Identification of a novel HLA-B allele (B*4202) in a Saudi Arabian family with Behçet's disease.

A new HLA-B antigen, tentatively called HLA-B42AND, was identified as a B42 serologic variant in a Saudi Arabian family. DNA sequencing analysis of the second and third exon of this new B allele revealed that B42AND was identical to B*4201 except for a single T to C substitution at position 97 of exon 2. This substitution results in histidine (CAC) at codon 9 in B42AND instead of tyrosine (TAC) in B*4201. The antigen frequency of B42AND in a Saudi Arabian population was around 10%. This novel B42AND has officially been named HLA-B*4202.