Testing for Jewish Hereditary Disorders
Many populations have genetic disorders because their gene pool is limited. Certain hereditary diseases and conditions are more prevalent among Jewish people. While anyone can be a carrier of Tay-Sachs disease, a recessive hereditary disease of the nervous system that is nearly always fatal, the incidence of the disease is significantly higher among people of Eastern European (Ashkenazi) Jewish descent, which comprises 90 percent of the American Jewish population. Approximately one in every twenty-seven Jews in the United States is a carrier of the Tay-Sachs gene.
Jewish Hereditary Diseases
There are several other genetically inherited diseases that are more common among the Jewish population than the general population. These include familial dysautonomia, cystic fibrosis, canavan disease, glycogen storage disease, fanconi anemia, Bloom syndrome, Niemann-Pick disease, mucolipidosis, and Gaucher's disease. Couples may choose to test themselves only for diseases that might result in a child's death or debilitation. For instance, Gaucher's disease, which is caused by the lack of a certain enzyme, can now be treated. The missing enzyme can be produced artificially to treat patients.
According to the National Human Genome Research Institute, about one in 250 people in the general population are carriers of the recessive gene that causes Tay-Sachs disease. In addition to people of Ashkenazi descent, non-Jewish French Canadians living near the St. Lawrence River and in the Cajun community of Louisiana have a higher incidence of Tay-Sachs.
Most of these diseases are carried by recessive genes, which means the disease can only manifest itself if a child receives the recessive gene from both parents. If the child receives one recessive gene and one dominant gene, he will be a carrier of the disorder but will have no symptoms of the disease. If a carrier marries someone who is not a carrier, there is no chance that they will have a child with the disease. If two carriers have a child there is a one in four chance that they will have a child with the disease and a one in two chance that they will have a child who will be a carrier.
Since it takes two parents who are both carriers of a recessive gene to have a child with the disease, if only one parent is tested and found not to be a carrier, this is enough to guarantee that the couple will not have a child with the disease.
The Screening Process
There are several ways to check to see if either you or your fiancé is a carrier of a hereditary disease. Either or both partners can go to their doctor to be tested for any of the genes. There are also Jewish organizations such as Dor Yisharim that conduct easy, anonymous testing. They often will test both potential partners early in the dating process and notify them of whether the match is recommended or not. The information of who is a carrier stays confidential.
If two Tay-Sachs carriers marry, in-vitro fertilization shows promise. Fertilized ova can be screened to see if they have both Tay-Sachs alleles. Only those ova without the disease are implanted in the woman's uterus. Obviously, couples should speak with their doctors or health professionals about genetic history or other health issues that may arise in their upcoming marriage.