Is MS Hereditary?

Genetic factors are recognized as playing a role in MS. This is not to say that they cause MS. Although MS is typically a disease of people of European ancestry, it also occurs in African Americans, who share genes common in both African and European populations. The observation that MS is about one half as common in African Americans as white Americans would seem to correlate with a risk related to European ancestry. Among Europeans, MS is much more common in northwestern Europe, particularly in Scandinavia, Scotland, and Ireland. However, as physicians trained in neurology returned to areas in southern Europe that were considered to be low-risk areas, such as Sardinia and Sicily, MS became diagnosed much more often. Indeed, these two areas are now considered to be high-risk areas. These observations have been interpreted to suggest that hereditary factors as well as environmental factors are involved in the risk of MS.

Certain specific genes are more common in MS patient populations. Each of the genes HLA-A3, HLA-B7, and DR-2 (now often referred to DR-1 1501b), which are all located on chromosome six, are each twice as common in MS as compared with the general population. However, the majority of persons in those populations with these genes do not have MS, clearly indicating that they are not “MS genes.” Ten years ago, the DR gene was proven to be an immune response gene. DR-2 is simply a genetic mutation of the immune response gene that is twice as common in the MS population as compared with the general population. DR-2 is now more correctly identified as DR-1 1501b. It is possible that certain mutations of immune response genes are more efficient in their function in turning on immune responses, as least as far as reactions to nervous system proteins. MS is not a simple hereditary disease, but it does appear more commonly in families of MS patients.

Karen’s comment:

My two sisters and I are often mistaken for triplets. We have statistically the least likely genetic composition that could result from our parents. Our tall, dark brown-eyed, brunette mother often called the three of us short, blue-eyed, blond daughters her “recessives!” My youngest sister has two daughters who also resemble us. There is a lot of immune-based illness in our family, including diabetes and allergy.

When one sister had a ringing in her ear and migraines and a niece had unexplained falls, we held our collective breath until MS was ruled out for each of them. So far, I am the only one in my family who has been diagnosed with MS; however, I qualify this with “so far,” as it is a concern that we cannot ignore.