This article reviews the genetics of multiple sclerosis (MS), as well as intra-familial concordance and clinical correlations between different members of a family. Indeed, significant findings have been made on these topics in recent years.

The influence of specific genes on the clinical or radiological presentation of MS has been described as well as preliminary findings in the field of pharmacogenomics. Within familial forms of MS, correlations on specific aspects of the disease have been described, such as the age of onset or the clinical course between siblings.

The genetic contribution to the risk of developing MS is now estimated to be about 50%, with the genes involved mainly located within the major histocompatibility complex. Familial MS represents 12.6% of all MS cases, with the risk depending on the degree of genetic proximity to the index case. Furthermore, these familial cases seem to have a different clinical presentation from sporadic cases such as earlier worsening of disability and more severe long-term disability. Clinical correlations between different members of a family with MS have also been described, such as a similar age of onset between siblings, but deep clinical and radiological phenotyping is warranted to investigate MS disease severity concordance within familial cases of MS.