What does it mean to be a carrier of a genetic disease?

Being a carrier of a genetic disease means that the individual does not exhibit symptoms of the disease but possesses one copy of the recessive allele associated with it. This allows them to pass the genetic mutation on to their offspring, even though they themselves might not show any signs or symptoms of the disorder.

For example, in many recessive genetic diseases, an individual needs to inherit two copies of the recessive allele (one from each parent) in order to manifest the disease. Carriers typically have one normal allele and one mutated allele, and because they have the normal allele, they do not show symptoms.

In contrast, individuals who show symptoms of the disease usually have two copies of the recessive gene, meaning they would not be classified as carriers. Being a carrier does not confer immunity to the disease; it simply means that while the individual is unaffected, they can still pass the genetic trait to future generations. This understanding is crucial in the context of genetic counseling and assessing the risk of inheritance for potential offspring.