MAJOR HISTOCOMPATIBILITY COMPLEX SUSCEPTIBILITY GENES FOR DERMATITIS-HERPETIFORMIS COMPARED WITH THOSE FOR GLUTEN-SENSITIVE ENTEROPATHY

Dermatitis herpetiformis (DH) shares some clinical features and major histocompatibility complex (MHC) markers with gluten-sensitive enterop athy (GSE). We compared MHC haplotypes in 27 patients with DH, 35 pati ents with GSE, and normal controls. As in GSE, the frequencies of two extended haplotypes, [HLA-B8, SC01, DR3] and [HLA-B44, FC31, DR7], wer e increased in patients with DH. Distributions of fragments of extende d haplotypes, consisting of some but not all of the elements of comple te extended haplotypes, were analyzed to attempt to localize a suscept ibility gene. Besides complete extended susceptibility haplotypes, (DR 3, DQ2) and (DR7, DQ2) fragments were most common in GSE. In contrast, DH showed only a few such fragments but many instances of the fragmen t (SC01). The differences in distribution of these fragments in the tw o diseases were highly significant (P <0.002). HLA-DQ2 and DR3 had the highest odds ratios for GSE, but the highest odds ratio for DH was fo r the complotype SC01. These findings suggest that the MHC susceptibil ity gene for DH is between class II and complotype regions, closest to the complotype, whereas that for GSE is in the class II region.