A carrier screen analyzes a person’s genes to determine if that person is a carrier of a recessive or X-linked condition. Expanded Carrier Screening looks at up to 289 different hereditary conditions that, together, occur in 1 in 550 births.
Recessive disorders are caused by changes (called mutations) in a person’s genes. Every person has two copies of most genes, one inherited from each parent. A recessive disease occurs when both copies of the same gene have a mutation.
A carrier is someone who has only one gene with a mutation and one gene that is unaffected. Carriers are typically symptom-free and do not know they carry a mutation. In some instances, the condition is inherited differently — only the female needs to be a carrier to have a baby at risk. Fragile X syndrome is an example of this.
Most of us are carriers of a handful of genetic diseases that do not impact our everyday lives. However, these conditions can be passed, unknowingly, to a child. If both members of a couple are carriers of the same recessive condition, they have a 1 in 4 chance with each pregnancy to have a child affected with a genetic disease.
Of the conditions that we test for:
- Many improve with early intervention (e.g., Wilson disease and phenylketonuria)
- Some carry a risk for intellectual disability (e.g., Fragile X syndrome and Niemann-Pick disease)
- Several have limited or no treatment options (e.g., spinal muscular atrophy and Canavan disease)
- 70% of individuals screen positive for one or more conditions on the Expanded Carrier Screen
- 1 in 40 couples test positive for the same condition on the Expanded Carrier Screen
Access to such valuable information before or early in pregnancy allows time to make better family planning choices.