“…The results of phenotype–genotype analyses in Slovak MS patients showed no evidence for association between rs1800693 and the age of disease onset, MS severity or progression, which is consistent with most other studies performed in patients of predominantly European origin (Baranzini et al, ; Brynedal et al, ; Comabella et al, ; George et al, ; IMSGC et al, ; IMSGC, ; Lin et al, ; Ottoboni et al, ; Pan et al, ). However, possible effect of rs1800693 on disease course cannot be fully excluded yet, as suggested by a recent study in Russians which reported an association of C allele with moderate‐to‐severe MS (MSSS > 3) and unfavourable variants of MS manifestation, such as motor disorders, brainstem disorders, impaired coordination, pelvic disorders, mental disorders or polysymptomatic onset (Kulakova et al, ). By contrast, a study in African Americans reported opposite effect of rs1800693 on MS severity, with the C allele being associated with reduced MSSS (Johnson et al, ).…”