Genetics

This article reviews the current scientific understanding of how genetic factors contribute to multiple sclerosis, with particular emphasis on familial clustering, risk alleles, and genotype–phenotype correlations. It explains that MS is a complex, multifactorial disease in which genetic susceptibility accounts for approximately half of disease risk, while environmental influences account for the remainder. The review highlights the major role of the HLA region, especially the HLA-DRB1*15:01 allele, and discusses how genome-wide association studies have identified more than 200 genetic associations linked to MS susceptibility. It also examines familial MS, which represents about 12.6% of cases, and summarizes evidence that affected relatives may share similarities in age of onset, disease course, and clinical severity. Overall, the article emphasizes that although MS genetics has advanced considerably, further clinical and radiological studies are needed to clarify how inherited factors influence disease expression and long-term outcomes.