In autosomal recessive diseases, a person who carries a single faulty copy of the disease gene is usually healthy (a "carrier"). If both parents are carriers for the same disease, however, the chance of the child being affected is 25% in every pregnancy.
Commonly screened diseases
- Spinal muscular atrophy (SMA)
- Cystic fibrosis
- Beta-thalassemia and sickle cell disease
- Fragile X-related conditions (depending on the scope of carrier screening)
When should it be done?
The ideal time is before pregnancy (the preconception period), so that the results leave time for family planning decisions. It can also be performed during pregnancy. Screening is especially recommended for diseases with a high population frequency or in consanguineous marriages. Expanded panels can cover hundreds of diseases at once. Interpretation of the results should be handled together with genetic counseling.
