Carrier screening is undergoing significant changes, evolving from focusing on specific genetic mutations within at-risk populations to being accessible to nearly all prospective parents who can afford it. This modern testing can evaluate hundreds of genes, providing individuals with information to make more informed reproductive choices. However, the widespread availability of expanded carrier screening raises questions about its appropriateness for everyone.
This topic was a central point of discussion at the recent annual conference of the Progress Educational Trust in London. To understand the implications, it is essential to grasp the fundamentals of genetics. Human cells contain 23 pairs of chromosomes, which house thousands of genes. Genes can exist in different forms known as alleles. For example, a dominant allele only requires one copy to manifest a trait, such as the allele for brown eyes. In contrast, a recessive allele requires two copies for the trait to be expressed, as seen with the allele for blue eyes.
The stakes increase when considering genes that influence disease risk. In many cases, possessing a single recessive gene does not pose apparent health problems for an individual. However, a genetic disease may arise in offspring if both parents are carriers of the same recessive gene. This results in a 25% chance of having an affected child, which can be unexpected for parents unaware of their carrier status, especially if there is no prior family history of the condition. As the practice of expanded carrier screening grows, understanding its benefits and limitations remains crucial for potential parents.
Source: https://www.technologyreview.com/2025/12/12/1129344/expanded-carrier-screening-is-it-worth-it/