The Mafa-B alleles have been named according to published nomenclature proposals (Klein et al. 1990; Ellis et al. 2006) ; however, the number of Mafa-B lineages has exceeded 100, and for the lineage numbers three digits have been introduced. In this document, the designations that were published previously are extended with a zero, and contain five ciphers. Two alleles that are highly similar receive the same lineage number, but any difference is indicated by the allele number (fourth and fifth cipher). If two alleles have synonymous base-pair differences, they receive an identical allele number, and the difference is indicated by a sixth and seventh digit. For example, Mafa-B*0950101 has synonymous differences in comparison to Mafa-B*0950102 and non-synonymous ones as compared to Mafa-B*09502. The novel alleles were submitted to the EMBL-EBI database (accession numbers FM212793-FM212843, FM246485-FM246500, FN423784, FN546179, and FN546180) and to the Non-human primate section of the IMGT/MHC Immuno Polymorphism Database (Robinson et al. 2003) .