How to read the HLA allele nomenclature
The standardized HLA gene and allele nomenclature is managed by the WHO Nomenclature Committee for Factors of the HLA System. A high-level summary of their nomenclature system is reproduced here for easy reference. A thorough and detailed review of the HLA naming schema is available online.
Fig. 1
Fig. 1 shows the standard naming convention for HLA alleles. It includes the HLA gene name, the HLA allele group for a specific gene, a specific non-synonymous allele (i.e. one that changes a protein amino acid sequence), a specific synonymous allele (i.e. one that does not change a protein amino acid sequence), non-CDS (coding sequence) alleles (i.e. introns, 5′-UTR’s, 3′-UTR’s, etc.) and suffixes that denote protein expression level.
| HLA Field | Definition |
|---|---|
| HLA | The HLA region and prefix for an HLA gene |
| HLA-DRB1 | A particular HLA locus i.e. DRB1 |
| HLA-DRB1*13 | A group of alleles that encode the DR13 antigen or sequence homology to other DRB1*13 alleles |
| HLA-DRB1*13:01 | A specific HLA allele |
| HLA-DRB1*13:01:02 | An allele that differs by a synonymous mutation from DRB1*13:01:01 |
| HLA-DRB1*13:01:01:02 | An allele that contains a mutation outside the coding region from DRB1*13:01:01:01 |
| HLA-A*24:09N | A 'Null' allele. An allele that is not expressed |
| HLA-A*30:14L | An allele that encodes a protein with significantly reduced or 'Low' cell surface expression |
| HLA-A*24:02:01:02L | An allele that encodes a protein with significantly reduced or 'Low' cell surface expression, where the mutation is found outside the coding region |
| HLA-B*44:02:01:02S | An allele that encodes a protein which is expressed as a 'Secreted' molecule only |
| HLA-A*32:11Q | An allele which has a mutation that has previously been shown to have a significant effect on cell surface expression, but where this has not been confirmed and its expression remains 'Questionable' |
Table 1
Table 1 shows the definitions of HLA alleles at various levels of resolution. The HLA nomenclature described in Fig. 1 and Table 1 is reflected in the HLA reports that we deliver for each HLA sample and HLA sequencing run. If you’re in receipt of these reports you may want to refer to the HLA nomenclature described here.