MS is not a hereditary disease, in the sense that parents ‘pass on’ the illness through their genes. However, there may be a hereditary ‘receptivity’ to MS, with the disease often occurring in members of the same family. Evidence suggests that this occurs more frequently than can be put down to mere coincidence1.
Although this indicates a genetic linkage, it is worth remembering that most family members share a similar environment and lifestyle, and this may also contribute to the causes of the disease. That said, the risk of children and brothers and sisters of someone with MS developing the disease is still very low, with a 96 – 98% probability that a direct relation will not be affected by MS.
Many people with MS are naturally concerned about the chances of the disease being experienced by other family members and children. Unfortunately genetic counselling and genetic screening are difficult to provide due to the lack of definitive knowledge regarding the genetic control of the disease. However, if you have MS, it is important to be aware that the risk for first-degree relatives of people with MS is greater than the risk to second-degree relatives. The risk of family members of an MS sufferer developing has been studied and is reportedly2:
- 4.4% for a sister;
- 3.2% for a brother;
- 2.1% for a parent; and
- 1.8% for a child – if both parents have MS this risk increases to approximately 20%.
MS and studies of twins
A number of studies examining the incidence of MS among twins add further evidence for the lack of a direct genetic link in MS. If genes were solely responsible for the development of the disease, then the presence of MS in one monozygotic (identical) twin would produce a 100% risk for development in the other twin. However, a study performed in Canada has revealed that the risk among monozygotic twins is approximately 30%3. Additionally, dizygotic (non-identical) twins, the risk of occurrence in the second twin is approximately the same as for non-twin siblings, being 4.7%.
Recent studies
In 2005, researchers at the Serono Genetics Institute (SGI) achieved a major milestone in identifying and creating a register of genes involved in Multiple Sclerosis (MS). For the first time in this disease area, researchers identified 80 genes involved in the inflammatory and neuro-degenerative pathways of MS, based on a 40% genome scan comparing the genetic profile of a total of 1,800 people with MS and healthy individuals in different populations. Knowledge of genetics in MS may provide a basis for designing safer and more effective drugs, enabling physicians in the future, to address unmet needs and potentially better match treatments to the individual patient.
1. Ebers and Sadovnick, 1994; The role of genetic factors in Multiple Sclerosis susceptibility. J Neuroimmunol 1994; 54: 1―17., Robertson et al., 1996, Age-adjusted recurrence risks for relatives of patients with Multiple Sclerosis. Brain 1996; 119: 449―55.
2. Robertson et al., 1996, Age-adjusted recurrence risks for relatives of patients with Multiple Sclerosis. Brain 1996; 119: 449―55.
3. Sadovnick et al. 1993, The geographic distribution of Multiple Sclerosis: a review. Neuroepidemiology 1993; 12: 1–5.
