Although multiple sclerosis (MS) is less frequent in African Americans, it also tends to be a more severe disease in blacks by almost all measures; their disease tends to start a little earlier, their relapses are more severe with less recovery, their MRI scans show more widespread evidence of disease and injury at the same point in the disease course and they tend to become disabled more frequently and at an earlier age. The reason for this difference in MS severity between whites and blacks with MS is totally unknown but an area of active research. Most genetic association studies suggest that the genetic polymorphisms associated with MS severity in caucasians are similar to the haplotypes associated with MS severity in African Americans, although these polymorphisms explain only a minority of the reasons for MS severity in any group. Future research will likely define populations by genotype instead of phenotype (i.e. the color of your skin) to help answer these questions since it very difficult to determine genetic background by skin color alone. For instance, a large study in progress to investigate the genetics of MS in African Americans reported that genes of European ancestry ranged from 1 % to 71 % (median 19 %) in their study population.
Preliminary evidence suggests that African Americans may not respond as well to some MS treatments, although the studies are not conclusive. For instance, one study suggested a lower response rate to interferon treatments. Thankfully, another study suggested very good responses to Tysabri. My general approach to treating African Americans with MS is to monitor their response to treatment very closely and escalate to highly active treatments (Tysabri, Rituximab) earlier than in typical caucasian patients. Future determination of genetic/ethnic differences in response to therapy will require large community based research populations currently being assembled to answer these questions. Stay tuned for more information in the next year as research projects sponsored by the Accelerated Cure Project begin enrolling patients.
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