Phenylketonuria is an autosomal recessive hereditary disease and is the most common congenital amino acid metabolic disorder. The main clinical manifestations include distinctive features such as intellectual disability, light skin and hair pigmentation, and a mouse-like urine odor, which is named after the large amounts of phenylketone acid metabolites excreted in the urine. The incidence of this disease varies by race and region, and the overall incidence in China is approximately 1:11,000, meaning one in eleven thousand. The incidence is higher in the northern population than in the southern population, though it is not particularly high.