Further diversity at HLA-A and -B loci identified in Afro-Caribbean potential bone marrow donors

Two novel HLA-A and three novel HLA-B alleles were identified within a grou p of Afro-Caribbean individuals who were recruited as potential donors for the Anthony Nolan Bone Marrow Trust Register. HLA typing was performed on D NA extracted from peripheral blood mononuclear cells using sequence-specifi c oligonucleotide (SSO) probes for HLA-A and -B loci. Eight individuals ana lysed exhibited hybridisation patterns for which a type could not be assign ed. DNA from these individuals vias further typed by two methodologies: dir ect sequencing of PCR products and reference strand conformation analysis ( RSCA). The direct sequencing results allowed the identification of new alle les but did not allow confirmation of the cis/trans orientation of the new sequence motifs identified, RSCA analysis confirmed the results obtained by SSO and direct sequencing and in addition confirmed the cis/trans orientat ion of the new sequences One individual possesses a new A*30 allele - A*300 8 and two individuals possess an identical new A*74 allele - A*7404. The th ree novel HLA-B alleles were identified in three individuals: B*0812, B*155 4 and B*4503 respectively For the remaining two samples, A*2612 was identif ied. At present Caucasoid individuals, and therefore Caucasoid phenotypes, are predominantly represented on the various different volunteer bone marro w donor registries. The examples presented here highlight the potential for identification of further polymorphisms within the HLA system as more indi viduals from the much-needed ethnic minorities are recruited onto bone marr ow donor registers.