中国西北地区苯丙氨酸羟化酶基因突变构成分析

Analysis on mutation spectrum of phenylalanine hydroxylase gene in Northwest Chinese patients with phenylketonuria

目的分析中国西北地区苯丙氨酸羟化酶(PAH)基因的突变特征,为苯丙酮尿症(PKU)基因诊断及遗传咨询提供理论依据。方法联合应用PCR产物直接测序法、基因芯片捕获和二代高通量测序技术对2003年1月—2019年12月在中国西北五省区新生儿疾病筛查中心确诊的326例PKU患儿及其父母的PAH基因启动子、第1~13外显子及其旁侧内含子区域进行基因突变分析。结果在中国西北地区326例PKU患者652条PAH等位基因中检测出105种致病突变,总检出率为87.7%,突变以错义突变、剪切位点突变、无义突变和移码突变为主;大部分突变主要分布在E7(25.2%)、E6(11.8%)、E3(9.2%)、E12(9.2%)、E11(8.3%)、I4(5.2%)、E2(3.5%)和E5(3.5%)中;突变频率较高的PAH基因致病突变是R243Q,与中国北方、韩国比较一致,但显著区别于日本(R413P)、德国(R408W)、以色列(IVS10-11G>A)、意大利(R261Q)、巴西(V388M)和美国(R408W)等国家,其他常见突变类型还包括EX6-96A>G、IVS4-1G>A、R413P、R111X、Y356X、R53H、R241C和IVS7+2T>A;中国西北汉族与西北维吾尔族、回族相比,R243Q、R413P和EX6-96A>G突变的检出率具有显著性差异(P<0.05)。中国西北地区R243Q突变检测率显著高于日本、韩国(P<0.05)。国际上首次报道14种新突变,在中国人群中首次报道9种突变。结论中国西北地区PKU患者PAH基因突变构成与中国北方基本一致,稍区别于日本、韩国等东亚国家,但显著不同于其他西亚、欧洲、美洲国家。中国西北地区不同民族PAH基因突变谱具有其独立保守的特性。中国R243Q突变的起源可能在中国汉族中,R241C、Q232X突变频率的高处在中国回族中,而R413P、F161S、IVS10-11G>A、P281L和IVS11-2A>C突变频率的高位在中国维吾尔族中。

Objective To investigate the mutation characteristics of the phenylalanine hydroxylase(PAH)gene in Northewest Chinese patients with phenylketonuria(PKU)and to provide a theoretical basis for genetic diagnosis and consultation of PKU at the prenatal stage.MethodsThrough combining the methods of PCR direct sequencing,gene chip and high throughput sequencing,we detected the mutations in PAH gene promoter,1-13 exons and adjacent introns among 326 children and their patients,who were recruited from the patients diagnosed by the neonatal disease screening Centers in the five northwestern provinces of China from January 2003 to December 2019.ResultsAmong 326 PKU patients,out of 652 alleles,105 different mutations were detected.The total detection rates were 87.7%.The major types of mutations are missense mutation,splicing mutation,nonsense mutation and frameshift mutations.Most mutations are located in exon 79(25.2%),followed by exon 6(11.8%),exon 3(9.2%),exon 12(9.2%),exon 11(8.3%),intron 4(5.2%),exon 2(3.5%)and exon 2(3.5%).The most common mutation was R243Q,which is the same to the most common mutation in Northern China and Korea,but different from that in Japan(R413P),Germany(R408W),Israel(IVS10-11G>A),Italy(R261Q),Brazil(V388M)and the United States(R408W).The other common mutations included EX6-96A>G,IVS4-1G>A,R413P,R111X,Y356X,R53H,R241C and IVS7+2T>A.The frequencies of R243Q,R413P and EX6-96 A>G mutations of ethnic Han group were significantly different from those of Uygur group.In Northwest China,the frequency of R243Q mutation was significantly higher than that in Japan or Korea(P<0.05).Fourteen new PAH gene mutations were reported for the first time.Additional nine mutations were first identified among the Chinese population.ConclusionAmong Northwestern Chinese,mutation spectrum of PAH gene is similar to that in Northern China,but slightly different from that in Japan,Korea and other East Asian countries,or significantly different from that in West Asian,European and American countries.The PAH gene profiles in Northwest China are independent and conservative.The R243Q mutation is probably originated from Han ethnicity;R241C and Q232X are from Hui ethnicity;and R413P,F161S,IVS10-11G>A,P281L and IVS11-2A>C are from Uygur ethnicity.