Multiple sclerosis and HLA class II susceptibility and resistance genes

Abstract

Abstract Probes to the HLA class II genes DRβ, DQβ, and DQα were used to study DNA from unrelated Caucasian multiple sclerosis (MS) patients by sequential restriction fragment length polymorphism (RFLP) analysis in Taq1 restriction enzyme digests. Comparison of 104 patients and 108 controls, who were not matched for DR type, has identified for the first time a linked series of allele‐specific RFLPs or allogenotypes which form an extended haplotype that is preferentially associated with MS. These allogenotypes include DRw15 or DR2(15);DQβlb, which corresponds at the DNA level to the DQwl (DQw6) serotype; a DQA1 allogenotype termed DQα1b; and a 2.2kb DX (DQA2) allogenotype termed DXαU (DQA2U). The role of HLA class II genes in susceptibility to MS was found to be complex. First, 23 of 104 MS patients showed DR‐DQ linkages which were not observed in our control population. We suggest these anomalous associations may be important in the pathogenesis of MS. Second, homozygosity of a 2.0 KB DX (DQA2) gene, termed DXαL (DQA2L), Showed a strong negative association with MS. DXαL (DQA2L) is in strong linkage disequilobrium with DR1, 5(w11)7, and a subset of DR4, all of which also showed a negative association with MS, Since DXαL (DQA2L) does not code for any known product, DR1, 5(11), 4, and 7 become candidates for disease resistance genes. Third, in EcoR1 and EcoRV digests of DNA from both controls and patients homozygous for DQβ1b a number of different RFLP patterns were identified and these RFLPs patterns were identified and these RFLPs were associated with either relapsing‐remitting or progressive MS. This suggests there may be HLA sequence differences between individuals bearing a particular class II allele and these may correlate with the clinical course of MS.