The progressive and eventually fatal neurological disorder of Parkinson’s disease is significantly lower among the Druse than in other populations in Israel, according to a new study by the University of Haifa and the Rambam and Carmel Medical Centers, both in Haifa.

Not only was the prevalence of PD lower among the Druse – even though they have tended to inbreed and marry first cousins over the generations, and thus risked higher genetic disease rates – but they also suffer less from essential tremor (ET), another neurological disorder.

The study was initiated by Dr. Rafik Ibrahaim of the university’s Safra Brain Research Center and carried out with Prof. Yehudit Aharon-Peretz and Dr. Jamal Hasson of Rambam Medical Center and Dr.

Samih Badarna of Carmel Medical Center. The research was funded by the Science and Technology Ministry.

The researchers, in looking at PD and ET rates among the Druse, stated that this ethnic group is a “genetic nature reserve” because they have lived in the same geographical region for over 1,000 years and do not marry outsiders.

Statistics on the world population showed that ET affects an average four percent of the population over 40 and PD an average of 1.5%. Ethnic differences cause variations. For example, in the US, among Caucasians the rate of ET is 1.7 times that in African-Americans, while the rate is 1.2 times higher in Hispanics than among the blacks.

Over 9,000 Druse aged 51 and above who live in villages in the Galilee took part in the study by completing questionnaires about their health.

Blood samples were taken from those who answered that they suffer from tremors of any kind.

Only 27 Druse said they had full tremors. The rate was thus 1.49%. Just nine Druse said they had PD, making the rate just 1.13%.

Thus the results, the researchers said, were surprising at first, because they expected consanguinity (inbreeding by first cousins) would make them much more liable to get PD and ET.

However, the researchers were less surprised when they looked at the previous genetic survey of Israeli Druse carried out by Prof. Karl Skorecki of Rambam Medical Center, who discovered that genetically, more than 150 different genealogical lines made up the community. This is a relatively large amount, despite the fact that the Druse are a small population and limited to a specific geographical area.

This suggests that having so many different genealogical lines when the community was originally formed prevented the increase in genetic diseases.

“The current research together with previous findings strengthen the principles of faith and tradition of the Druse that they represent offspring of many races that reached this area when the religion was founded and they joined the community more than 1,000 years ago,” Ibrahim said.

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