Genetic and environmental factors in multiple sclerosis

Introduction. Multiple sclerosis is expressed in genetically susceptible persons randomly affected by an unknown environmental factor, probably a virus, which sets off an abnormal immune process. Development and conclusion. Race is an important predictive risk factor for multiple sclerosis, but genetics alone do not explain the occurrence of this disease. The genetic predisposition is complex, since several loci are involved in the susceptibility. Probably the immune process seen in multiple sclerosis is a consequence not a cause. The cause is possibly unique and due to infection. The causative agent may be rare or on the contrary may be frequent, but has different biological effects on susceptible persons. Epidemiology alone is not sufficient to find the cause. This requires collaboration from the basic sciences (genetics, microbiology, etc.). The results of epidemiological methods would be much improved if a biological marker for the disease was available.