Shintaku H
Department of Pediatrics, Osaka City University Medical School.
Nihon Rinsho. 1992 Jul;50(7):1542-7.
The hyperphenylalaninemias are caused by the defect of either phenylalanine hydroxylase (PAH) or tetrahydrobiopterin (BH4) cofactor. The former is diagnosed as phenylketonuria (PKU) or benign hyperphenylalaninemia, based on the serum phenylalanine values. The latter, so called malignant hyperphenylalaninemia, includes three enzyme defects, dihydropteridine reductase (DHPR), 6-pyruvoyl tetrahydropterin synthase (PT PS) and guanosine triphosphate cyclohydrolase (GTP-CH). Excess phenylalanine and its metabolites cause brain damage before 6 years of age. Deficiency of BH4 impairs two other hydroxylases (tyrosine and tryptophan), and severe neurological symptoms develop because of the lack of neurotransmitters. Tyrosinemia I, II, and III are different enzyme defects, fumarylacetoacetate hydrolyase (FAH), hepatic tyrosine aminotransferase (TAT), and 4-hydroxyphenylpyruvate acid oxidase, respectively. Tyrosinemia I is associated with severe involvement of the liver, kidney and central nervous system. Tyrosinemia II has mental retardation, palmar hyperkeratosis and corneal ulcers. Tyrosinemia III has mild mental retardation but no eye or skin manifestations.
高苯丙氨酸血症是由苯丙氨酸羟化酶（PAH）或四氢生物蝶呤（BH4）辅因子缺陷引起的。前者根据血清苯丙氨酸值被诊断为苯丙酮尿症（PKU）或良性高苯丙氨酸血症。后者，即所谓的恶性高苯丙氨酸血症，包括三种酶缺陷，二氢蝶呤还原酶（DHPR）、6-丙酮酰四氢蝶呤合酶（PT PS）和鸟苷三磷酸环化水解酶（GTP-CH）。过量的苯丙氨酸及其代谢产物在6岁前会导致脑损伤。BH4缺乏会损害另外两种羟化酶（酪氨酸和色氨酸），由于缺乏神经递质，会出现严重的神经症状。酪氨酸血症I、II和III是不同的酶缺陷，分别为延胡索酰乙酰乙酸水解酶（FAH）、肝酪氨酸转氨酶（TAT）和4-羟基苯丙酮酸氧化酶。酪氨酸血症I与肝脏、肾脏和中枢神经系统的严重受累有关。酪氨酸血症II有智力发育迟缓、手掌角化过度和角膜溃疡。酪氨酸血症III有轻度智力发育迟缓，但无眼部或皮肤表现。
