THIS DEALS WITH GENETIC FACTORS
07/30/2007
MULTIPLE SCLEROSIS INFECTION
CRITERIA
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Research suggests the epigenetic code may explain why some disease skips generations and affects only one pair of identical twins.
The epigemetic markers as they are called can dramatically affect health but do not alter the DNA sequence. They influence the function of DNA and appear to play a critical role in growth, aging and cancers. The are suspected to be involved in diabetes, schizophrenia, bipolar disorder, obesity, heart disease, the immune system, especially autoimmune disease and multiple sclerosis is an autoimmune disease. Epigenectic markers are in constant flux and some can be passed to the next generation.
Data suggests that 70-80% of identical twins where one has MS the other does not develop MS (Ebers et al., 1986; Mumford et al., 1994). This compares with only 2% of affected fraternal twins both having MS (Ebers et al., 1986). It is suggested the epigenetic markers are involved. Some studies suggest only 3% of identical twins both have Ms where as another study suggests it is as high as 35%.
Fraternal twins, who do not inherit identical gene pools, have a lower rate for both siblings developing MS than identical twins, it may be that more than one gene is involved in MS susceptibility or epigenetic markers.
It is speculated that there is no one dominant gene that determines genetic susceptibility and that many genes, each with a small influence, are involved (Ebers, 1996). Multiple Sclerosis and juvenile diabetes may be different manifestations of the same disease. Research in Toronto and Pittsburgh suggest these diseases are one process. A wrong set of genes makes one predisposed to Ms another set to Diabetes. Recent research suggest it made be epigenetic markers that attach to DNA involved in the autoimmune diseases.
The data on identical twins also provide insight into the question of timing. Twins share essentially the same environment until they leave home (16-21). Thus, the fact that only 25% of identical twins both have MS, is good evidence for the interpretation that the environmental factor comes into play mainly after age 18. (Why do more develop MS after leaving home?). Some suggest epigenetic markers can be passed to the next generation and turned on/off with age.
A Vancouver study of 1,896 MS with 8,878 siblings suggest those who develop MS later in life their siblings have a lower percent chance of contracting MS than those who are Dx at age 20. They believe those of a younger age represent the genetically susceptibility factor. BUT please note these numbers are both under 5% risk.
Recently another very important epidemiological study was published by Ebers et al. (1995). These authors were able to demonstrate that children, who were raised in families in which non-blood relatives (step-Parents, step-brothers and sisters, adopted, etc.) had MS, had no increased risk of MS. This provided good evidence of the genetic factor in MS but more importantly demonstrated that MS is not transmitted by person to person contact. An earlier study which involved spouses of persons with MS also demonstrated this. If we don’t know the factors that cause the disease how can we jump to this conclusion?
MS is more common among Caucasians (particularly those of northern European ancestry) than other races, and is almost unheard of in some populations, such as Eskimos, Gypsis, Yakuts in Siberia and Bantu in Africa.
MS is rare among Blacks in Africa, the Black American rate is 50% of nonblack peoples.
In certain populations, a genetic marker has been linked to MS. A particular genetic trait occurs more frequently in people with MS than in those who do not have the disease.
MS is more often seen in the Caucasian population
The Lapps in Scandinavia appear to be immune to MS.
Native Americans and Hutterites very infrequently suffer from MS.
The Aboriginal of Australia appear to be immune to MS.
The Inuit of Canada appear to be immune to MS.
People of northern European descent, especially those of Scandinavian
heritage, may be genetically
predisposed to MS, many of whom settled in the northern United States.
The disease does appear to run in families. As many as 20 percent of
people with MS have at least one
affected relative. Compared to the general population, first-degree
relatives (children, siblings) of people with MS have a 20- to 40-fold
increase in risk of eventually having MS. However, it doesn't appear that
one gene is responsible for MS; rather, multiple genes likely contribute
to MS susceptibility.
Asian MS show a higher and more severe frequency of optic nerve involvement.
Cerebellar MRI lesions in Japanese are 6.4% vs. European/American patients of 50-90%
Research has identified two genetic variants that each raises a person's risk of developing MS by about 30%. (2007) One gene is interleukin-7 receptor (IL-7R), the other is (IL-2R) both affecting T-cell's. It is believed other genes and environmental factors are also involved.
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