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。     

一种新的脂蛋白脂肪酶基因突变(C562→T)

目的:筛查国人(天津地区)脂蛋白脂肪酶基因突变情况,并探讨其对血脂水平的影响。方法:利用聚合酶链反应-单链构象多态性分析技术,对386例患者(血脂正常组278例,血脂异常组108例)的脂蛋白脂肪酶基因进行突变筛查,对可疑突变的扩增样品进行DNA序列测定。结果:在386例样本中,检出1例外显子3C562→T(Leu103→Leu)同义突变杂合子。结论:新LPL突变(C562→T)的发现,对进一步阐述LPL结构与功能的关系有重要的参考价值。     

广东省清远地区地中海贫血基因分型情况分析

目的了解和分析本地区地贫基因型的分布情况,为临床提供依据,防止和降低重型地贫儿的出生率。方法α-地中海贫血基因分型检测应用跨跃断裂点PCR(GAP-PCR)的技术原理进行检测,即在待检的缺失基因片段两端设计引物进行扩增,再通过琼脂糖凝胶电泳,根据电泳片段大小判断检测样品的基因型。β-地中海贫血基因检测采用PCR体外扩增和DNA反向点杂交相结合的DNA芯片技术,按照碱基互补配对原则,通过分子杂交和显色反应,从而确定待检样品的基因型。结果 778例疑为地中海贫血患者标本,共检出地贫731例,检出率为94%。其中α-地贫基因缺失539例,占73.7%,缺失类型主要以αα/--SEA(--SEA缺失杂合子)为主,共检出485例,占阳性率的66%;-α3.7/αα(-α3.7缺失杂合子)检出27例,占阳性率的3.7%;αα/-α4.2(-α4.2缺失杂合子)检出8例;-α3.7/--SEA(-α3.7、--SEA双重缺失杂合子)检出8例,其他基因型较少检出;β-地贫基因突变192例,占26.3%,突变类型主要以CD41-42位点的单突变杂合子为主,检出87例,占阳性率的11.9%,单突变纯合子2例;其次为IVS-Ⅱ-654位点的单突变杂合子,检出53例,占阳性率的7.3%;其余突变类型依次为CD17、-28、CD71-72、CD43的单突变杂合子,双突变杂合子8例。患者中婴幼儿225人次,检出地贫186例,检出率82.6%;婚检和孕检553人次,检出地贫545例,检出率98.6%。结论本地区的地贫检出率较高,主要以α-地贫基因缺失为主,其中又以婚、孕检人群为主。由此可见对婚、孕检人群进行地贫基因检测可以更好的防止和降低重型地贫儿的出生率,从而减轻社会和家庭的负担,实现优生优育。     

脂蛋白脂肪酶外显子9基因突变研究

目的 :筛查国人脂蛋白脂肪酶 (LPL)外显子9基因突变和Ser447→stop突变频率 ,并探讨该突变对血脂水平的影响。方法 :依血脂测定结果 ,将169例分为高甘油三酯血症组(HTG组 ) ,48例和正常甘油三酯组(对照组 )121例 ,利用聚合酶链反应 -单链构象多态性和聚合酶链反应 -限制性片段长度多态性分析技术对待测人群的LPL基因外显子9及其相邻内含子区域进行突变筛查 ,并对典型单链构象电泳图谱携带者进行PCR产物测序。结果 :在169例中检出1例Ser447→stop突变纯合子 ,50例Ser447→stop杂合子 ,未检出其它位点的突变 ;HTG组的Ser447→stop突变检出率 (25.0 % ,12/48)明显低于对照组 (31.4 % ,38/121) ,HTG组的Stop447 等位基因频率(12.5% )明显低于对照组 (16.5% ),两组比较差别均有统计学意义(P<0.01)。结论 :我国人群中LPL外显子9突变种类单一 ,Ser447→stop是一高频率的多态性位点 ,Stop447等位基因可能有轻微的降低血浆甘油三酯的作用。     

广东省东莞市50361例新生儿疾病筛查分析

目的 探讨东莞市新生儿先天性甲状腺功能减低症(CH,简称甲低)和苯丙酮尿症(PKU)的发病率、治疗效果及管理模式,为CH和PKU二级预防提供依据。方法 对本市38所医疗保健机构出生的50361例新生儿采用足跟血滤纸干血斑法进行二种疾病筛查。结果 新生儿65258人,筛查50361人,筛查率77.17%;确诊CH15例,检出率1/3357;PKU1例,检出率1/50361。筛查程序运转良好。结论 新生儿CH和PKU经筛查可早发现,早诊断,早治疗及干预,可使患儿生长发育指标、智能达到同龄水平。成立新生儿疾病筛查中心,进行统一管理,是进行新生儿筛查的最佳管理模式。     

一种新的脂蛋白脂肪酶基因突变（C^56→T）

目的：筛查国人（天津地区）脂蛋白脂肪酶基因突变情况，并探讨其对血脂水平的影响。方法：利用聚合酶链反应-单链构象多态性分析技术，对386例患者（血脂正常组278例，血脂异常组108例）的脂蛋白脂肪酶基因进行突变筛查，对可疑突变的扩增样品进行DNA序列测定。结果：在386例样本中，检出1例外显子3 C^56→T（Leu^103→Leu）同义突变杂合子。结论：新LPL突变（C^56→T）的发现，对进一步阐述IJPL结构与功能的关系有重要的参考价值。     

高苯丙氨酸血症20例诊治体会

血浆苯丙氨酸 (Phe)浓度高于 0 .12 mm ol/L ,称高苯丙氨酸血症 (hyperphenya- aninemia,HPA)。本病是肝内缺乏 Phe羟化酶 (PAH)导致 Phe代谢障碍引起代谢缺陷。也可因辅助因子四氢生物喋呤 (tet- rahr,rodior- erin,BH4 )缺乏引起 ,属常染色体隐性遗传病。HPA分为经典型苯丙氨酸酮尿症(classic- phenylketonuria,PKU,非 PKU高 Phe血症和 BH4 缺乏症三大类 ,是目前可以治疗的先天性代谢障碍病之一。我院 1999— 0 9～ 2 0 0 1— 0 3用细菌抑制法 (Guthrie)在新生儿疾病筛查确诊 2 0例高 Phe血症 ,经早期低 Phe饮食治疗 ,效果满意…     

INSL-3基因QPLPQ序列突变与隐睾

目的:探讨INSL-3基因突变与隐睾发生的相关性及其发生机制.方法:选取临床资料完整的隐睾患者60例,正常对照组(无先天性疾患)15例,提取人外周血白细胞基因组DNA,经聚合酶链式反应(PCR)扩增INSL-3基因2个完整外显子,并行基因纯化、测序,根据试验结果分析其基因突变与隐睾发生的关系,并从分子生物学角度解析其相关发病机制.结果:隐睾患者组检出2例276G/T杂合突变,1例477G/C杂合突变,276G/T杂合突变使其编码的92位谷氨酰胺变为组氨酸,从而引起其编码蛋白一级结构的改变,477G/C突变点不在编码序列之内,不引起编码氨基酸改变.隐睾患者组基因突变率为5.0%(3/60),正常对照组未见突变发生.结论:Q92H可能为致隐睾发生相关位点.而QPLPQ序列突变值得引起关注.     

脂蛋白脂肪酶基因突变的研究

目的：筛查国人脂蛋白脂肪酶(LPL)基因的突变，并探讨其与高甘油三酯血症的关系。方法：对高甘油三酯血症组(48例)和正常甘油三酯对照组(121例)的各扩增片段进行分析，电泳图谱异常者进行PCR产物测序。对于频率较高的多态性位点，引入限制性核酸内切酶位点利用PCR-RFLP进行鉴定。结果：在高甘油三酯血症人群中，检出2例内含子3受位剪接点上游6bp的C→T转换的突变杂合子，1例外显子5Pm^207→Leu突变杂合子，在全部样品中检出1例Ser^447→stop突变纯合子，50例Ser^447→stop杂合子。结论：天津地区人群中存在着LPL基因突变，除Ser^447→stop外，内含子3和外显子5的突变多与高甘油三酯血症相关，可能是高甘油三酯血症的遗传易感因子。     

苯丙氨酸羟化酶基因部分外显子突变研究

目的：探讨苯丙酮尿症(PKU)患者PAH基因突变特点。方法：用PCR—SSCP和PCR—DNA测序法对天津河北等地的70例无血缘关系并已确诊为PKU患者的基因组DNA进行PAH基因外显子3、5、6、7、10、11和12的突变基因分析。结果：70例PKU患者共140条染色体，共发现26种突变，含错义突变14种、无义突变5种、同义突变4种、剪接位点突变2种和缺失突变1种。除4种同义突变外，阳性突变率为64．28％。其中DelS70、R176X、R261X、L385L、IVS5nt 1g→a、A165D、G247R、Y325X、G344E和R413G占总突变种类的38．5％(10／26)。结论：天津河北等地的PAH基因突变类型复杂，有些常见突变的发生频率与以往报道的地域分布略有不同。     

Sapropterin dihydrochloride (Kuvan/phenoptin), an orally active synthetic form of BH4 for the treatment of phenylketonuria

Phenylketonuria (PKU) and mild hyperphenylalaninemia (HPA) are genetic disorders characterized by a deficiency in phenylalanine hydroxylase (PAH), resulting in intellectual impairment if not treated with dietary restriction of phenylalanine intake. Sapropterin dihydrochloride (Kuvan) is an orally active synthetic form of (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4; a cofactor for PAH) that has received Orphan Drug status and Fast Track designation for the treatment of PKU. Phase II and III clinical data demonstrated that Kuvan was a safe and effective therapy in selected patients with HPA and mild-to-moderate PKU who responded to a BH4 loading test. Based on the clinical data, BioMarin Pharmaceutical Inc has estimated that Kuvan could be a potential treatment option for 30 to 50% of the estimated 50,000 patients in the developed world who have been diagnosed with PKU. According to Thomson Scientific's Strategic Drugs Database (SDdb), the worldwide consensus forecast values for Kuvan are approximately US $120, 190 and 260 million for 2008, 2009 and 2010, respectively.     

Structural and mechanistic implications of incorporating naturally occurring aberrant mutations of human dihydropteridine reductase into a rat model

Phenylketonuria (PKU) is a debilitating hereditary disorder related to an individual's inability to convert phenylalanine to its usual tyrosine product. The genetic errors occur in three regions: in the cooperative enzymes phenylalanine hydroxylase (PAH) and dihydropteridine reductase (DHPR), and in the biosynthetic pathway from GTP to the hydroxylation cofactor, tetrahydrobiopterin (BH₄). Many instances of naturally occurring defects in DHPR metabolism have been identified, and in most cases the error has been equated with an altered enzyme gene sequence. Using computer graphics, this report analyses the altered structural characteristics of eight of the enzymes encoded by mutant gene sequence and provides logical explanations for their diminished enzyme activities. In one instance, that of a threonine insertion, a mutant construct of the rat analog has been expressed in Escherichia coli and the DHPR isolated and characterised, confirming the marked changes this insert can create.     

Biochemical analysis of Centaurea depressa phenylalanine ammonia lyase (PAL) for biotechnological applications in phenylketonuria (PKU)

Context: Phenylketonuria (PKU) is the most common hereditary defect of phenylalanine hydroxylase (PAH) enzyme achieving the hydroxylation of phenylalanine (Phe). Phenylalanine ammonia lyase (PAL) converts Phe to a harmless metabolite, trans-cinnamic acid (TCA) in plants and PAL enzyme activity is fairly high in plants rich in flavonoids.

Objective: The study aimed the biochemical analysis of PAL form Centaurea depressa BIEB. (Asteraceae) a flavonoid rich plant. This study may form the main frame of future research efforts for the development of a plant preparation aimed for oral intake in PKU patients in an attempt to enrich their diet by allowing them to ingest some food stuff containing Phe without being exposed to complications.

Materials and methods: PAL was partially purified from the leaves of C. depressa. Enzyme activity was determined in comparison with that of other herbs that reportedly have a high PAL activity. Enzyme optimization was achieved and the PAL protein was detected by western blotting.

Results: C. depressa PAL demonstrated high activity (34.9?±?0.6?U/mg protein). The enzyme was purified by 1.92-fold, which resulted in an activity of 53.30?±?0.2?U/mg protein. The high-performance liquid chromatography analyzes of the PAL activity both before and after purification were in agreement. Western blot of PAL exhibited a 70?kDa protein band. The optimum pH and temperature are pH 8.8 and 37?°C. The optimum activities under gastric and intestinal digestion conditions were observed at pH 4.0 and pH 8.0, respectively.

Discussion and conclusion: PAL activity of C. depressa is high, and does not disappear under different environmental conditions. This enzyme could be used for the development of dietary foods and biotechnological products for patients with PKU.     

5-Lipoxygenase polymorphism and in-vivo response to leukotriene receptor antagonists

OBJECTIVE: To determine whether genetic polymorphisms of the core promoter region of the 5-lipoxygenase gene contribute to the clinical response to leukotriene receptor antagonists. METHODS: We retrospectively genotyped 52 asthmatics for mutations of this gene from four placebo-controlled studies measuring leukotriene receptor antagonist responses. All studies measured bronchodilator response, and bronchial hyperresponsiveness to adenosine monophosphate was measured in three studies ( n = 34). RESULTS: Of the 52 patients genotyped, 40 were homozygous wild type, 12 heterozygous, and none was homozygous mutant. There was no significant difference in any improvements conferred by leukotriene receptor antagonists versus placebo in the forced expiratory volume in 1 s (0.20 l for wild-type homozygotes and 0.01 l for heterozygotes), forced mid-expiratory flow rate (0.16 l/s and 0.14 l/s), peak expiratory flow rate (10 l/min and 29 l/min) and adenosine monophosphate 20% fall in forced expiratory volume in 1 s (2.8-fold shift and 2.3-fold shift) between the two genotypes. CONCLUSION: In our population, screening for this polymorphism as an aid to guiding treatment is probably not worthwhile. In addition, we found no difference between homozygous wild types and heterozygotes in terms of bronchodilator response or bronchial hyperresponsiveness with leukotriene receptor antagonists.     

New insights into tetrahydrobiopterin pharmacodynamics from Pah, a mouse model for compound heterozygous tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency

Phenylketonuria (PKU), an autosomal recessive disease with phenylalanine hydroxylase (PAH) deficiency, was recently shown to be a protein misfolding disease with loss-of-function. It can be treated by oral application of the natural PAH cofactor tetrahydrobiopterin (BH₄) that acts as a pharmacological chaperone and rescues enzyme function in vivo. Here we identified Pah^enu1/2 bearing a mild and a severe mutation (V106A/F363S) as a new mouse model for compound heterozygous mild PKU. Although BH₄ treatment has become established in clinical routine, there is substantial lack of knowledge with regard to BH₄ pharmacodynamics and the effect of the genotype on the response to treatment with the natural cofactor. To address these questions we applied an elaborate methodological setup analyzing: (i) blood phenylalanine elimination, (ii) blood phenylalanine/tyrosine ratios, and (iii) kinetics of in vivo phenylalanine oxidation using ¹³C-phenylalanine breath tests. We compared pharmacodynamics in wild-type, Pah^enu1/1, and Pah^enu1/2 mice and observed crucial differences in terms of effect size as well as effect kinetics and dose response. Results from in vivo experiments were substantiated in vitro after overexpression of wild-type, V106A, and F263S in COS-7 cells. Pharmacokinetics did not differ between Pah^enu1/1 and Pah^enu1/2 indicating that the differences in pharmacodynamics were not induced by divergent pharmacokinetic behavior of BH₄. In conclusion, our findings show a significant impact of the genotype on the response to BH₄ in PAH deficient mice. This may lead to important consequences concerning the diagnostic and therapeutic management of patients with PAH deficiency underscoring the need for individualized procedures addressing pharmacodynamic aspects.     

贵港市150422例新生儿疾病筛查结果分析

目的 了解贵港市新生儿先天性甲状腺功能低下（CH）、苯丙酮尿症（PKU）的筛查率及发病率.方法 CH筛查指标为血促甲状腺素（TSH）,实验方法用时间分辨荧光免疫分析法;PKU筛查指标为血苯丙氨酸（Phe）,实验方法用荧光测定法.结果 CH、PKU的筛查率为47.97%;CH发病率为0.246‰;能随访的PKU筛查阳性的新生儿确诊为0例.结论 加强新生儿疾病筛查的宣传和推广,提高筛查率具有重要意义.开展新生儿疾病筛查,加强筛查阳性新生儿的转诊和随访,可早发现CH及PKU,是提高出生人口素质的重要措施.     

苯丙氨酸羟化酶基因内短串联重复序列多态性应用分析

采用苯丙氨酸羟化酶基因内短串联重复序列扩增片段长度多态性连锁分析法，对２２个苯丙酮尿症家系进行了分析。结果显示；２２个ＰＫＵ患者的家庭均能获得多态信息，其中能获得１００％多态信息的有９个家庭，占分析对象的４０．９％。该方法快速简便，对未知基因突变的ＰＫＵ家系的前前诊断提供了可能性，达到了快速基因诊断的目的。     

潍坊市2000~2014年苯丙酮尿症筛查资料回顾分析

目的 了解潍坊市2000~2014年苯丙酮尿症(PKU)的筛查和确诊患儿情况。方法 查阅潍坊市15年来新生儿疾病筛查年报和患儿病历档案,对PKU筛查和确诊患儿情况进行统计分析。结果 潍坊市PKU筛查覆盖率呈逐年上升趋势,2012年达到最高的99.15%;共确诊患儿136例,检出率为1.22/万,以经典型为主,男性居多,农村患儿数多于城市;规范治疗率69.85%,患儿治疗前后的血苯丙氨酸水平差异有统计学意义(P<0.05)。结论 潍坊市PKU筛查推广工作取得了明显成效,但需加强资料统计工作,实施安全有效治疗、规范随访,可较好改善患儿预后。     

2002-2009年浙江省温州市龙湾区新生儿疾病筛查分析

目的 分析2002-2009年浙江省温州市龙湾区新生儿疾病筛查情况.方法 对2002-2009年浙江省温州市龙湾区出生的46 202名新生儿进行新生儿疾病筛查,在出生72 h,充分母乳喂养后采集足跟血检测血清促甲状腺素（TSH）、苯丙氨酸水平,筛查结果 阳性者及时进行复查确诊.结果 46 202名新生儿中共检出阳性23例（0.05%）,其中先天性甲状腺功能低下症筛查阳性22例,发病率为1/2 100;苯丙酮尿症筛查阳性1例,发病率为1/46 202.确诊患者均由浙江省新生儿疾病筛查中心专家治疗随访.结论 新生儿疾病筛查是先天性甲状腺功能低下症、苯丙酮尿症早期诊断的有效措施之一,可有效防止患儿智力和体格发育低下以及其他器官功能的损害.