Which of the following conditions is an example of an autosomal dominant inherited disorder?

Familial hypercholesterolemia is an example of an autosomal dominant inherited disorder because it is caused by a mutation in one of the genes responsible for regulating cholesterol levels in the body, most notably the LDL receptor gene. In autosomal dominant inheritance, only one copy of the mutated gene, inherited from either parent, is sufficient to cause the disorder. This means that individuals with the condition have a 50% chance of passing the mutated gene to their offspring, which is characteristic of autosomal dominant disorders.

In familial hypercholesterolemia, affected individuals typically have high levels of LDL cholesterol, leading to an increased risk of early cardiovascular disease. This condition often presents with early signs of atherosclerosis, and it can occur in individuals who have no family history due to new mutations. This mode of inheritance distinguishes familial hypercholesterolemia from conditions like sickle cell disease and cystic fibrosis, which are autosomal recessive disorders, requiring both copies of the gene to be mutated for the condition to manifest. Down syndrome, caused by an additional copy of chromosome 21, is a chromosomal abnormality rather than a single-gene disorder.