Association of a CA repeat polymorphism upstream of the Fas ligand gene with multiple sclerosis

We have analyzed a CA repeat polymorphism localized 46-kb upstream of the F as ligand gene in Spanish and American populations that include 139 healthy controls and a cohort of 177 unrelated relapsing and remitting multiple sc lerosis (MS) patients. The MS patients consisted of two groups. one with a family history of MS and one without. The frequency of the 13 CA repeats (a llele B) was lower (p = 0.01) in MS patients than in controls. 0.45 and 0.5 5 respectively. The odds ratio (BB vs. AB/AA) for MS patients vs. healthy c ontrols was 0.51 (95% CI 0.3-0.9: p = 0.01). The odds ratio (BB vs. AB/AA) for MS patients extracted from multiply affected families vs. healthy contr ols was 0.22 (95% CI 0.07-0.62: p = 0.002). The HLA DRB1* 1501-DQB1* 0602 h aplotype is associated with B allele with a relative frequency higher than A allele (0.52 and 0.48 in patients vs. 0.68 and 0.32 in controls). The res ults suggest that chromosomes with B allele have a genetic background that reduces susceptibility to MS, particularly in the familial forms. (C) 2001 Elsevier Science B.V. All rights reserved.