Nomenclature for factors of the HLA system, update November 2006 *
The following sequences have been submitted to the Nomenclature Committee since the October 2006 nomenclature update and, following agreed policy, have been assigned official allele designations. Full details of all sequences will be published in a forthcoming report. Below are listed the newly assigned sequences (Table 1) and confirmations of previously reported sequences (Table 2). The accession number of each sequence is given and these can be used to retrieve the sequence files from either the EMBL, GenBank or DDBJ data libraries.
A new HLA-Cw*03 variant - Cw*031102.
A novel variant of HLA-Cw*0311, Cw*031102, possessing a silent substitution at codon 18 (GGA → GGG - conserved glycine) is described in this study.
A new HLA-B44 allele (B*44020102S) with a splicing mutation leading to a complete deletion of exon 5.
Using a combination of serology and polymerase chain reaction with sequence-specific primer (PCR-SSP), we have identified in a volunteer bone marrow donor a new HLA class I antigen within the B44 serotype. This human leukocyte antigen (HLA)-B44 variant was typed as 'blank' by microlymphocytotoxicity, whereas the B*44020101 allele was identified by PCR-SSP. A family study confirmed the Mendelian segregation of this blank antigen identified on one of the maternal haplotype transmitted to her child. The DNA sequence of B*44new, now referred to as B*44020102S, performed from the promoter region to the 3' untranslated region revealed a single nucleotide difference (A/G) compared to B*44020101 at the end of intron 4 in the acceptor-splicing site. This mutation leads to an incorrect splicing characterized by the deletion of exon 5 that encodes the transmembrane domain of the HLA antigen. Indeed, full-length complementary DNA sequencing revealed a complete absence of exon 5. Fluorescence-activated cell sorter analysis confirmed the absence of expression of HLA-B44 on the cell surface in the donor, compared to the HLA-B44 positive control. The isoelectric focusing analysis failed to reveal the presence of an HLA-B44 antigen in the donor, showing that no normal HLA-B*44020101 allele was synthesized. The new B*440201010102S allele is a soluble form of B44 without any detectable cell-surface expression. It can thus be considered as a soluble antigen, a form apparently inactive and unfit for antigen presentation.