All the above diseases, except the Fragile X Syndrome, are inherited in a mode known as autosomal recessive inheritance. This means that couples may be at risk of having a sick child only if both partners carry the same defective gene. The risk of a carrier-couple to have a sick child is 25%.

The Fragile X Syndrome is inherited in a different way, to be explained later. The screening aims at finding carrier couples, so that the couple can decide on prenatal diagnosis.

NOTE: the screening does not include all possible genetic diseases.

What should a couple do in order to understand whether they carry a gene for one of the tested hereditary diseases?

First, one of the partners takes a blood test to determine whether they carry a gene to one of the diseases. If confirmed as a carrier, we recommend the other partner be tested as well. If the tests show this partner is not a carrier – the risk for the couple is very low. If they are carriers, the couple will be invited to the genetic counseling clinic for explanations about the findings and the possibilities of prenatal diagnosis.

When is Carrier detection test for these genes recommended?

It is preferable and recommended to perform the tests before the pregnancy, but they can be performed during pregnancy as well. It is advisable to perform it as early as possible, in order to enable, if necessary, CVS or amniocenthesis tests. Tests for carrying these genes will be preformed only if the woman is less than 18 weeks pregnant.

How will you choose the tests appropriate for you?

Further ahead there comes an explanation about each of the diseases, and for which ethnic groups they are recommended. In addition, you may consult our staff in the clinic about choosing the tests.

NOTE:

I. Tay-Sachs carrier detection tests are recommended for the whole population and are conducted, free of charge, by the ministry of health.

II. For couples of Kurdish, Mediterranean, Middle Eastern and Indian origin it is of major importance to check whether they Thalassemia carriers, by a blood count in your local health service clinic (Kupat Holim).

For information about test times,

place and fees,

call 24 hours a day 02-6776995.

Cystic Fibrosis (CF):   Cystic Fibrosis is an hereditary disease that causes severe respiratory and digestive disorders. The disease is incurable, and the treatment aims at alleviating the symptoms through medications and vigorous physiotherapy. As a result of complications of the disease, the life span of CF patients is shorter than average.

The disease exists in all ethnic groups, though more frequent in some. Among Ashkenazi Jews the frquency of carriers is about 1:2,500 and about 1:15,000 among Jews of Moroccan origin. The disease is very rare among Jews of Iraqi and Iranian origin. The frequency of carriers in the population varies according to origin, between 1:25-1:100.

More than 95% of Ashkenazi and Tunisian carriers can be detected, as well as about 85-90% of carriers of Moroccan, Turkish and Georgian origin. Carriers of the genes can not be identified among people of Yemenite, Iraqi and Kurdish origin. Therefore, the test for CF carriers is currently offered according to origin: In couples where only one of the partners is Ashkenazi, this partner will be tested first. The test is not offered to couples where one or both partners are of Iraqi, Kurdish or Yemenite origin.

Canavan Disease: Canavan disease is a serious hereditary disease, where the substance acetyl-aspartate accumulates in the brain. As a consequence, the baby’s brain cells deteriorate, resulting in severe mental and physical retardation, and death.

 The disease is relatively common in Ashkenazi Jews, about 1:10,000 births, and very rare in other ethnic groups. About one out of every 50 Ashkenazi Jews is a carrier of Canavan Disease.

The tests are offered only to couples where both partners are Ashkenazi or partly Ashkenazi. Most carriers can be identified by testing for two mutations in the gene associated with the disease.

Fanconi Anemia:  Fanconi Anemia is a serious hereditary disease, whose main symptoms are severe anemia and increased tendency for malignant tumors. In some cases there are anomalies in the upper limbs, short stature and mental retardation.

The disease occurs in about 1:30,000 births of Ashkenazi Jews, and less in Jews of other origins. The frequency of carriers among Ashkenazi Jews is about 1:90, most of whom can be identified by testing for one mutation. Note that there are several genes associated with Fanconi Anemia, but only one of them is known.

The test is offered only to couples where both partners are Ashkenazi or partly Ashkenazi.

Bloom Syndrome:  Bloom Syndrome is an hereditary disease whose main symptoms are growth retardation, sun-light sensitivity and a tendency for tumors at a young age.

The frequency of the disease among Ashkenazi Jews is about 1:40,000 births. It is more rare in other ethnic groups.

The frequency of carriers among Ashkenazi Jews is about 1:100, most can be identified through testing for one mutation.

The test is offered only to couples where both partners are Ashkenazi or partly Ashkenazi.

Familial Dysautonomia:  Familial Dysautonomia is an hereditary disease affecting the autonomic (involuntary) nervous system. This results in disfunction of numerous somatic functions, such as the digestive and respiratory system, as well as in sensory problems.

The disease is relatively common in Ashkenazi Jews, about 1:3,700 births, and very rare in other ethnic groups. About one out of every 30 Ashkenazi Jews carries a gene for Familial Dysautonomia. Most carriers can be detected by testing for two mutations in the gene associated with the disease.

The test is offered only to couples where both partners are Ashkenazi or partly Ashkenazi.

Gaucher Disease: Patients in this disease lack the enzyme glucocerebrosidase. As a result, lipid substance accumulates in the body. The symptoms are: enlarged spleen and liver, and sometimes a certain damage to the bones and anemia. The range of expression of the disease is very wide: some of the patients show no clinical signs, while others have symptoms that may begin in childhood, in youth or only at an older age.

The disease is relatively common among Ashkenazi Jews (about 1:1000 births), and rare in other communities. The frequency of carriers among Ashkenazis is about 1:15, over 90% of whom can be identified. Note that the most common mutation among Ashkenazi Jews causes a relatively mild form of the disease. Since the disease is often mild, there exists a chance that the test will show that the individual tested actually has Gaucher disease.

The test is offered to couples where at least one of the partners is Ashkenazi or partly Ashkenazi.

Mucolipidosis Type 4 (ML4): Our department recently identified the gene causing ML4, which is also an hereditary disease that exists in Ashkenazi Jews. The main symptoms of this disease are psychomotor retardation and various abnormalities of the visual system. The disease occurs in about 1:40,000 births of Ashkenazi Jews, and is rare in other ethnic groups. The frequency of carriers among Ashkenazim is about 1:100. About 95% of the carriers can be identified through checking for two mutations in the gene associated with the disease.

The test is offered only to couples where both partners are Ashkenazi or partly Ashkenazi.

Fragile X Syndrome: Fragile X Syndrome is one of the common causes of mental retardation (1:1250 in boys and 1:2500 in girls). The syndrome is caused by a defect in a gene located on the X chromosome. In this gene there is an area where a certain fragment repeats several times. The number of repetitions can be measured, and a normal gene has up to 54 repeats. If there are over 55 repeats (a condition called pre-mutation), the gene is less stable and the embryo may receive a gene with over 200 repeats (a full mutation). 100% of the boys and 50% of the girls with full mutation are retarded. Such enlargement of the gene occurs only if the mother carries a pre-mutation, not the father. Therefore only women are tested. The larger the number of repeats in the mother, the higher the risk of the embryo to have another enlargement.

The frequency of women carriers in the general healthy population is about 1:300 in all ethnic groups. When identifying a woman as a carrier, a test is offered to check whether the fetus received a normal or enlarged gene.

We send the blood samples to the genetic institute in Sheba hospital in Tel Hashomer. They perform the test and send the results directly to the patient, after about 5 weeks. They invite women identified as carriers for genetic counseling.