Maruo Yoshihiro, Suzaki Masafumi, Matsui Katsuyuki, Mimura Yu, Mori Asami, Shintaku Haruo, Takeuchi Yoshihiro
Department of Pediatrics, Shiga University of Medical Science, Tsukinowa, Seta, Otsu, Shiga, 520-2192, Japan,
World J Pediatr. 2015 May;11(2):181-4. doi: 10.1007/s12519-015-0020-8. Epub 2015 Apr 30.
Phenylketonuria (PKU) is caused by a defect in phenylalanine hydroxylase (PAH). More than 500 mutations have been reported for the gene encoding PAH. However, approximately 1%-5% of these include large deletions and large duplications that cannot be detected by conventional methods.
In this report we tried to fully characterize a PAH-deficient patient. The patient was a 2-year-old Japanese boy who was diagnosed with classical PKU at the time of neonatal screening, which was confirmed by the tetrahydrobiopterin-loading test. PCR-related direct sequencing and multiplex ligation-dependent probe amplification (MLPA) were used to analyze of the PAH of the patient.
Using PCR-related direct sequencing method, we could detect only a heterozygous novel missense mutation: p.136G>C (p.G46R). A second mutation was detected by MLPA. The patient was heterozygous for a novel large deletion of exons 12 and 13: c.1200-?_1359+?del (EX12_13del). For genetic counseling, an accurate genetic diagnosis is often necessary.
Through a combination of MLPA and conventional methods, the success rate of PAH mutation identification can be close to 100%.
苯丙酮尿症（PKU）由苯丙氨酸羟化酶（PAH）缺陷引起。已报道编码PAH的基因有500多种突变。然而，其中约1%-5%包括常规方法无法检测到的大片段缺失和大片段重复。
在本报告中，我们试图全面表征一名PAH缺陷患者。该患者是一名2岁日本男孩，在新生儿筛查时被诊断为经典型PKU，四氢生物蝶呤负荷试验证实了这一诊断。采用PCR相关直接测序和多重连接依赖探针扩增（MLPA）分析该患者的PAH。
使用PCR相关直接测序方法，我们仅检测到一个杂合的新型错义突变：p.136G>C（p.G46R）。通过MLPA检测到第二个突变。该患者外显子12和13存在新型大片段缺失的杂合情况：c.1200-?_1359+?del（EX12_13del）。对于遗传咨询，准确的基因诊断通常是必要的。
通过MLPA与常规方法相结合，PAH突变鉴定的成功率可接近100%。
