The analysis of the genetic sequence of Y chromosomes showed that the Jewish men who carry the tradition of belonging to the priesthood probably had a common ancestor who lived 2,000 or 3,000 years ago
Is there a doctor in the lab? Guest of the section: Prof. Karl Skortsky, Rambam Medical Center and the Technion "The Weizmann Institute of Science does a huge service to medicine in Israel by bringing the doctors to the laboratories and teaching them to think like scientists"
Are certain Jewish men related by family ties to the biblical Aaron? Are millions of Ashkenazi Jews the offspring of a small number of "founding mothers"? Do all cancer metastases arise from the same primary tumor? These are some of the questions asked in the research of Prof. Karl Skortsky, a doctor from the Rambam Medical Center, and head of the Rappaport Research Institute at the Technion, who recently worked, as part of a sabbatical year, in the Department of Computer Science and Applied Mathematics of the Weizmann Institute of Science.
How does a doctor fit into a group of computer scientists? Prof. Skortsky divides his time between treating patients at the Rambam Medical Center and researching population genetics. He believes that regular communication and collaborations with computer scientists can help achieve unconventional solutions - "outside the box" - to research questions in the fields of life sciences. He came to the institute after reading about the research of Prof. Ehud Shapira from the Department of Computer Science and Applied Mathematics and the Department of Biological Chemistry, who developed an innovative computational approach to examining biological issues. In fact, Prof. Skortsky was already on sabbatical at the Weizmann Institute in 1991 (see frame). "The Weizmann Institute is an excellent place, which surpasses many places in the world in terms of the research environment and research support," he says.
Prof. Shapira developed an approach that combines advanced biochemistry with computational methods, and utilizes certain markers in the DNA molecule to find out the origin of body cells. This is especially the DNA parts called microsatellites, which include genetic "letters" that repeat themselves, and therefore tend to accumulate errors every time the cell divides. So, for example, it is easy to make a mistake in the word "Mississippi" and write it as "Mississippi". By analyzing genetic errors of this type, the scientists can tell how many times the cell has divided in the past and what the relationship between the cells is.
During his sabbatical, in joint research with Dr. Shalu Itzkovits, a post-doctoral researcher from Prof. Shapira's laboratory, Prof. Skortsky focused on the study of cancer cells. For example, determining how many times leukemia cells have divided may allow scientists to assess how aggressive the leukemia is. Additional studies, which are based on microsatellites in DNA, can help determine when cancerous metastases formed from a certain tumor, and from how many cells in the original tumor they developed.
"These studies," says Prof. Skortsky, "are similar to studies in population genetics that I carried out for many years at the Technion. You check the proximity between cells instead of people, but in both cases you use DNA analysis to build genealogies that reveal common ancestry and the different 'family' branches." his research
At the Technion he focused on the origins of different population groups. In one study he studied the Y chromosomes which determine the male sex and are passed unchanged from father to son - therefore they serve as an important tool for tracing roots. The research revealed that modern Jewish men, presumed descendants of priestly families, probably had a common ancestor who lived 2,000 or 3,000 years ago - a finding that apparently confirms the Jewish tradition that the Jewish priests are the descendants of Aaron, the brother of Moses. In another study, Prof. Skortsky and his research partners found that almost half of the Ashkenazi Jews have genetic roots that go back to a small group of four women who lived about two thousand years ago. Another finding: the Druze populations living in the north of the country and in the neighboring countries are genetically very diverse, which confirms the Druze tradition, according to which the origin of the tribe is rooted in many roots.
In the future, Prof. Skortsky may collaborate with Prof. Shapira's laboratory on medical issues not related to cancer, such as regeneration of the kidney after injury. Prof. Shapira says that Prof. Skortsky's deep knowledge of biology and medicine helped the institute's scientists to think about new clinical applications and develop connections in the medical community in Israel and around the world.
Prof. Skortsky: "The Weizmann Institute of Science does a huge service to medicine in Israel by bringing the doctors to the laboratories and teaching them to think like scientists. The more knowledgeable doctors are in scientific thinking, the better they will be able to treat patients. Modesty is an important quality for every person, and especially for a doctor. When you work with scientists, you realize how much you don't know, how much we all must recognize the limitations of our knowledge and always strive to know more."
Prof. Skortsky arrived in Israel and the Weizmann Institute two weeks before Iraqi Scud missiles began to fall on Israel, in early 1991. He studied medicine at the University of Toronto and Harvard, worked at the University of Toronto, and came to the Weizmann Institute to work with Prof. David Gavol and Prof. Yossi Yordan, who were known as experts In the study of growth factors. He then considered immigrating to Israel, and wanted to make sure that it was possible to engage in high-level research in Israel. "The stay at the institute had a decisive influence on our decision to immigrate to Israel," he says. When the first Scuds began to hit the cities of Israel, he received a phone call from his parents (who have since passed away). The parents, both Holocaust survivors, did not ask their only son to return to Canada. Instead they boarded the plane and joined their son's family in Rehovot, in the sealed room. "We decided that if we got through it, we could live in Israel," he recalled. Since he wanted to engage in both scientific research and patient care, he chose to join the medical staff of the Rambam Medical Center. There he managed the kidney department for a decade. He currently serves as the director of medical and research development at the center.
The question: Is it possible to provide scientific proof for the hypothesis that certain Jewish men are descendants of priestly families?
The findings: The analysis of the genetic sequence of Y chromosomes showed that the Jewish men who carry the tradition of belonging to the priesthood probably had a common ancestor who lived 2,000 or 3,000 years ago.