Significant Differences In MS Between African And Caucasian Americans, Study

Main Category: Multiple Sclerosis
Article Date: 24 Jan 2005 - 12:00 PDT

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A study, supported in part by the National MS Society, comparing the clinical characteristics of MS in African Americans and Caucasian Americans found significant differences between these two groups.

-- This study found that blacks with MS are more likely to experience a more aggressive course of disease, more likely to develop mobility impairments, and more likely to develop opticospinal MS and transverse myelitis.

-- Generally, the risk of MS in African Americans is around half that of Caucasian Americans, and is extremely rare in Africans. Such differences in epidemiology - who gets MS - may yield clues to the genetic underpinnings of this disease.

-- A prospective study - in which people would followed for a certain period of time - is being planned to validate and expand on these findings. This group and others also are using a new and powerful genetics technique known as "admixture mapping" to determine if differences in MS between African and Caucasian Americans stem from genetic factors.

Details: A study, supported in part by the National MS Society, comparing the clinical characteristics of MS in African Americans and Caucasian Americans found significant differences between these two groups. Bruce Cree, MD, PhD (University of California, San Francisco) and others found that African Americans tended to have a more aggressive course of disease, were at higher risk for developing mobility impairments, and were more likely to develop MS later in life, but were more quickly diagnosed. The study also found that blacks were at higher risk to have symptoms restricted to the optic nerve and spinal cord. The study, published in the December 14, 2004 issue of Neurology (63[11]:2039-45), was funded by a National MS Society research grant to Jorge Oksenberg, PhD, and a Society Sylvia Lawry Physician Fellowship to Dr. Cree.

Background: Generally, the risk of MS in African Americans is around half that of Caucasian Americans, and is extremely rare in Africans. Such differences in epidemiology - who gets MS - may yield clues to the genetic underpinnings of this disease. To investigate this possibility, the MS Genetics Group, a multicenter consortium, is collecting clinical information and DNA from African-American patients and their families and comparing them to those of Caucasian Americans.

In 2003, the group reported preliminary results of an effort to compare the clinical characteristics of this group with Caucasians at the American Academy of Neurology meeting (Abstract #P01.122). Now, the final report has been published, including more patients and further analysis.

The Study: The authors retrospectively reviewed the medical records of 375 African Americans with MS from 33 states, and 427 Caucasian Americans with MS from 37 states, recruited for genetics research by the MS Genetics Group. The proportion of women to men, and the mix of clinical types of MS were similar between these groups.

Among those studied, blacks tended to have a more aggressive course, with symptoms progressing to EDSS 6 (a score indicating need of a cane to walk) or higher in 16 years (median) versus 22 years for whites. The age at onset was about 2.5 years later in blacks than in whites, yet blacks tended to be diagnosed more quickly (median of 1 year after onset versus 2 years). Also, blacks tended to present with symptoms in more than one site (e.g., brain, spinal cord). Opticospinal MS - where the disease is restricted to the optic nerve and spinal cord - occurred in 16.8% of blacks compared with 7.9% of whites. African Americans were also at higher risk for transverse myelitis, an acute attack in which the spinal cord loses its ability to transmit nerve impulses up and down.

African Americans were at higher risk for requiring a cane to ambulate. There was a trend - although this did not reach statistical significance - suggesting that blacks were at greater risk for becoming dependent on a wheelchair. Further analysis showed that this is in part due to the older age at onset, and may also be due to the higher incidence of transverse myelitis, which can cause paralysis and numbness in the legs and trunk below the level of the inflammation.

Analysis of access to care and disease-modifying therapies indicated no significant delay from onset of symptoms to diagnosis in either group, and that the groups were equally likely to receive disease-modifying treatments for MS.

Conclusion: This study found that blacks with MS are more likely to experience a more aggressive course of disease, more likely to develop mobility impairments, and more likely to develop opticospinal MS and transverse myelitis. The authors note that as this study was a retrospective review of medical records, it did not evaluate aspects such as environmental or socioeconomic factors that might affect the results. A prospective study - in which people would be followed for a certain period of time - is being planned to validate and expand on these findings. This group and other Society-supported scientists also are using a new and powerful genetics technique known as "admixture mapping" to determine if differences in MS between African and Caucasian Americans stem from genetic factors.

-- Research Programs Department (The National Multiple Sclerosis Society)
The National Multiple Sclerosis Society

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