唐山市苯丙酮尿症患儿筛查及PAH基因突变情况分析

摘要：目的　分析唐山市苯丙酮尿症（PKU）患儿筛查结果及苯丙氨酸羟化酶（PAH）基因突变的情况。方法　选取2015年1月—2018年12月唐山市新生儿303 777例，通过茚三酮免疫荧光法检测新生儿足跟血中苯丙氨酸（PA）含量。再利用聚合酶链反应（PCR）和基因测序的方法对筛查出的PKU患儿PAH基因进行检测。结果　303 777例新生儿初步筛查共发现609例可疑阳性，召回其中411例（67.49%）进行复查，确诊42例（13.8/10万）。42例PKU患者的PAH基因测序显示，在84条染色体上共检测到62个（73.81%）12种突变，其中错义突变8种，无义突变2种，缺失突变1种，剪接突变1种。患者PAH基因突变分布在第2、3、6、7、9外显子上，其中第7外显子最多（35个，56.45%），其次为第3外显子（14个，22.58%）。最常见的突变基因为Exon7-R243Q（18个，29.03%）和Exon3-R111X（10个，16.13%）、Exon7-R261Q（10个，16.13%）。筛查中发现1例典型PKU患儿，该患儿在PAH基因外显子区域同时发现2处杂合突变：c.208-210delTCT（缺失突变）和c.964G＞A（鸟嘌呤＞腺嘌呤）。结论　唐山市新生儿PKU发病率略高于全国，PAH基因突变以错义突变为主，第7外显子是唐山市患儿PAH基因高频突变位点。

Screening and analysis of PAH gene mutations in children with phenylketonuria Tangshan city

Abstract: Objective　To analyze the screening results and mutations of phenylalanine hydroxylase (PAH) gene in children with phenylketonuria (PKU) in Tangshan. Methods　From January 2015 to December 2018, 303 777 newborns in Tangshan were selected to detect the content of phenylalanine (PA) in the heel blood by ninhydrin fluorescence method. The polymerase chain reaction (PCR) and gene sequencing methods were used to detect the PAH gene in PKU children. Results　A total of 609 suspected positive cases were found in the preliminary screening of 303 777 newborns. Among them, 411 cases were recalled for re-examination. The recall rate was 67.49%, 42 newborns were diagnosed, and the incidence rate was 13.8/100 000. The PAH gene sequencing in 42 PKU patients showed that 62 mutations were detected on 84 chromosomes, and the detection rate was 73.81%. Twelve mutations were detected, including 8 missense mutations, 2 nonsense mutations, 1 deletion mutation, and 1 splice mutation. The PAH gene mutations of patients were distributed in exons 2, 3, 6, 7, and 9, with the most exon 7 (35, 56.45%), followed by the third exon (14, 22.58%). The most common mutant genes were Exon7-R243Q (18, 29.03%), Exon3-R111X (10, 16.13%) and Exon7-R261Q (10, 16.13%). One child with typical PKU was found in the screening. Two heterozygous mutations were simultaneously found in the exon region: c.208-210delTCT (deletion mutation) and c.964G>A (guanine>adenine). Conclusion　The incidence of neonatal PKU is slightly higher in Tangshan than that in the whole country. The PAH gene mutations are mainly missense mutations. Exon 7 is the high-frequency mutation site of PAH gene in children in Tangshan.