河南地区6-丙酮酰四氢蝶呤合成酶缺乏症基因变异分析

Mutation analysis of patients with 6-pyruvoyltetrahydropterin synthase deficiency in Henan

目的:分析河南地区6-丙酮酰四氢蝶呤合成酶缺乏症(PTPSD)基因变异规律及特点,为PTPSD早期诊断、治疗及遗传咨询和产前诊断提供理论依据。方法:选择1998年1月至2018年12月在郑州大学第三附属医院河南省新生儿疾病筛查中心就诊的1906例高苯丙氨酸血症(HPA)患儿,采用荧光分析法测定其血苯丙氨酸(Phe)水平,对血Phe>120μmol/L者进行尿蝶呤谱分析和红细胞二氢蝶呤还原酶(DHPR)活性测定,对临床初步诊断为四氢生物蝶呤缺乏症(BH4D)的79例患儿行HPA相关基因(PAH、GCH1、GFRP、PCBD1、PTPS、QDPR)的高通量测序分析,对筛选出的致病性变异位点进行Sanger测序验证。结果:1906例HPA患儿中,79例临床诊断BH4D,且均为PTPSD,HPA中PTPSD发生率为4.14%;79例患儿158个等位基因中156个检测出变异,检出率为98.73%;共检测到30种变异,第5外显子的变异检出率最高(92/156个,58.97%);变异频率较高的依次为c.259C>T(61/156个,39.10%)、c.286G>A(17/156个,10.90%)、c.155A>G(13/156个,8.33%)和c.272A>G(10/156个,6.41%);共检出6种新的错义变异,分别为c.-77G>T、c.158A>G、c.207G>A、c.262C>T、c.316A>G、c.332C>G。79例患儿检测出38种基因型,其中纯合变异基因型3种,复合杂合变异基因型33种。结论:c.259C>T可能为河南省PTPSD患儿热点突变类型,发现6种新发变异,丰富了其基因突变谱。

Objective To analyze the variation and characteristics of gene mutation in patients with 6-pyruvoyltetrahydropterin synthase deficiency(PTPSD)in Henan province,and to provide the theoretical basis for early diagnosis,treatment,genetic consultation and prenatal diagnosis of PTPSD.Methods One thousand nine hundred and six children with hyperphenylalaninemia(HPA)treated in Henan Neonatal Screening Center,the Third Affiliated Hospital of Zhengzhou University from January 1998 to December 2018 were included.Chemiluminescence was used for pheny-lalanine(Phe)detection in blood or dried blood spots.For patients with Phe concentration>120μmol/L,urine pterin analysis was carried out,and the activity of dihydropteridine reductase(DHPR)was detected.Mutations of the PAH,GCH1,GFRP,PCBD1,PTPS and QDPR in 79 children with tetrahydrobiopterin deficiency(BH4D)were detected by using the high-throughput sequencing.All variations were verified by Sanger sequencing.Results Among the 1906 children,79 cases were diagnosed as BH4D clinically,and they all were PTPSD.The incidence of PTPSD in HPA in Henan was 4.14%.One hundred and fifty-six out of 158 alleles in 79 children were detected,and the detection rate of gene mutation was 98.73%,30 mutations were identified and most of the variants were located in exons 5(92/156 cases,58.97%).Variants of c.259C>T(61/156 cases,39.10%),c.286G>A(17/156 cases,10.90%),c.155A>G(13/156 cases,8.33%)and c.272A>G(10/156 cases,6.41%)were more common.Six novel variations were detected,which included c.-77G>T,c.158A>G,c.262C>T,c.207G>A,c.316A>G and c.332C>G;38 genotypes had been identified,including 3 homozygous mutations and 33 compound heterozygous mutations.Conclusions c.259C>T is the hot-spots gene mutation in Chinese PTPSD patients in Henan province.The identification of 6 new mutations enriches the gene mutation profile.