Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong, China.
Chin Med J (Engl). 2011 Aug;124(16):2556-8.
Hyperphenylalaninemia is one of the commonest inborn errors of metabolism affecting approximately 1 in 15,000 livebirths. Among Chinese, BH4 deficiency leading to hyperphenylalaninemia is much commoner than in Caucasians. Exact diagnosis is important for the treatment and genetic counseling. In 2000, newborn screening for phenylketonuria is mandatory by law in China throughout the whole country. However, it is not yet included in the newborn screening program of the Hong Kong Special Administrative Region, China. Published data on hyperphenylalaninemia among HongKong Chinese are largely lacking. We report a 1-year-old Hong Kong Chinese girl with severe 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency. The patient presented with infantile hypotonia and was misdiagnosed as cerebral palsy. She had very mild hyperphenylalaninemia (95 μmol/L), significantly high phenylalnine-to-tyrosine ratio (3.1), and elevated prolactin of 1109 mIU/L. Genetic analysis confirmed a homozygous known disease-causing mutation PTS NM_000317.1:c.259C>T; NP_000308.1: p.P87S in the proband. In our local experience, while the estimated prevalence of hyperphenylalaninemia due to PTPS deficiency was reported to be 1 in 29,542 live births, not a single case of phenylalanine hydroxylase deficiency has been reported. Furthermore, there is a general lack of awareness of inherited metabolic diseases in the community as well as among the medical professionals. Very often, a low index of clinical suspicion will lead to delay in diagnosis, multiple unnecessary and costly investigations, prolonged morbidity and anxiety to the family affected. We strongly recommend that expanded newborn screening for hyperphenylalaninemia should be implemented for every baby born in the Hong Kong Special Administrative Region, China.
高苯丙氨酸血症是影响大约每 15000 例活产儿的最常见的先天性代谢缺陷之一。在中国人中，导致高苯丙氨酸血症的 BH4 缺乏比白种人更为常见。明确的诊断对于治疗和遗传咨询非常重要。2000 年，中国全国范围内通过法律强制对苯丙酮尿症进行新生儿筛查。然而，它尚未纳入中国香港特别行政区的新生儿筛查计划。关于香港华人高苯丙氨酸血症的已发表数据在很大程度上是缺乏的。我们报告了一例 1 岁的香港华人女孩患有严重的 6-丙酮酰四氢蝶呤合酶（PTPS）缺乏症。该患者表现为婴儿性张力减退，误诊为脑瘫。她有非常轻微的高苯丙氨酸血症（95μmol/L），显著高的苯丙氨酸/酪氨酸比值（3.1）和升高的催乳素为 1109 mIU/L。基因分析证实了该患者为纯合子已知致病突变 PTS NM_000317.1:c.259C>T; NP_000308.1:p.P87S。在我们的本地经验中，虽然报道 PTPS 缺乏导致的高苯丙氨酸血症的估计患病率为每 29542 例活产儿 1 例，但尚未报告过苯丙氨酸羟化酶缺乏症的病例。此外，社区和医疗专业人员普遍缺乏对遗传性代谢疾病的认识。通常，临床怀疑指数低会导致诊断延迟、多次不必要和昂贵的检查、延长发病时间并使受影响的家庭感到焦虑。我们强烈建议对中国香港特别行政区的每个新生儿进行扩大的高苯丙氨酸血症筛查。
