MS study launched

SORIYA DANIELS

Israeli Jews and Arabs are at the centre of a study being conducted by a Pennsylvania medical researcher seeking factors that lead to the onset of multiple sclerosis, a disease of the central nervous system that causes a wide range of neurological dysfunction affecting walking, speech, vision and nerve sensations.

What is most intriguing is that not only does MS occur with uneven geographic distribution around the world, it can also appear with different incidence rates in people of different ethnic origins living in the same region. In Israel, multiple sclerosis occurs three times as frequently among Jews of European descent as it does among Arabs or even Jews immigrating from North Africa or Asia. One generation later, however, the offspring of the Jewish parents of Sephardi descent show rising rates of multiple sclerosis, becoming almost comparable to Israeli Jews of European descent. Dr. Milton Alter of Lankenau's Institute for Medical Research wants to know why.

Alter and his colleagues are approaching this question by focusing on risk factors faced by these three populations. They have completed a population study confirming previous findings that Arabs in Israel have a lower risk of developing MS than Jews born in Israel. "In such a small region," said Alter, "that is atypical."

"Jews living in Israel begin to show the higher rates of the Europeans within one generation," said Alter. "That points us towards environmental factors, because you couldn't change the genetics of an entire population within one generation."

Alter noted that living a more advanced, European-Israeli lifestyle seems to increase the risk of MS and conversely, the Arab lifestyle seems to protect against the disease. What could that protective factor be?

"The age at which one acquires childhood infections may influence the risk of autoimmune diseases like MS," said Alter. "Early exposure may be protective against autoimmune diseases. In places where children acquire childhood diseases before age five, they may be protected against autoimmune diseases, including juvenile diabetes, asthma and MS.

"In populations where infection is delayed, those children might be at a higher risk of developing an autoimmune disease, whereby the body's white blood cells attack healthy cells." Alter added that one would expect younger siblings in a family to have a lesser incidence of MS because they would be exposed to infections from older siblings.

Further study is required to determine which infections could give the protective benefit. "It's not one exposure," said Alter. "It is cumulative factors plus a genetic predisposition."

Israel appears to be a fertile ground for this study, not only because of its multi-ethnic population, but a data set collected on more than 92,000 Israeli infants born in 1967 and followed since. Of this population, Alter predicts that there will be more than 60 people who suffer from MS. He will trace childhood infections, age of immigration to Israel, ethnic background, father's occupation, sociocultural differences and the number of siblings and their order in the family, as well as economic conditions, to tease out factors that may cause or protect against MS.

Soriya Daniels is a freelance writer in Florida.

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