Anyone of Ashkenazi (German or Eastern European) ancestry should be screened for Canavan disease, as well as anyone with a family history of Canavan disease. Persons of Jewish ancestry (Ashkenazi, Sephardic or Mizrahi) should also consider carrier screening for the full list of genetic diseases which affect these populations.
Whether the sample taken is blood or saliva, an enzyme test, which does require a blood sample, is highly recommended as the most reliable screening for Tay-Sachs disease, which is one of the most serious of the diseases on the Ashkenazi panel.
In a couple where both partners are of Jewish heritage, the usual practice is to screen the woman first, generally at her OB/GYN office. If she is found to be a carrier, her partner should be screened for the disease or diseases she carries.
If only one partner is of Jewish heritage, that partner should be screened first. If he or she is found to be a carrier, the other partner can then be screened for the disease or diseases carried by the first partner. In the case of a couple where one member has Jewish ancestry and the other does not, and the Jewish member is found to be a carrier, full gene sequencing of the relevant gene in the non-Jewish member should be considered.
If the couple is already pregnant, both partners are often screened at the same time, to save time in the event that they are both carriers.
In the case of a woman who wishes to become pregnant on her own, or same-sex parents, screening recommendations depend on the heritage of the persons from whom the egg and the sperm originate. For instance, if a Jewish woman is using donor sperm, she should be screened, and if she’s a carrier, her donor should be screened for the disease(s) she carries.
For more information on the screening process, watch the video A Genetic Counselor on Screening