CARRIER SCREENING

Carrier screening is a genetic test used to identify individuals who carry a single copy of a gene mutation for a specific genetic disorder. These individuals are called carriers. Carriers do not typically show symptoms of the disorder because they have one normal copy of the gene, which usually prevents the development of the disorder.  When both parents are carriers for the same genetic disorder, there is a risk that their child might inherit two copies of the mutated gene – one from each parent. In this case, the child would be affected by the disorder with a 25% chance. This inheritance pattern works in 2 possibilities;

1) Autosomal Recessive Inheritance:
Many genetic disorders are inherited in an autosomal recessive manner Carriers have one normal copy and one mutated copy of the gene. They typically do not show symptoms of the disorder because the normal copy compensates for the mutated one. When two carriers have children, there's a 25% chance that the child inherits two normal copies (not a carrier), a 50% chance of inheriting one normal and one mutated copy (carrier), and a 25% chance of inheriting two mutated copies (affected).

2) X-Linked Recessive Inheritance:
Some genetic disorders are linked to the X chromosome. If a woman is a carrier of an X-linked recessive disorder, she has one normal X chromosome and one with the mutation. Since men have only one X chromosome, if they inherit the mutated X chromosome, they will be affected. Sons of a carrier mother have a 50% chance of being carriers and a 50% chance of being affected. Daughters of a carrier mother have a 50% chance of being carriers and a 50% chance of being carriers like their mother.

 Carrier screening helps couples understand these inheritance patterns and their implications for their future children. If both partners are carriers for the same genetic disorder, there are options to mitigate the risk of having an affected child. These options include prenatal testing, preimplantation genetic testing (PGT), or adoption. Genetic counseling is an integral part of carrier screening, as it provides couples with detailed information about the specific disorder, inheritance patterns, and available options for family planning based on the screening results.