Crohn's disease has been found to be quite prevalent among a specific Jewish population from Eastern Europe known as the Ashkenazim. The Ashkenazim now live all over the world, but they largely lived in Europe for centuries, according to the Jewish Virtual Library, a division of the American-Israeli Cooperative Enterprise.
The Hebrew University of Jerusalem states that Jews whose ancestors would become the Ashkenazim may have been moving into Europe during the time of the Roman Empire. Over the years, the Ashkenazim have been a largely insular people, tending not to marry outside of their own ranks. This has created a genetic makeup that is uniquely Ashkenazim and has also led to a higher occurrence of many diseases caused in whole or in part by genetic factors. These include: Tay-Sachs, Gaucher disease, Bloom syndrome, Idiopathic torsion dystonia, and familial dysautonomia, the university states.
The cause of Crohn's disease is unknown, but genetics is one of the many areas being explored as a potential culprit. Since Ashkenazi Jews also have a higher risk for Crohn's, the genetic link is being explored as a possible explanation. One study measured the risk of having the disease in Ashkenazim by checking the genetic makeup of a group of Ashkenazim with Crohn’s and a group without it. Their genes were searched for identified and suspected risk factors for Crohn's.
The occurrence of Crohn's was found to be comparable to non-Ashkenazim populations, leading the researchers to suspect that an unidentified genetic culprit is responsible for the high prevalence of Crohn's amongst European Jews.
Genetics-based diseases are often caused by variations in the genetic material within an individual. Human chromosomes contain the genetic material that helps provide instructions for how the body operates. People have 46 pairs of them in their cells, inherited from their mother and their father. When variations happen within the chromosomes, they can lead to malfunctions of the body or increased risks for disease.
Among the parts of the genetic code that researchers are looking at for a possible cause to Crohn's are chromosome 5 and chromosome 10, according to the National Institute of Health (NIH). Chromosome 5 is one of the largest human chromosomes and chromosome 10 plays at least some role in governing the body's immune response. Genetics are not the only factor that could cause Crohn's. Environmental aspects like diet, pollution, and even smoking are being explored as well as the potential for an unknown viral or bacterial cause.
The high frequency of Crohn's disease in the Ashkenazim very likely has a genetic cause, said Dr. R. Balfour Sartor, who is a professor of medicine, microbiology, and immunology at the University of North Carolina at Chapel Hill. “The connection almost certainly is genes that are preferentially found in the Ashkenazi Jewish population,” said Dr. Sartor, who is also the Crohn’s & Colitis Foundation of America’s chief medical adviser.