Ligers et al. have explored whether there was an association between a genetic susceptibility to MS and three intragenic polymorphisms of the CTLA-4 gene, a C/T base exchange in the promoter (p.-318), an A/G substitution in exon 1 (p.49), and a dinucleotide repeat polymorphism in exon 4 (p.642) [117]. The gene discussed is CTLA4; the disease is myeloid sarcoma.