What genetic condition is caused by a mutation in an autosomal gene affecting phenylalanine metabolism?

Phenylketonuria (PKU) is a genetic disorder caused by a mutation in the gene that is responsible for producing the enzyme phenylalanine hydroxylase. This enzyme is crucial for converting phenylalanine, an amino acid found in many protein-containing foods, into another amino acid called tyrosine. When this enzyme is deficient or absent due to the mutation, phenylalanine accumulates in the body, leading to toxic levels that can cause severe neurological damage if not managed.

This condition is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to express the disorder. Management of PKU involves a strict diet low in phenylalanine to prevent the harmful effects of accumulation.

The other options listed are associated with different genetic causes or do not involve phenylalanine metabolism specifically. Cystic fibrosis results from mutations in the CFTR gene affecting ion transport, sickle cell anemia is caused by mutations in the hemoglobin gene leading to abnormal red blood cells, and Huntington's disease results from repeat expansions in the HTT gene leading to neurodegeneration. Thus, the specificity of the disorder associated with phenylalanine metabolism firmly identifies