→C).Except for this substitution,the intron sequences of HLA-B*3818 allele are identical to those of other HLA-B*38 alleles including HLA-B*380101,B*380201 and B*3814.The serological specificity of HLA-B*3818 is B38 and the frequency of this new allele is less than 0.000 5 in Chinese Han population.The parentage analysis showed the haplotype of novel allele is A*030101-Cw*010201-B*3818-DRB1*1312-DOB1*060101.Conclusion The simultaneous mutations in exon and intron were found in the Hovel HLA-B*3818 allele,and so it can present more sequence information for studies and applications associated with HIA genes by analyzing the genomic sequences of novel HLA alleles.