['Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system which is widely believed to have a T-cell-mediated etiology. The cytotoxic T-lymphocyte antigen-4 (CTLA-4) antigen molecule plays a key role in the downregulation of T-cell responses. To examine the genetic association of the CTLA-4 gene locus with MS, we analyzed an exon 1 (A49G) transition.', 'One hundred and fifty-two MS patients and 154 controls were examined. The A/G transition was genotyped by a polymerase chain reaction followed by labeling with a SNaPshot kit and detection using a capillary genetic analyzer.', 'The genotype, allele and phenotype frequencies did not differ significantly between MS patients and controls. Those MS patients with AA and AG genotypes had 4.36 times greater risk of progressing from the relapsing-remitting to the secondary progressive form of the disease than those with the GG genotype.'] Is progression of multiple sclerosis associated with exon 1 CTLA-4 gene polymorphism?