1. Who is Ashkenazi Jewish?
2. Why are these diseases more common in Ashkenazi Jewish people?
3. Which Ashkenazi Jewish genetic diseases does DNA Direct test for?
4. Should we have Ashkenazi Jewish genetic testing if only one of us is Jewish?
5. If some but not all of my ancestry is Ashkenazi Jewish, should I still consider Ashkenazi Jewish Genetic Testing?
   
6. When should Ashkenazi Jewish genetic testing be performed?
7. What if I’m a carrier?
   
8. What if both of us are carriers?
9. What if one partner is a carrier but the other is not?
10. Are there diseases that are more common in Sephardic Jewish people?
11. Are there other diseases that are more common in Ashkenazi Jewish people?
12. Why do these tests look for just one or several mutations in a gene instead of looking at the whole gene?

1. Who is Ashkenazi Jewish?

The term "Ashkenazi" refers to someone whose Jewish ancestors originally came from central or eastern Europe (e.g. Russia, Poland, Germany, Hungary, Lithuania, etc). Jewish people whose ancestors are from the Mediterranean or Middle Eastern regions are known as “Sephardic.” Sephardic Jews are at risk for different hereditary conditions than Ashkenazi Jews.

2. Why are these diseases more common in Ashkenazi Jewish people?

Certain gene mutations occurred by chance among the founders of the Ashkenazi Jewish population, the individuals who immigrated to Eastern Europe at the time of the Diaspora (70 A.D.). This is known as a "founder effect". Prior to this time these diseases were no more common in Jewish people than in any other population. Since Jewish individuals tend to marry within their faith, the gene mutations that were present in the founders of the population remained within the community and increased in frequency over time.

3. Which Ashkenazi Jewish genetic diseases does DNA Direct test for?

We currently offer carrier testing for the following autosomal recessive diseases, all of which are more common in the Ashkenazi Jewish population: Tay-Sachs disease, Canavan disease, Gaucher disease, Familial dysautonomia, Niemann-Pick disease, Fanconi anemia, Bloom syndrome, and Mucolipidosis Type IV. In addition, as European Caucasians, Ashkenazi Jewish individuals are at increased risk to be carriers of cystic fibrosis. The carrier rates for these diseases range from approximately 1 in 14 to 1 in 127.

4. Should we have Ashkenazi Jewish genetic testing if only one of us is Jewish?

Yes. Ashkenazi Jewish genetic testing is recommended for couples with one Ashkenazi Jewish partner. Although the diseases we screen for are more common in individuals of Ashkenazi Jewish background, many of them can also occur in non-Jewish individuals. It is best to start with testing the Ashkenazi Jewish partner and to test the non-Jewish member of the couple only if the Jewish partner is a carrier of any of the diseases.

5. If some but not all of my ancestry is Ashkenazi Jewish, should I still consider Ashkenazi Jewish Genetic Testing?

Yes. Because these conditions can affect individuals of other ethnicities, it may be important to consider carrier testing if you have partial Jewish ancestry.  

6. When should Ashkenazi Jewish genetic testing be performed?

The ideal time for Ashkenazi Jewish genetic testing is prior to pregnancy. This affords a couple the greatest number of options if both are found to be carriers of the same disease. The most cost-effective alternative is to screen one member of a couple first. If that person is a carrier of any of the diseases, then her/his partner can be screened for that/those disease(s) only. If that person is not a carrier of any of the diseases, then her/his partner does not need to be screened. When time is a factor, either because a pregnancy is already underway or a couple is very anxious to become pregnant, the best alternative may be to screen both members of a couple simultaneously. Your healthcare provider can advise you about which option is preferable in your situation.

7. What if I’m a carrier?

It is important to remember that carriers are typically healthy people who are not at risk of developing the disease themselves. If you learn that you are a carrier of one or more of these diseases, discuss testing your partner if he or she hasn’t tested already. Couples in which both partners are carriers have a 1 in 4 (25%) chance with each pregnancy of having an affected child.

8. What if both of us are carriers?

If you know that both you and your partner are carriers of the same disease, there is a 1 in 4 (25%) chance of having a child with the disease. There are several options for couples at risk for having an affected child, including prenatal testing (CVS and amniocentesis) and an assisted reproductive technique known as PGD, or preimplantation genetic diagnosis. If you decide to consider these options, genetic counseling is strongly recommended.

9. What if one partner is a carrier but the other is not?

When one parent is a carrier of a particular disease and the other parent is not a carrier, the couple is not at increased risk to have a child with that disease. Instead, there is a 1 in 2 (50%) chance of having a child who is an unaffected carrier like the one parent.

10. Are there diseases that are more common in Sephardic Jewish people?

Yes. They include beta-thalassemia, familial mediterranean fever, glucose-6-phosphate dehydrogenase deficiency, and glycogen storage disease type III.

11. Are there other diseases that are more common in Ashkenazi Jewish people?

There are a number of other conditions that are more common in Ashkenazi Jewish people than other ethnic groups and for which carrier screening is available. These conditions include glycogen storage disease type 1a, maple syrup urine disease, and nonsyndromic hearing loss (connexin 26). There are also several other conditions that are seen more commonly in people with Ashkenazi Jewish background and which have an autosomal dominant inheritance pattern (meaning, only one affected gene needs to be inherited). Testing for these diseases is appropriate mainly when there is a family history of the disease, or when the person being tested is exhibiting symptoms of the disease. These diseases include torsion dystonia, hereditary breast and ovarian cancer (BRCA1 and BRCA2), and familial hyperinsulinemia.

12. Why do these tests look for just one or several mutations in a gene instead of looking at the whole gene?

In most cases, there is no need to read through the genes entirely, as the disease-causing mutations are known to be located in very specific areas of the genes. This is similar to looking in a large textbook for a particular typographical error — It is much more effective to be able to look for a misspelled word on a specific line of a certain page in the book as compared to reading through every letter of every word of the entire book.