What is the inheritance pattern for sickle cell disease?

Sickle cell disease demonstrates an autosomal recessive inheritance pattern. This means that a child must inherit two copies of the mutated gene, one from each parent, to express the disease. Individuals with only one copy of the mutated gene are considered carriers (sickle cell trait) and typically do not show symptoms of the disease, although they can pass the gene to their offspring.

In autosomal recessive conditions like sickle cell disease, the gene responsible for the disorder is located on one of the autosomes (non-sex chromosomes). Because it follows this pattern, the likelihood of two carriers having an affected child is significant, with each pregnancy having a 25% chance of resulting in a child with sickle cell disease if both parents are carriers. This distinguishes the condition from autosomal dominant inheritance, where only one copy of the mutated gene is sufficient for the condition to manifest, or X-linked inheritance patterns, which involve genes located on the sex chromosomes and often demonstrate different patterns of inheritance based on the sex of the offspring.

Furthermore, polygenic inheritance does not apply, as it refers to traits that are controlled by multiple genes, often leading to a continuous range of phenotypes rather than a specific inherited disorder like sickle cell disease.