[Identification of a case with novel HLA-DRB1*12:106 allele]

To identify the nucleotide sequence of a novel HLA-DRB1*12:106 allele.

A blood donor who was joined into the database for platelet matching transfusion at the Blood Center of Zhejiang Province in 2023 was selected as the study subject. HLA genotyping was carried out through next-generation sequencing based on AllType NGS 11 locus, AllType FASTPlex NGS reagents, and Sanger sequencing method. The HLA genotype of the donor by Sanger sequencing and next generation sequencing were assigned by using uTYPE 7.3 and TypeStream Visual 3.0 software, respectively. This study was approved by Medical Ethics Committee of the Zhejiang Blood Center (Ethics No. Provincial Blood Center Ethics Review 2022 Research No. 001).

A novel HLA-DRB1*12 allele has been identified, and the full coding sequence has been submitted to the GenBank database (No. OR101190), and the length of submitted sequence was 801 bp, which was officially named as HLA-DRB1*12:106 by the WHO Nomenclature Committee for Factors of the HLA System (submission No. HWS10066755). Compared with the sequence of the highest homology (HLA-DRB1*12:01:01:01 allele), a single nucleotide change was identified at position 344 T>G in the exon 2 of the HLA-DRB1*12:106, which has resulted in replacement of Valine by Glycine at residue 86. The HLA genotype of the proband was determined as HLA-A*02:01, 11:01;-B*13:02, 40:01;-C*01:02, 03:03;-DRB1*07:01, 12:106;-DRB3*01:01;-DRB4*01:03;-DQA1*02:01,04:01;-DQB1*02:02,04:02;-DPA1*01:03,01:03; -- DPB1*02:01:02G,04:01:01G.

A novel HLA-DRB1 allele has been identified in the Chinese population. The mutated amino acid, located in the peptide binding region of the β chain, may affect the binding characteristics of antigen peptides.