**2. Immune response-related genetic factors in the risk and progression of multiple sclerosis**

MS is a typical gender-dependent disease; a higher risk of MS is observed in women than in men in all populations and races. A study conducted in Canada found female to male ratio in individuals affected by MS to be 3:1 [11]. The risk of MS development in siblings of an affected individual is estimated to be 5%, in children 2%, in monozygotic twins 25% [5]. However, it has been shown that genetic predisposition is not strong enough to induce disease develop‐ ment, and appropriate environmental triggers are necessary to start the disease process [1, 12]. In general, the MS-associated genes can be classified into genes of the HLA-complex and*non-HLA* genes [3].
