天津及周边地区苯丙氨酸羟化酶基因突变谱和新突变分析

目的 分析天津地区人苯丙氨酸羟化酶(phenylalanine hydroxylase gene,PAH)基因突变谱,明确本地区该基因突变类型和特点,为遗传咨询和产前基因诊断提供科学依据.方法 用聚合酶链反应-单链构象多态、变性高效液相色谱法和DNA测序法对天津及河北等地99例已确诊各种类型苯丙酮尿症患儿基因组DNA进行PAH全基因13个外显子分析.结果 全基因共检出41种突变,含错义突变22种、无义突变7种、剪接位点突变9种和缺失突变3种.其中新突变6种(IVS3nt+1g→a、A165D、Q301X、G344D、P362L和R413G).198个PAH等位基因突变总检出率为93.94%.结论 天津及周边地区PAH基因突变谱广、遗传异质性高,一些常见突变的发生频率与以往报道的地域分布略不同.

Mutation spectrum of phenylalanine hydroxylase gene in patients with phenylketonuria in Tianjin and surrounding areas of Northern China

Objective To investigate the characteristics of the phenylalanine hydroxylase (PAH)gene mutations in patients with phenylketonuria (PKU) in Tianjin and surrounding area, in order to provide basic information for genetic counseling and prenatal gene diagnosis. Methods All of the 13 exons and flanking introns of the PAH gene from 99 patients with PKU were amplified by polymerase chain reaction and analyzed by single strand conformation polymorphism (SSCP), denaturing high performance liquid chromatography (DHPLC) and DNA sequencing. Results Mutations were found in all exons or flanking introns of the PAH gene except for exons 9 and 13. A total of 41 different mutations were identified which corresponded to 93. 94% (186/198) of the PAH alleles, including 22 missense mutations (53. 6%), 7nonsense mutations (17.1%), 9 splicing junction mutations(22.0%), and 3 deletion mutations (7.3%).Six novel mutations (IVS3nt+1g→a, A165D, Q301X, G344D, P362L and R413G) were identified and another 6 mutations (S16fsdelCT, R71H, IVS5nt+1g→a, G239S, R243X and R261X) were reported in Chinese population for the first time according to the databases from http://www. pahdb. mcgill. ca. The most common mutations included 243Q (36/198,18.18%), V399V (22/198, 11. 1%), R111X (19/198,9.6%), E6nt-96A→g (18/198, 9.1%), R413P (15/198, 7.6%) and Y356X (13/198, 6. 6%). In addition, 4 silent mutations (except V399V) in exons and 8 variations in introns were found in this study.The IVS1nt + 40t→g and IVS10nt-31g→a were confirmed as novel variations by international PAH databases and IVS5nt-54g→a was the first report in China. Conclusion The frequencies of six common mutations were close to that in Beijing area of China, but it was different in sequence. The extensive mutation spectrum of the PAH gene showed higher heterogeneity in Tianjin and surrounding areas of Northern China comparing with other reports. According to this report, exons 7 and 11 are the hot spots and should be detected first for PAH gene quick diagnosis in this area, then comes exons 3, 6 and 12, and finally exons 5, 10 and others.