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28.07.02, 20:39
dajcie spokoj, to sa chorzy ludzie i nie trzeba ich dobijac, maja dosc
genetycznych chorob
Geneticists study Jewish genes for disease clues
By Megan Goldin
JERUSALEM (Reuters) - Genetic sleuths in Israel are collecting thousands of
blood samples from Jews of European origin in a race to uncover the genetic
causes of diseases such as schizophrenia, asthma and Parkinson's disease.
IDgene Pharmaceuticals is so far the only company in Israel with government
approval to study the genetic make-up of Ashkenazi Jews in the hope it could
help them hone in on the genetic causes of common diseases.
The relatively uniform genes of Ashkenazi Jews are a boon for geneticists who
must sift through three billion human DNA sequences and around 40,000 genes
in their search for the genetic causes of common and often deadly diseases.
"The population of Ashkenazi Jews is relatively homogenous which facilitates
gene discovery," said Ariel Darvasi, IDgene's president and a geneticist at
Jerusalem's Hebrew University.
Darvasi said the genes that cause diseases are easier to track in a
homogenous population because there are less genetic differences in their DNA.
"The homogeneity reduces the genetic noise and the signal comes out more
clearly," said Darvasi.
His company has collected 10,000 blood samples from Ashkenazi Jews in Israel
suffering from eight diseases: asthma, type 2 diabetes, schizophrenia,
Parkinson's disease, Alzheimer's disease, breast cancer and colon cancer.
IDgene plans to study the genetic links for some 20 to 30 common diseases
prevalent in some one percent of the population.
The genetic profiles of the anonymous Ashkenazi donors in each disease
category are being compared to the genetic profiles of a control group of
Ashkenazi Jews not suffering from the disease. All the donors have signed
consent forms.
By searching for genes that frequently appear among sufferers of a disease,
but do not show up among those without the ailment, geneticists can more
easily find the genetic needle in the human genome haystack.
ASHKENAZI JEWS
The forefathers of the Ashkenazi community began to settle in parts of Europe
during the Roman Empire, particularly after the Romans conquered Jerusalem in
AD 70. Ashkenazis now make up more than 80 percent of world Jewry.
They moved to Spain, France, Italy and other Mediterranean basin countries,
but spread over the centuries to the Rhineland in Germany, Poland and Russia.
Frequent persecution kept their numbers small.
Modern Ashkenazi Jews are believed to descend from about 1,500 Jewish
families dating back to the 14th century. But Darvasi said the forefathers of
today's Ashkenazis came from an even smaller gene pool.
Darvasi said "maybe 500 families were really the source of the total
(Ashkenazi) population today...probably in the order of 100 independent
chromosomes", because they enjoyed better nutrition and had lower infant
mortality rates than less affluent Jews.
In the 18th century, Ashkenazi Jews began to flourish and their numbers
swelled to around 10 million today.
For religious and historical reasons, most Ashkenazi Jews married within
their community, a phenomena that Darvasi said shows up in the Ashkenazi
genes he studies which tend to have a high degree of similarity.
HOMOGENOUS GENE POOLS
Darvasi said the 2.8 million Ashkenazi Jews in Israel provide a very large
homogenous gene pool for researchers.
But there are non-Jewish groups, including Sardinians and French Canadians,
who have similar potential in that they too are a relatively large pool of
homogenous people to study, he said.
Iceland's deCODE genetics Inc has a head start over IDgene which began work
two years ago.
DeCODE has already reported finding 350 genes linked to more than 40 common
diseases.
Reykjavik-based deCODE is sorting through the medical records of Iceland's
population of around 300,000 people which it says has changed little in
genetic make-up since the Vikings arrived in the ninth and 10th centuries.
But Darvasi said geneticists disagree over the degree of homogeneity of
Iceland's population, which according to some studies also includes people of
Norwegian and Celtic descent.
In January, IDgene announced a $7.65 million second investment round by
venture capitalists Apax Partners and IsraelSeed Partners and the British-
based Wellcome Trust, one of the world's leading financiers of genetic
research.
Darvasi said it will take researchers years to isolate the genes responsible
for various diseases. But once they do, it will be possible to start
developing drugs designed to treat the specific biological causes of the
disease.
"Each gene encodes a protein...Once you identify it you can look at the
chemical pathway it invokes," he said. "We try through genetics to understand
the biology of the disease and treat the disease with that knowledge."
He said he is not concerned about the competition from Iceland and other
companies studying other homogenous genetic groups.
"Most of this field is unknown so chances are that each of us will get
something out of our research," Darvasi said.
