Convention for HLA allele naming. The figure illustrates the meaning of each component of an HLA allele name. Fields 3 and 4 may not be used in a name if no synonymous DNA substitutions or differences in a noncoding region are found for a particular allele. For example, based on the IMGT/HLA database Version 3.1.0, July 2010,²  A*02:07 has not been found to have synonymous DNA substitutions or differences in the noncoding region; thus, fields 3 and 4 have not been assigned for this allele. Courtesy of Prof Steven Marsh, Anthony Nolan Research Institute, London, United Kingdom (www.hla.alleles.org).