MS is a multifactorial disorder caused by an interaction between environmental factors and genetic predisposition. The chromosomal region comprising the major hiostocompatibility complex (MHC) contains one or several genes that contribute from 20 to 50 percent predisposition to MS. No other significant predisposing genes are known but if present, are they likely to predispose less significantly than MHC.

Large DNA collections, high output genotyping facilities, precise knowledge of the human genome and adequate statistical methods should allow identification of further MS predisposition genes in the future.

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