- This topic has 1 reply, 2 voices, and was last updated 3 weeks, 1 day ago by
.
-
Posts
-
-
-
Carrier screening is a type of genetic testing offered to people who are planning a pregnancy or who are already pregnant, with the goal of identifying whether they carry a genetic change, called a pathogenic variant, associated with a recessive genetic condition. Testing used in the course of reproductive counseling identifies typically healthy, symptom-free individuals who are heterozygous, meaning they carry one working copy and one non-working copy of a particular gene associated with an autosomal recessive or X-linked disorder.
For most autosomal recessive conditions, a person needs to inherit a non-working copy of a gene from both parents to be affected by the condition; a carrier, who has only one non-working copy, is generally healthy because their one working copy is enough for normal function. However, when two carriers of changes in the same gene have children together, each pregnancy carries a twenty-five percent chance that the child will inherit both non-working copies and be affected by the condition. Carrier screening also covers X-linked conditions, where the relevant gene is located on the X chromosome; here, a woman who carries a single non-working copy is usually unaffected or only mildly affected, but each of her sons has an increased chance of being significantly affected, since sons inherit only one X chromosome.
Carrier screening differs from diagnostic testing performed because a person or their family already shows signs of a genetic condition. Rather, it is a proactive, population-based or panel-based approach intended to inform reproductive decision-making before or during a pregnancy, well before any symptoms would ever be expected to appear, since carriers themselves are not affected by the conditions they carry.
It’s worth knowing that carrier screening is different from testing done because someone already has symptoms or a family history pointing to a specific condition. Carrier screening is done ahead of time, before any problem shows up, simply because carriers themselves never show symptoms.
-
- You must be logged in to reply to this topic.