Jewish Genetic Disorders

The "Jewish" genetic disorders are a group of conditions that are unusually common among Jews of eastern European (Ashkenazi) descent. Although these diseases can affect Sephardic Jews and non-Jews, they afflict Ashkenazi Jews more often- as much as 20 to 100 times more frequently, and often multiple times in one home.

Reasons for Jewish Genetic Disorders
Scientists believe that certain disorders tend to be more common among Ashkenazi Jews due to the "founder effect" and "genetic drift." Today's Ashkenazi Jews descended from a small group of founders. And for centuries, for political and religious reasons, Ashkenazi Jews were genetically isolated from the population at large.

• Founder Effect
  The founder effect occurs when populations are started from a small number of individuals of an original population. Geneticists refer to this relatively small group of ancestors as founders. It is believed that most of today’s Ashkenazi Jews descended from a group of perhaps only a few thousand privileged Ashkenazi Jews that lived 500 years ago in Eastern Europe. Prior to this time we presume that these disorders were no more common among Jews than among any other people.
  Today millions of people may be able to trace their ancestry directly to these founders. Thus, even if just a few founders had a mutation, the gene defect would become amplified over time. The Founder Effect of Jewish Genetic Disorders refers to the chance presence of certain genes among the founders of today's Ashkenazi Jewish population.
  
• Genetic Drift
  Genetic Drift refers to the increase in frequency of the genes for these disorders in this group. Because Ashkenazi Jews tended to marry within their faith and community, the relatively high frequency of these genes among Jews did not pass into other communities and the frequency of these genes was not lessened by the introduction of other genes from outside the Ashkenazi Jewish community.

Most Common Jewish Genetic Disorders

1. Mendelian Disorders are the direct result of mutated genes
• Bloom Syndrome
• Canavan Disease
• Crohn's Disease
• Factor XI Deficiency
• Familial Dysautonomia (Riley-Day syndrome)
• Fanconi Anemia
• Gaucher Disease
• Mucolipidosis IV
• Niemann-Pick Disease
• Non-Classical Adrenal Hyperplasia
• Nonsyndromic Hearing Loss
• Tay-Sachs Disease
• Torsion Dystonia


2. Disease Predisposition Genes are disorders which result from the combination of specific genes
• Breast Cancer (BRCA1 and BRCA2)
• Familial Colon Cancer