Immunogenetic aspects of nasopharyngeal carcinoma. IV. Increased risk in Chinese of nasopharyngeal carcinoma associated with a Chinese related HLA profile (A2, Singapore 2)

Abstract

In 1973 the authors described a specific genetic profile in terms of the HLA system as associated with an increased risk of nasopharyngeal carcinoma (NPC) in Chinese and consisting of an increased frequency of locus A antigen HLA A2 and a lack of detectable antigen(s) at locus B, i.e., a locus B 'blank'. The increased risk associated with the locus B blank was suggested to reflect the presence of (a) further HLA antigen(s) undetected by the antisera used (generally of Caucasian origin). In 1975 preliminary evidence was given both for the existence of a new locus B antigen, which was called Sin 2, and for the association of Sin 2 with NPC. Confirmation that the activity reported was a genuine locus B activity was provided by a study from California describing a new HLA activity, HS, detected with the serum from a Chinese woman. Exchange of sera showed that the anti sera used to define Sin 2 and HS were operationally identical. The present study of 110 Singapore Chinese with NPC and 91 controls confirmed the association between the occurrence of HLA antigen Singapore 2 (sin 2) and NPC in the Chinese population, and indicates that the increased risk for NPC is confined to the joint occurrence of Sin 2 and A2 antigens. These findings suggest that the genotype of importance in susceptibility to NPC is the A2 Sin 2 haplotype.