Analysis of full-length sequence and 18 point mutations of HLA-B in a leukemia patient and her family / 中国组织工程研究

ABSTRACT

BACKGROUND: The human leukocyte antigen (HLA) has undergone long-term evolution to form diverse polymorphisms. In recent years, due to the increase in the number of examinees and the rapid development of HLA typing technology, novel HLA alleles have been discovered constantly. OBJECTIVE: To analyze the full-length sequence and 18 point mutations of HLA-B gene in a leukemia patient and her family using the next-generation sequencing technology. METHODS: Polymerase chain reaction and sequence-specific oligonucleotide probes (PCR-SSOP) and polymerase chain reaction-sequence based typing (PCR-SBT) revealed abnormalities in the patient’s HLA-B. To identify the genotype, we sequenced the full length of the gene by next-generation sequencing technology and collected blood samples from the patient’s father, mother and two sisters for genetic analysis of HLA genes. RESULTS AND CONCLUSION: Both PCR-SSOP and PCR-SBT indicated that the HLA-B sample had no perfectly matched genotype. Further detection using the next-generation sequencing technology revealed that the novel allele had 18 base mutations in the exon, intron and 3’UTR compared to the most homologous allele B*150901. Five exon base mutations were located in the exons 3 and 4, which were 486G→C, 583T→C, 636T→C, 652A→G, 756C→T, resulting in changes in the five corresponding codons, including 171 tyrosine (Tyr) → histidine (His) and 194 isoleucine (Ile) → valine (Val). A pedigree survey found that the patient’s novel HLA B allele was inherited from her father. The novel allele sequence was submitted to the Genbank database (MG595995). A novel HLA-B allele was confirmed by the next-generation sequencing, which was officially named HLA-B*15435 by the World Health Organization HLA Factor Nomenclature Committee in December 2017.