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Genetic Screening Tests

17 November 2024

It is crucial to understand that genetic screening tests should either be carried out at the start of pregnancy or prior to becoming pregnant. The purpose of the test is to identify couples, even those without a family history of one or more of the disorders under investigation, who are at risk of passing on certain serious hereditary disorders to their children.

A hereditary disorder is deemed frequent in this context if it affects more than one out of every 40,000 births, or 1:40,000. This occurrence suggests a carrier frequency of roughly one per 100.

Please be aware that early diagnosis is the only way to prevent the pain and challenges associated with identifying and diagnosing a fetus or infant with genetic disorders.

Who funds the screening tests? The free screening tests that identify carriers of genetic disorders are part of the health services basket.

If a woman is identified as a carrier of an X chromosome-related disorder, or if both spouses are found to be carriers of the same hereditary disorder:

  • To learn more about the different options available to them, the couple will be referred to genetic counseling.
  • A diagnostic test (amniotic fluid, or CVS) will be suggested if the woman is already pregnant in order to assess the health of the fetus.

Considering getting pregnant? Are you considering becoming a parent? You should familiarize yourself with the genetic screening tests used to identify carriers of common disorders. Even if there is no family history of one or more of the disorders being tested, it is advised to have them done prior to getting pregnant in an effort to identify couples who are at high risk. Although genetic screening is only done once, you should be updated prior to each pregnancy.

Please be aware that early diagnosis is the only way to prevent the pain and challenges associated with giving birth to a child with a genetic disorder. A genetic screening test is advised for all women planning a pregnancy by the Ministry of Health. The test can help identify carriers of a number of disorders, though it cannot detect all hereditary disorders.

NOTE

NOTE

As of November 15, 2024, a new comprehensive national screening program has been launched in Israel. If you are planning a pregnancy, even if you have been tested in the past, it is recommended that you go through this new screening. The test is designed for couples, so both partners need to attend. Please check with your HMO or the genetic clinics at hospitals to set up an appointment.

Carriers of the disorders under investigation will be able to be identified through genetic screening tests. The vast majority of carriers are in good health and are not aware of their status. A child has a 25% chance of inheriting the disorder if both of their biological parents have it. Even when only the mother is a carrier of an X-chromosome-linked disorder (like Duchenne or fragile X), the child is still susceptible to the disorder.

The distinction between screening and diagnostic tests during pregnancy and prenatal genetic screening tests

Screening tests include blood tests and ultrasounds, among other follow-up tests, that are recommended for women during pregnancy. These tests look at the woman and the fetus to assess the likelihood of having a child with Down syndrome or other defects. Diagnostic tests that allow for a conclusive diagnosis of these (and other) fetal disorders include chorionic villus sampling and amniocentesis. These tests can also be carried out during pregnancy.

Genetic disorders that are inherited

  • A mutation in the genetic material (DNA), which is passed down from parent to child and from generation to generation, is the cause of a hereditary disorder. Common and serious hereditary disorders are screened for as part of the process.
  • When a hereditary disorder affects more than one in 40,000 births, or 1 in 40,000, it is deemed common. A carrier frequency of roughly one out of every 100 is indicated by this incidence.
  • A hereditary disorder is defined as serious if it causes severe morbidity and early mortality.

Funding genetic (hereditary) screening tests

The health services basket includes free screening tests for common hereditary disorders (the list of disorders is updated periodically based on Ministry of Health decisions). The genetic institutes of the hospitals or the HMO may conduct the tests.

For your information, there are more comprehensive genetic screenings that are privately funded. These include screenings for even more uncommon disorders, which marginally reduces the chance of having a child with one of the disorders under investigation.

More information about eligibility for genetic screening tests on the Ministry of Health Hotline (Kol Habriut) website (Hebrew)

When the same recessive (hidden) genetic disorder is discovered to be carried by both parents

  • If both partners are found to be carriers of the same disorder, they will face a 25% chance of having a baby with the same disorder. These couples will be referred to genetic counseling to receive an explanation of the various options available to them.

  • If the woman is already pregnant, a diagnostic test will be recommended to examine the condition of the fetus (CVS or amniocentesis). If the fetus is diagnosed with the tested disorder, the couple can decide whether to turn to the Pregnancy Termination Board. If the woman is not pregnant, you can also consider performing PGT (Preimplantation Genetic Testing).

If the woman is discovered to be a carrier of a disorder linked to the X chromosome (like Duchenne and fragile X),

  • The woman's children, especially the boys, will have a 50% chance of having that disorder.
  • In order to explain the different options available to her, the woman will be referred to genetic counseling.

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