The immunogenetic background of scleroderma--an overview.

Currently it may be stated that the MHC associations in scleroderma support the classification of disease subsets, but in no ethnic group is the overall association strong enough for clinical use. In different ethnic groups, the distribution of MHC alleles varies, as does the degree of linkage disequilibrium between alleles of the linked loci. This concept is even relevant to relatively close populations. Thus Whiteside noticed that, if those patients referred from more than 100 miles from the study centre were excluded, then the strength of the DR1 association increased. The environmental contribution to scleroderma is unknown, except in the case of toxin or solvent associated disease. Different causal environmental agents found in different global regions might result in separate MHC associations and hence explain the discrepancies noted above. There are indications that associations between specific subsets of SSc patients and genetic markers will assume greater importance both diagnostically and prognostically. The lung fibrosis group look prime candidates, for example. Genetic markers are also a useful means of relating chemically-induced SSc-like disorders to the classical disease. Vinyl chloride disease provides an example. There is much heterogeneity within the disease, in terms of extent of skin involvement, severity, and of organ involvement. It is clear that the different clinical subsets of scleroderma are characterized by different associated MHC alleles. There are also many cases of clinical overlap with related diseases, and certain of these diseases have a different HLA association, which could detract from the primary HLA type associated with SSc.(ABSTRACT TRUNCATED AT 250 WORDS)