Carrier screening involves testing to see if a person “carries” a genetic variation (allele) associated with a specific disease or trait but the mentioned person is healthy (without any signs and symptoms of disorders). A carrier has inherited a normal and a variant allele for a disease- or trait-associated gene, one from each parent. Most typically, carrier screening is performed to look for recessively inherited diseases when the suspected carrier has no symptoms of the disease, but that person’s offspring could have the disease if the other parent is a carrier of a harmful variant in the same gene.

Information about carrier screening should be provided to every pregnant woman. All pregnant patients and those planning a pregnancy should be offered carrier screening

Carrier screening and counselling ideally should be performed before pregnancy because this enables couples to learn about their reproductive risk and consider the most complete range of reproductive options.

The results indicate a very high prevalence of consanguineous marriage in Oman, as more than half (52%) of marriages are consanguineous. First cousin unions are the most common type of consanguineous unions, constituting 39% of all marriages. (M Mazharul Islam. et al .2012). Because of this study; Importance of carrier testing is very higher than other countries.

Molecular testing used to identify individuals and couples at risk for a child with an autosomal recessive or X-linked genetic disorder

Generally, carriers are healthy.  However, there may be circumstances where individuals may have medical issues (e.g., Fragile X carriers may have risk for premature ovarian failure)

Tier 1 : CF, SMA, Risk Based Screening

Tier 2 : ≥1/100 carrier frequency (includes Tier 1)

Tier 3(RECOMMENDED) : ≥1/200 carrier frequency (includes Tier 2) and X-linked conditions

Tier 4 : <1/200 carrier frequency (includes Tier 3) , Genes/conditions will vary by lab ACMG Recommendations

Carrier screening paradigms should be ethnic and population neutral and more inclusive of diverse populations to promote equity and inclusion All pregnant patients and those planning a pregnancy should be offered Tier 3 carrier screening Tier 4 screening should be considered When a pregnancy arises from a known or possible consanguineous relationship (second cousins or closer) Routine offering of Tier 4 panels

Carrier screening enables couples to become aware of their reproductive options, prenatal testing options, and the opportunity to prepare
for a child with a genetic disorder. It is important to discuss these options with your doctor or clinical genetic counselor to determine which
is most appropriate for you and your family

If you and your partner are carriers for the same autosomal recessive condition, there is a 1 in 4 (25%) chance with each pregnancy, your
child will be affected. For X-linked recessive conditions, only the mother has to be a carrier for her children to be at risk. If the mother is a
carrier of an X-linked recessive condition, there is a 1 in 2 (50%) chance her son will be affected.

Yes. Typically, women are offered carrier screening first because if they are not found to be a carrier, then follow up testing of their partner
will not be necessary. However, it may save time if a couple receives screening concurrently. If you and your partner would like to receive
screening at the same time, inform your doctor(s) so that they may coordinate testing for you.

A genetic counselor is a professional who provides information and support to patients as they make decisions about their genetic health.
Once the carrier screening test is completed, Bion Genetic Counseling help you to get your answer of your question and details of your result. For more information contact with Bion Medical Genetic Laboratory.