苯丙酮尿症学龄儿童就学情况随访

目的鉴于来我院就诊的苯丙酮尿症(PKU)患儿大部分都是延误治疗未经新生儿筛查的,他们都有不同程度的脑损伤,我们研究的目的是为了观察这些患儿治疗与学习情况的关连。方法我们对于1996年6月30日以前出生的 42例经典PKU患儿,皆用国产(北京)特殊营养食品治疗者,随访了入学、学习成绩的资料(包括2例新生儿筛查后即刻治疗)。结果 1．2例新生儿筛查后即刻治疗。学习成绩优秀,社会交往方面与正常孩子相同。2．儿童期诊断的经典 PKU 40例是在婴幼儿期或儿童期诊断的(未经新生儿筛查)入学31例(31／40,77．5％,包括推迟入学、不包括学前班和弱智学校),总入学率为77．50％。3．就学儿童的语文成绩均在中等以上,与开始治疗年量相关性较小,但对抽象思维影响很大,因此数学成绩较差。4．父母的文化程度、对治疗的依从性、家庭经济水平、家长与医生营养师、家长之间的交流对取得良好的治疗效果是非常重要的。结论早发现、早治疗,对预防苯丙酮尿症智力低下的发生是十分必要的,出生6 个月以后开始治疗的经典PKU患儿有一定效果,大部分可以就学。     

Argininosuccinate synthetase gene is silenced by CpG methylation in children with phenylketonuria

Objectives

The concentration of tyrosine and the ratio of branch-amino acid to the aromatic amino acid in phenylketonuria (PKU) patients are much lower than that of normal people, which reveal that PKU patients have amino acid metabolism disorder. The aim of the present study was to investigate the arginine level in blood, the expression of argininosuccinate synthetase (ASS), the rate-limiting enzyme in arginine synthesis pathway, and the methylation of ASS in patients with PKU.

Design and Methods

Twenty-five children with PKU and 65 healthy controls were investigated in this study. Blood concentration of arginine was analyzed by automatic amino acid analyzer. The methylation of ASS gene promoter was evaluated by using methylation-specific polymerase chain reaction (MSP) and bisulfite sequencing PCR (BSP) methods, and the mRNA level of ASS was evaluated by semi-quantitative RT-PCR.

Results

Blood concentration of arginine in PKU patients without dietary control was 0.017 ± 0.009 mmol/L while in normal persons was 0.129 ± 0.007 mmol/L, which is statistically significant (P < 0.001). The promoter of ASS was methylated in PKU (15/15, 100%) but not in normal persons (0/15). The mRNA level of ASS in PKU patients was lower than that of normal people, which was well correlated with its methylation status.

Conclusions

The silencing of ASS due to aberrant promoter CpG methylation may be an important mechanism for arginine biosynthesis disorders in PKU. High levels of phenylalanine and low levels of arginine are common characteristics in PKU patients. These findings would extend the current understanding of arginine, ASS in the development of PKU disease.     

16例经典型苯丙酮尿症的产前基因诊断

应用聚合酶链反应－等位基因特异的寡核苷酸斑点杂交、聚合酶链反应－短串联重复序列对１６例经典型苯丙酮尿症（ＰＫＵ）作家系连锁分析，以及应用聚合酶链反应－单链构型多态性，对其进行产前诊断。其中１０例已获验证，结果与产前诊断相符。     

Genotype–phenotype correlations analysis of mutations in the phenylalanine hydroxylase (PAH) gene

The aims of our research were to define the genotype–phenotype correlations of mutations in the phenylalanine hydroxylase (PAH) gene that cause phenylketonuria (PKU) among the Israeli population. The mutation spectrum of the PAH gene in PKU patients in Israel is described, along with a discussion on genotype–phenotype correlations. By using polymerase chain reaction/denaturing high-performance liquid chromatography (PCR/dHPLC) and DNA sequencing, we screened all exons of the PAH gene in 180 unrelated patients with four different PKU phenotypes [classic PKU, moderate PKU, mild PKU, and mild hyperphenylalaninemia (MHP)]. In 63.2% of patient genotypes, the metabolic phenotype could be predicted, though evidence is also found for both phenotypic inconsistencies among subjects with more than one type of mutation in the PAH gene. Data analysis revealed that about 25% of patients could participate in the future in (6R)-l-erythro-5, 6, 7, 8-tetrahydrobiopterin (BH₄) treatment trials according to their mutation genotypes. This study enables us to construct a national database in Israel that will serve as a valuable tool for genetic counseling and a prognostic evaluation of future cases of PKU.     

苯丙酮尿症儿童脑部病变常规MRI及~1H-MRS研究

目的采用磁共振质子波谱成像(1H-MRS)研究苯丙酮尿症(phenylketonuria,PKU)患儿脑白质内病灶的代谢特点,并观察不同白质病变区代谢的变化。资料与方法对8例临床确诊的PKU患儿及性别、年龄相匹配的8名健康儿童(对照组)分别行T1WI自旋回波序列(SE)、T2WI快速自旋回波序列(FSE)及液体衰减反转恢复序列(FLAIR)检查。1H-MRS检查选择侧脑室后角T2WI异常信号区及放射冠正常白质为兴趣区(ROI),测量1H-MRS谱线上氮-乙酰天门冬氨酸(NAA)、胆碱(Cho)及肌酸(Cr)等主要共振峰的面积,并计算下列化合物的比值:NAA/Cr、Cho/Cr、1000*NAA(Cho、Cr)/H2O。结果在T2WI上,所有未经治疗的PKU患儿侧脑室后角周围白质均可见非占位性、斑片状、条带状高信号。1H-MRS显示未经治疗及治疗后PKU白质异常区及放射冠诸代谢产物与正常对照组差异无统计学意义(P>0.05)。结论 MRS可作为无创性研究PKU病理生理过程的方法。     

清远市149612例新生儿疾病筛查结果回顾性分析

目的通过回顾性分析清远市149 612例新生儿疾病四项筛查结果,了解清远市新生儿疾病筛查情况及召回率,为进一步提高新生儿疾病筛查的质量提供依据。方法应用芬兰Ani Labsystems公司提供的筛查试剂盒,对149 612份标本进行促甲状腺激素(h TSH)、苯丙酮尿症(PKU)、葡萄糖-6-磷酸脱氢酶(G6PD)缺乏症实验检测,应用法国Sebia Capillarys全自动毛细管电泳仪测定新生儿血红蛋白,从而检测地中海贫血。结果 2016年1月-2018年9月清远市各分娩单位出生新生儿156 323例,接受新生儿疾病筛查的有149 612例,筛查率为95. 71%,其中PKU可疑阳性1 441例,召回1 387例,确诊3例;先天性甲状腺功能减低可疑阳性5 753例,召回3 380例,确诊1 221例;G6PD可疑阳性10 269例,召回4 210例,确诊2 754例;130 669例新生儿中,α地中海贫血可疑阳性11 582例,召回4 272例,确诊3 305例;β地中海贫血可疑阳性8 606例,召回5 463例,确诊1 041例,其中α地中海贫血复合β地中海贫血220例。结论新生儿疾病四项筛查是先天遗传代谢病早期诊断的有效方法,也是现代预防医学的一项重要内容,可有效避免患儿发生体格和智能不可逆的永久性损伤,对地中海贫血防控、优生优育具有重要深远的意义。     

国产特殊奶方治疗36例苯丙酮尿症患儿疗效观察

３６例经新生儿苯丙酮尿症（ＰＫＵ）筛查阳性患儿在生后２个月内开始治疗，１８例先由进口低苯丙氨酸奶方治疗后转用国产奶方治疗；另１８例全程用国产＂苯酮安＂奶方治疗。结果显示国产奶方治疗后４天左右血苯丙氨酸（ｐｈｅ）浓度降至６００μｍｏｌ／Ｌ以下；于４．７±２．４岁（０．５～１０岁）随访时，他们的体格发育正常，５３．３％智商正常，提示国产奶方疗效满意。     

16例苯丙酮尿症PAH基因Exon7突变的检测

应用选择突变扩增系统方法对１６例苯丙酮尿症患儿ＰＡＨ基因Ｅｘｏｎ７区域的多聚酶链反应扩增产物进行了突变位点的检测。结果在３２个突变位点中Ｒ２４３Ｑ和Ｒ２６１Ｑ突变位点的检出率分别为４６．８８％和９．３８％，二者占整个突变位点的５６．２５％。表明ＰＡＨ基因Ｅｘｏｎ７突变在中国苯丙酮尿症患者中具有很高的发生频率。     

A defective splice site at the phenylalanine hydroxylase gene in phenylketonuria and benign hyperphenylalaninemia among Palestinian Arabs.

Phenylketonuria (PKU) and benign hyperphenylalaninemia (HPA) result from different combinations of mutations at the locus for phenylalanine hydroxylase (PAH). While some of these mutations show widespread ethnic distribution, others are unique to specific communities. We report here the first point mutation common among Palestinian Arabs. The mutation (IVS2nt1) involves a dinucleotide substitution (Gg-->Aa) at the donor splice site of intron 2 of the PAH gene and abolishes a recognition site of the restriction enzyme MnlI. IVS2nt1 is associated with two PAH polymorphic haplotypes, 7 and 42. Homozygotes for this mutation are affected with severe, classical PKU. Compound heterozygotes carrying the IVS2nt1 allele and one of several other yet unknown mutations show different degrees of benign HPA.