苯丙酮尿症是先天性酶缺陷引起的氨基酸代谢障碍的一种遗传病。本病发病率较高,我国约为1/10,000～1/20,000。人群中致病基因携带者为1:60,约占智能低下儿的10％。本病是我国计划生育和优生工作中重点防治的疾病之一。临床表现:患儿出生时一般正常,到4～9个月后,开始出现各种临床表现: Phenylketonuria is a genetic disorder of amino acid metabolism caused by congenital enzyme defects. The incidence of this disease is high, our country is about 1 / 10,000 ~ 1 / 20,000. Pathogenicity in the population of carriers of 1:60, accounting for about 10% of children with mental retardation. The disease is one of the key diseases in our family planning and eugenics work. Clinical manifestations: Children are generally normal at birth, to 4 to 9 months after the start of a variety of clinical manifestations: