MHC Nomenclature

New HLA genes, sequences, and quality control are determined by the WHO Nomenclature Committee for Factors of the HLA System (http://hla.alleles.org/nomenclature/committee.html)

The human nomenclature is exemplified by “HLA-A*02:101:01:02N,” in which the HLA prefix designates the species and the letter “A” the gene.
Following the * separator,

the first allele group is indicated here by “02”
the specific protein by “101.”
Synonymous DNA substitutions are shown by the third number (“01”)
differences in coding region by the final number.
Differences in level of expression are shown by the final letter—“N” is null, “L” is low, “S” for secreted molecules, and “Q” for questionable phenotype.
Since MHC-I (eg, HLA-A, HLA-B, and HLA-C) proteins consist of a polymorphic heavy (α) chain and a monomorphic light chain (β2 microglobulin [β2m]), it is sufficient to denote MHC-I molecules by the heavy chain nomenclature described above.