Although most people diagnosed with MS are aged between 20 and 50, children can also develop MS. This is very rare, and scientists are still trying to understand the causes and characteristics of childhood MS.
If the onset of MS in childhood reflects a heightened risk for MS, then it follows that these children and their families may have a greater genetic susceptibility to the disease. However, in our recent international study of MS in children, only 11 percent of the affected children reported a family history of MS. This may be because the family members of children with MS may develop the disease themselves in the future. Therefore long-term family studies are required before we can fully evaluate the risk of occurrence of MS in relatives of children with MS.
Little is known about the frequency of childhoodonset MS occurring in families in which a parent also has MS. Similarly, few studies have specifically explored the genetic aspects of childhood MS. In a Russian study, children with MS had an increased frequency of a specific genetic feature (the HLA-DR2 (15) phenotype) as compared to their siblings, parents, and healthy peers. Other genetic studies have been performed in an attempt to find a specific gene defect in childhood MS, but studies looking for defects have failed to find any abnormalities. A study searching for mutations in the Leber’s Hereditary Optic Neuropathy genes in children with MS that affects the optic nerves identified several common variations, but no actual disease-causing genetic errors.
Studies involving groups of more than 20,000 adults with MS have, to date, consistently identified only the HLA as a diseasesusceptibility marker. Given the relative rarity of MS in children, it is unlikely that even collaborative studies will provide sufficient numbers of participants for similar studies to be done in childhood MS. More detailed genetic analysis of childhood MS will await identification of specific genes in adult MS which can then be extended to genetic studies in childhood-onset disease.
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