Tag Archives: genetics

Arthur Mourant: It’s All In the Blood

If being Jewish were in the blood, then what better way to find the markers of Jewishness then by studying blood itself? In his 1977 book The Genetics of the Jews, Arthur Mourant, one of the foremost cataloguers of blood groups during the 20th century, explained the advantages to this approach, “In popular anthropology since time immemorial…the visible and physically measurable body characteristics preceded the hereditary blood characteristics as the principal human taxonomic markers. Because of the precisely known mode of inheritance of blood characters, the latter have now superseded them… The hereditary diseases are, in general, too rare to be of value in studies of limited population samples…” So measuring blood groups is more precise than measuring heads and easier than identifying rare genetic diseases.

Mourant’s journey to Jewish population genetics was long. As an Oxford-trained geologist, he joined the Geological Survey of Great Britain during the 1920s to catalog the coal deposits in Lancashire. Unable to obtain an academic post in geology in Depression-era Britain, he returned to his native island of Jersey and set up a laboratory offering
medical tests. But running that laboratory was not satisfying, so in 1939, he entered St. Bartholomew’s Medical College in London. Upon his graduation with a medical degree in 1943, he became a Medical Officer in the National Blood Transfusion Service. The demand for blood products was great during the war and Mourant became a leader in the field.

After the war, he directed the UK Medical Research Council’s newly established Blood Group Reference Laboratory, the international standard for the World Health Organization.

A blood group is determined by the presence or absence of certain sugars, proteins, or fats on the surfaces of blood cells and other types of cells. Differences in blood groups limit the possibilities for blood transfusions — blood can be transfused only for a compatible type. Transfusions among individuals of noncompatible types result in transfusion reactions in which antibodies in the recipient’s blood break down the transfused red cells.

The presence of these antibodies was recognized first in 1901 by Karl Landsteiner, a Viennese pathologist. As he noted later in his Nobel Prize lecture of 1930, “My experiment consisted of causing the blood serum and erythrocytes (red blood cells) of different human subjects to react with one another. The result was only to some extent as expected. With many samples there was no perceptible alteration, in other words the result was exactly the same as if the blood cells had been mixed with their own serum, but frequently a phenomenon known as agglutination - in which the serum causes the cells of the alien individual to group into clusters – occurred.” Following Landsteiner’s lead, serum banks were created that collected serum from individuals of known blood groups and used these sera to test new individuals to determine their types. It was just such a laboratory that Mourant headed after the Second World War.

In the ABO system, there are four genetically encoded blood groups: A, B, AB, and O — O represents the absence of A or B. People with the O group are also known as “universal donors,” because they can give blood to anyone. The study of ABO blood groups made it immediately clear that there are different frequencies among different peoples. In Europe, the average frequency is 40 percent O, 40 percent A, 15 percent B, and 5 percent AB. In other populations, the balance changes.

Mourant was among the first to appreciate the utility of using blood groups as population genetic markers and the first to apply these to Jews. His catalog had varying data for the different blood groups and for other genetic marker systems (including G6PD). He concluded that the blood group data correlated with the known facts of Jewish history – although population geneticists at the time and today would agree that it is hard to draw major conclusions from a single genetic marker system.

The major Jewish communities were relatively homogeneous, yet distinct from one another. Each of the communities bore some resemblance to the local, non-Jewish population. In Mourant’s words, “Each major Jewish community as a whole bears some
resemblance to indigenous peoples of the region where it first developed.” Recent studies in Jewish population genetics have drawn upon analysis of the whole genome and have tended to confirm what Mourant observed – relative homogeneity within Jewish groups, distinctiveness between Jewish groups and some resemblance with local, non-Jewish populations. But Mourant was the first to study what was in the blood.

Posted on June 29, 2012

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Chaim Sheba

In Legacy: A Genetic History of the Jewish People, Harry Ostrer wrote about a series of scientists who contributed to our contemporary understanding of Jewishness. This week, he provides a series of short vignettes that describe their contributions about what it means to be a Jew.

jewish genesChaim Sheba, a surgeon general of the Israeli army and later the director general of the Israeli Ministry of Health, was also a colorful, pioneering Israeli geneticist. Early in his career, Sheba stumbled into human genetics in the process of preparing to practice medicine in his adopted country. Born in Austria, he left for Palestine with a “still wet” medical school diploma from the University of Vienna expecting to “dry the uninhabited swamps.” Drying the swamps was a way to eliminate malaria, a disease common not only in Palestine, but throughout the coastal Mediterranean basin. While on the boat to Palestine, Sheba read a book about tropical diseases and learned that one of the major complications of malaria was blackwater fever. Typically, the “black water” urine of individuals with red blood cells disrupted by malarial parasites contained the dark-colored breakdown products of the oxygen-carrying protein, hemoglobin.

When Sheba arrived in Palestine, he learned about an unexpected springtime occurrence of blackwater fever caused by eating fava beans, a popular Mediterranean delicacy. Favism had been known in ancient Greek times with Pythagoras, Diogenes and Plutarch all warning about the dangers of eating fava beans. Eating the beans or even smelling the pollen caused a sudden illness of abdominal pains and vomiting, followed by pallor, jaundice and brown-colored urine – all resulting from the rapid breakdown of red blood cells. During the 1930s, all of the patients that Sheba observed with favism were Jewish males of Iraqi, Yemenite, or Kurdish origin. During World War II, while serving as a surgeon in the British Army, Sheba observed men who experienced severe breakdown of red blood cells resulting from ingestion of the newly developed antibiotic and anti-malarial drugs. These reactions occurred primarily among Iraqi, Turkish, Greek, Yemenite, and Kurdish Jewish soldiers, and were also common among non-Jewish Greek and Cypriot soldiers, and Italian prisoners of war. To Sheba, it was striking that Ashkenazi Jews did not share these sensitivities that were prevalent among their co-religionists.

The reason for this difference between the Ashkenazi and other Jews became apparent after the war — an inability to repair damage to red blood cells that resulted from exposure to agents that were non-toxic to the majority of the population. This inability occurred in individuals who are deficient for the enzyme, glucose-6-phosphate dehydrogenase (G6PD). As its name would suggest, G6PD normally breaks down the sugar, glucose, and, in the process, generates an antioxidant that repairs red blood cells. Although G6PD is produced and used by all of the cells of the body, only red blood cells are sensitive to the effects of oxidizing agents. The enzyme is encoded by a gene on the X chromosome and men who carry a mutant gene on their single X chromosome are susceptible to these exposures. Women who have two copies of the X chromosome are relatively resistant to this condition when one of their X chromosomes carries a mutant G6PD gene.

Over time, Sheba recognized that other genetic diseases (Tay-Sachs, Gaucher, familial Mediterranean fever) were found almost exclusively within certain Jewish groups, reflecting the unique history of those groups. He assumed that these diseases were caused by transmission of a mutant gene that occurred sometime in the distant past, and then transmitted by a group of “founders” who migrated to that site of the Jewish Diaspora. This phenomenon has come to be known as a “founder effect.” Sheba was fond of using Biblical genealogies and spoke of conditions being transmitted by the descendents of the sons of Noah or other, later Biblical characters. Thus, Sheba established the notion that these diseases serve as genetic markers for the populations in which they occurred. Although not all of the members of the population carried these mutant genes, enough do to recognize a shared genetic legacy.

Posted on June 27, 2012

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Joseph Jacobs: Fighting Anti-Semitism, Genetically

In Legacy: A Genetic History of the Jewish People, Harry Ostrer wrote about a series of scientists who contributed to our contemporary understanding of Jewishness. This week, he provides a series of short vignettes that describe their contributions about what it means to be a Jew.

In the late 19th and early 20th centuries, Australian-English polymath Joseph Jacobs laid the framework for modern scholarship about all things Jewish, including Jewish population genetics. Born in Sydney, Australia, Jacobs went to England in 1872, intent on studying law at Cambridge University. Instead, he became interested in literature and anthropology, as well as mathematics, history and philosophy.

Upon graduating in 1876, he went to London to become a writer. While there, his professional development was transformed by two books. The first was George Eliot’s novel Daniel Deronda. Following publication, Eliot was derided by the English critics for turning an English gentleman into a Jew. She knew of the risk that she ran writing this novel, because she told Harriet Beecher Stowe that she wanted, “to rouse the imagination of [English] men and women to a vision of human claims in those races of their fellow men who differ from them in customs and beliefs.” Daniel’s self-discovery was life-changing not only for the character in the novel, but also for Jacobs. He wrote, “It is difficult for those who have not lived through it to understand the influence that George Elliot had upon those of us who came to our intellectual majority in the Seventies. George Elliot’s novels were regarded by us not so much as novels, but rather as applications of Darwinism to life
and art.”

The second transformative book was Francis Galton’s Hereditary Genius, a treatise in which the formulator of the concept of Nature versus Nurture observed that superior intelligence tended to be transmitted within families. Francis Galton, himself a famous polymath, was Charles Darwin’s cousin and Joseph Jacobs’ Darwinian mentor. Galton taught Jacobs that all human attributes could be measured – heads, heights, intelligence. Following this lead, Jacobs assessed Jewish accomplishment and wrote Jewish Genius. He applied Galton’s methods to measuring Jews and wrote Jewish Statistics: Social, Vital and
. Jacobs concluded that the low historical rates of intermarriage and proselytism and the physical resemblance among Jews favored the idea of a Jewish race. In his article in the Jewish Encyclopedia on ‘Anthropology’, he wrote, “The remarkable unity of resemblance among Jews, even in different climes, seems to imply a common descent.” When Mendel’s laws were rediscovered in 1901, Jacobs suggested that there was a genetic basis to Jewishness.

In 1906, Jacobs came to New York to edit the Jewish Encyclopedia, the major source of Jewish information at the turn of the last century. Jacobs felt that a study of Jewish history, when combined with an analysis of Jewish racial characteristics, would provide a powerful arsenal in the battle against anti-Semitism. He regarded it as his duty to fight anti-Semites of his day by pointing out Jewish contributions to civilization.

Posted on June 25, 2012

Note: The opinions expressed here are the personal views of the author. All comments on MyJewishLearning are moderated. Any comment that is offensive or inappropriate will be removed. Privacy Policy

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