Update of the spectrum of mucopolysaccharidoses type III in Tunisia: identification of three novel mutations and <Emphasis Type="Italic">in silico</Emphasis> structural analysis of the missense mutations

Background:Mucopolysaccharidoses type Ⅲ (MPS Ⅲ) are a group of autosomai recessive lysosomal storage diseases,caused by mutations in genes that code for enzymes involved in the lysosomal degradation of heparan sulphate:heparan sulfate sulfamidase (SGSH),a-N-acetylglucosaminidase (NAGLU),heparan sulfate acetyl-CoA:a-glucosaminide N-acetyltransferase (HGSNAT),and N-acetylglucosamine-6-sulfatase (GNS).Methods:In this study,we have performed the molecular analysis of the SGSH,NAGLU and HGSNAT genes in 10 patients from 6 different MPS Ⅲ Tunisian families.Results:In the SGSH gene,two mutations were identified:one novel (p.D477N) and one already described (p.Q365X).In the NAGLU gene,two novel mutations were discovered (p.L550P and p.E153X).For the novel missense mutations found in these two genes we performed an in silico structural analysis and the results were consistent with the clinical course of the patients harboring those mutations.Finally,in HGSNAT gene,we found the splicesite mutation c.234+1G＞A that had already been reported as relatively frequent in MPS ⅢC patients from countries surrounding the basin of the Mediterranean sea.Its presence in two Tunisian MPS ⅢC families points to the hypothesis of its peri Mediterranean origin.With the exception of the c.234+1G＞A mutation,that was identified in two unrelated MPS ⅢC families,the other identified mutations were family-specific and were always found in homozygosity in the patients studied,thus reflecting the existence of consanguinity in MPS Ⅲ Tunisian families.Conclusions:Three novel mutations are reported here,further contributing to the knowledge of the molecular basis of these diseases.The results of this study will allow carrier detection in affected families and prenatal molecular diagnosis,leading to an improvement in genetic counseling.     

黏多糖贮积症Ⅰ型二例基因突变检测及产前诊断

目的 对黏多糖贮积症Ⅰ型病例进行基因检测,对再孕母亲进行产前诊断.方法 用酶学检测方法 确诊2例黏多糖贮积症Ⅰ型先证者;采用PCR扩增技术结合序列分析的方法,检测2例先证者血液及其再孕母亲羊水细胞中IDUA基因外显子及其两侧内含子.结果 在2例经酶学检测确诊的先证者中共检测出4种基因突变:p.L238R、c.883InsC、c.531InsT、p.L346R,2种为插入突变,2种为错义突变.在先证者1母亲羊水细胞IDUA基因中未发现致病基因突变,羊水细胞中IDUA酶活性为9.0 nmol/(h·mg蛋白);在先证者2母亲羊水细胞IDUA基因中检测到与先证者相同的两个致病突变,羊水细胞中IDUA酶活性为0.5 mol/(h·mg蛋白).结论 从黏多糖贮积症Ⅰ型先证者发现的4种突变中,p.L346R为已知突变,p.L238R,c.883InsC,c.531InsT为首次发现的新突变.胎儿1未获得与先证者相同致病基因,为正常胎儿.胎儿2获得与先证者相同致病基因,为受累胎儿.产前基因诊断结果 与酶学产前诊断结果 相符合.

Abstract：

Objectiye Mucopolysaccharidosis type Ⅰ(MPS Ⅰ; MIM# 252800)is an autosomal recessive disease that results from the deficiency in the lysosomal enzyme α-L-iduronidase(IDUA).IDUA is one of the enzymes involved in degradation of glycosaminoglycans heparan sulphate and dermatan sulphate.The deficiency of IDUA leads to widespread accumulation of partially degraded mucopolysaccharides inside lysosomes,resulting in progressive cellular and multiorgan dysfunction. Up to now there is no definitely effective treatment for this disorder,therefore it is important to provide an accurate genetic diagnosis and prenatal diagnosis for the MPS Ⅰ families.This study was conducted to detect IDUA gene mutation in patients with MPS Ⅰ and make a definite diagnosis of homozygote or heterozygote and make first trimester prenatal diagnosis.Method The 2 male probands included in this study were diagnosed as MPS Ⅰ patients in Peking Union Medical College Hospital,case 1 was 2 years old and case 2 was 5 years old.Genomic DNA was extracted from leucocytes in the 2 patients and 2 mothers' cultured amniocytes.IDUA gene DNA sequence was amplified by polymerase chain reaction(PCR)and the PCR products were sequenced directly.Novel mutations were analyzed in 100 normal chromosomes.Result The genotype of case 1 was p.L238R/c.883InsC,while of case 2 was c.531InsT/p.L346R.The fetal case 1 did not inherit the same pathogenic inherited the same pathogenic mutations with the proband,the genotype of fetal 2 was c.531InsT/p.L346R,in 2 MPS Ⅰ patients,p.L238R,c.883InsC,c.531InsT were novel.The fetal case 1 was diagnosed as normal fetus while the fetus 2 was diagnosed as affected.The results of the two kinds of prenatal diagnostic methods were correspondent with each other.     

Mucopolysaccharidosis type I in Morocco: clinical features and genetic profile]

BACKGROUND: Mucopolysaccharidoses (MPS) are inherited metabolic disorders due to lysosomal enzyme deficiencies, leading to glycosaminoglycan accumulation in lysosomes of different tissues. The aim of this study was to characterize MPS types, particularly MPS I, which are difficult to differentiate by clinical features. PATIENTS AND METHODS: Over a period of three years (June 1996-May 1999), 16 Moroccan patients (3-20 years old) with MPS were investigated. Twelve of them came from the Souss region. In subjects with suspected clinical MPS I or II, the diagnosis was confirmed by biochemical investigations, which included the quantification of total glycosaminoglycans (GAGs) released in urine, their identification, and the assay of alpha-L-iduronidase activity in leucocytes. A molecular analysis was performed in parallel, to provide the genetic proof of the diagnosis. RESULTS: These 16 patients belonged to 12 families, nine of which were consanguineous (75%). Twelve patients had Hurler syndrome and three had Hurler/Scheie's syndrome; no case of Scheie's syndrome was observed. Short stature, coarse face, organomegaly, hernia, cardiac disease, mental delay and dysostosis were observed in variable degrees. We report three cases without corneal clouding. Increased total urinary GAGs, identified as dermatan sulfate and heparan sulfate by thin-layer chromatography and total deficiency of alpha-L-iduronidase activity, were noted in studied subjects. At the molecular level the P533R mutation was detected in 24 among 26 alleles studied. CONCLUSION: It is now possible to perform the screening of MPS I and II in Morocco by analysis of clinical, radiologic observations and biological investigation. The predominance of P533R mutation could permit the screening of healthy heterozygotes and genetic counselling for families of Moroccan descent.     

Molecular analysis in two siblings African patients with severe form of Hunter Syndrome: identification of a novel (p.Y54X) nonsense mutation

Hunter syndrome (or Mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder due to the deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in the accumulation of heparan and dermatan sulfates in the lysosomes. The heterogeneity of clinical phenotypes, ranging from mild-to-severe forms, is a result of different mutations in the IDS gene. We report here, a novel nonsense mutation (p.Y54X) in two siblings MPS II African patients affected with a severe form of the disease. We postulated that the p.Y54X mutation which causes a loss of the IDS region highly conserved among sulfatase enzymes, could be predicted as a severe disease-causing mutation for Hunter syndrome.     

黏多糖贮积症Ⅲ型的鉴别诊断与产前诊断

目的 建立以人工合成荧光底物测定乙酰肝素N-硫酸酯酶(SGSH),α-N-乙酰葡萄糖苷酶(NAGLU)活性的方法,应用这两种方法对黏多糖贮积症Ⅲ型中的A、B亚型(MPSⅢA和ⅢB)病例进行鉴别诊断,并对MPSⅢB高危妊娠的孕妇进行了产前诊断,同时从分子遗传学方面对MPSⅢA患儿进行了SGSH基因分析.方法 采用人工合成的荧光底物(4-甲基伞形酮-α-D-N-硫酸葡萄糖苷4-methylumbelliferyl-α-D-N-sulphoglucosaminide.Na,4-甲基伞形酮-N-乙酰-α-葡萄糖苷4-methylumbelliferyl-α-N-acetylglucosaminide)测定疑似患儿白细胞和血浆中SGSH及NAGLU活性,在收集的12例患儿中,女4例,男8例,年龄3~10岁.来自10个无相关的家庭.用MPSⅢA的患儿外周血白细胞DNA进行SGSH基因的外显子PCR扩增,并通过的序列测定确定突变位置.用绒毛或经培养的羊水细胞为检材,对MPSⅢB高危妊娠的孕妇进行产前诊断.结果 获得中国正常人白细胞中SGSH活性正常值4.4～8.1 nmot/(17 h·mg蛋白),各种组织中NAGLU活性正常值:血浆中为33.3～62.4 nmoL/(4 h·ml),绒毛组织为44.9~91.7 nmol/(17 h ·mg蛋白),经培养的羊水细胞为53.2-82.2 nmol/(17 h·mg蛋白);在12例疑似患儿中确诊了7例MPSⅢA(其中两例为同胞),5例MPS ⅢB患者(其中2例为同胞),SGSH基因分析发现6种突变类型,已知突变5种(G191R,D235N,R377C,E447K和R233X),插入突变1种(D219Wfs264X),此插入突变为新生突变.3例MPSⅢB产前诊断中,2例胎儿正常,1例胎儿受累.结论 应用荧光法测定SGSH和NAGLU酶活性是敏感、可靠、快速的方法,可用于MPSⅢA和ⅢB病例的鉴别诊断及产前诊断;SGSH基因分析方法成本低,突变检出率高,可用于MPSⅢA的诊断和产前诊断.     

Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme alpha-L-iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler-Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study. Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood-brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme α- l -iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler–Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study.
Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood–brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

21-羟化酶缺乏症患者CYP21基因点突变研究

目的 了解CYP21基因编码区的常见突变谱和突变热点,并分析基因型和表现型的关系。方法 对来自51个家庭的52例21-羟化酶缺乏症患者的全长CYP21基因分两个片断进行特异性聚合酶链反应(PCR)扩增,在此基础上进行相应的巢式PCR扩增,再根据突变的特点分别采用限制性片段长度多态性(RFLP)和扩增产生酶切位点(ACRS)的方法,检测6种突变：P30L、12g(内含子2的nt656a／c→g剪切突变)、E3△8nt(外显子3第111～113密码子的8bp缺失)、I172N、V281L和Q318X。结果 在102个等位基因中,除了27个等位基因外都能够确定基因型。最常见的突变为12g,其发生频率为31％,其次为I172N(23％),Q318x(14％),V281L(9％),P30L(3％),E3△8nt(2％),其中有2个以上复合突变的等位基因占6％。失盐型患者最常见的突变为12g(45．7％)和Q318X(26％)。单纯型最常见的突变为I172N(40．7％)和12g(18．5％)。结论 本组52例患者中,73％的等位基因突变为上述6种突变,以12g和I172N为突变热点,2种突变占54％。上述结果为进一步的遗传咨询和产前诊断服务提供了有用的信息。     

远端肾小管酸中毒患儿基因型及临床表型的相关性分析

目的对确诊的6例原发性远端肾小管酸中毒(dRTA)的病例行基因型及临床表型的相关性分析。方法对2017年11月至2019年8月确诊于华中科技大学同济医学院附属武汉儿童医院的6例dRTA患儿行病史资料采集及相关辅助检查,评估其生长发育情况,留取静脉全血进行Trio全外显子高通量测序,经全谱遗传病精准诊断云平台系统分析筛选和数据分析,对可疑突变进行Sanger测序验证,后应用蛋白预测软件进行蛋白功能预测。结果6例患儿的临床症状、体征和辅助检查均符合dRTA的诊断,均表现为生长发育落后,1例患儿出现X型腿,1例患儿出现骨质疏松。辅助检查均提示低钾血症、代谢性酸中毒、碱性尿,3例患儿出现肾脏钙质沉着,2例患儿出现肾脏结石,所有患儿的父母亲均无临床表型。1例患儿为SLC4A1基因纯合突变[c.2102(exon17)G>A,p.G701D],为既往报道的常染色体隐性遗传高频突变位点,该患儿同时合并dRTA及溶血性贫血;3例为SLC4A1基因杂合突变,均为De novo突变[c.1766(exon14)G>A,p.R589H,c.1765(exon14)C>T,p.R589C],为既往报道的常染色体显性遗传高频突变位点,确诊年龄与肾脏影像学异常存在相关性。1例为ATP6V1B1基因复合杂合突变[c.806(exon9)C>T,p.P269L;c.1153(exon12)C>A,p.P385T],均为未见文献报道的新突变位点。1例为ATP6V0A4基因纯合无义突变[c.1899C>A,p.Y633X,208],为未见文献报道的新突变位点。结论SLC4A1、ATP6V1B1、ATP6V0A4是目前已明确的dRTA的主要致病基因,其突变特点及遗传方式与临床表型相关。基因检测可以对可疑的dRTA患者行早期分子诊断,有助于临床表型的筛查及个体化治疗。     

Mutational analysis of the CYP1B1 gene in Pakistani primary congenital glaucoma patients: Identification of four known and a novel causative variant at the 3′ splice acceptor site of intron 2

Primary congenital glaucoma (PCG) causes blindness in early age. It has an autosomal recessive pattern of inheritance, hence is more prevalent in populations with frequent consanguineous marriages that occur in the Pakistani population. Mutations in the CYP1B1 gene are commonly associated with PCG. The aim of the present study was to identify genetic mutations in the CYP1B1 gene in PCG cases belonging to 38 Pakistani families. DNA was extracted using blood samples collected from all enrolled patients, their available unaffected family members and controls. Direct sequencing of the CYP1B1 gene revealed a novel 3' splice acceptor site causative variant segregating in an autosomal recessive manner in a large consanguineous family with four PCG‐affected individuals. The novel variant was not detected in 93 ethnically matched controls. Furthermore, four already reported mutations, including p.G61E, p.R355X, p.R368H, and p.R390H were also detected in patients belonging to nine different families. All identified causative variants were evaluated by computational programs, that is, SIFT, PolyPhen‐2, and MutationTaster. Pathogenicity of the novel splice site variant identified in this study was analyzed by Human Splicing Finder and MaxEntScan. Ten out of 38 families with PCG had the disease due to CYP1B1 mutations, suggesting CYP1B1 was contributing to PCG in these Pakistani patients. Identification of this novel 3' splice acceptor site variant in intron 2 is the first report for the CYP1B1 gene contributing to genetic heterogeneity of disease.     

长片段PCR-DNA测序方法在Rett综合征诊断中的应用

目的探讨利用长片段PCR—DNA测序方法检测Rett综合征（RTT）患儿MECP2基因突变的可行性及临床意义。方法对40例临床诊断的RTT患儿用盐析法从外周血提取基因组DNA,采用长片段PCR同时扩增MECP2基因的第3和第4外显子,用1．5％的琼脂糖凝胶鉴定扩增目的片段的大小,进行DNA直接测序。结果在40例RTT患儿中有33例患儿MECP2基因存在突变：无义突变16例;错义突变14例;缺失突变3例,其中有一例为314bp的大片段基因缺失。突变以p．T158M最为多见,占21％（7／33）,其后依次为p．R255X,占12％（4／33）,p．R168X和p．R106W各占9％（3／33）,p．R270X和p．Y141X各占6％（2／33）,p．R133C、p．D156H、p．F157L、p．P225R、p．Q244X、p．Q262X、p．R294X、p．R306C、P322L、c．1005delG、c．1005—1318del314bp和c．1127—1179del53bp各占3％（1／33）。结论长片段PCR方法鉴定了83％（33／40）的RTT患儿存在MECP2基因突变,目前是一种简单、方便、快速、准确的基因诊断方法,能同时发现常见突变和基因大片段的缺失,有助于RTT的诊断。     

先天性甲状腺功能减低症患儿DUOXA2基因突变研究

目的 探讨广州地区先天性甲状腺功能减低症(CH)患儿DUOXA2基因突变特点及其基因型与表型的关系。方法 采用PCR及直接测序法,对2011年至2012年出生、广州市新生儿筛查中心诊断并排除DUOX2基因突变的20例疑似甲状腺激素合成障碍的CH患者进行DUOXA2基因突变分析。结果 20例CH患者中2例为p.Y246X/p.Y246X纯合突变;4例为单等位基因杂合突变:分别为已知致病突变c.413-414ins A携带者2例,p.Y246X携带者1例,新突变p.G79R携带者1例。2~3岁再评估时显示,2例p.Y246X/p.Y246X纯合突变者分别表现为暂时性CH及轻度永久性CH;4例单等位基因突变者,除1例p.Y246X携带者表现为典型永久性CH外,其余3例携带者均为暂时性CH。结论 DUOXA2基因突变是广州地区疑似甲状腺激素合成障碍性CH患儿较常见的分子发病基础,多数表现为暂时性CH,未发现DUOXA2基因型与表型的关系。新突变p.G79R为致病性突变的可能性大。     

白质消融性白质脑病患儿12例临床与遗传学研究

目的对临床诊断为白质消融性白质脑病(VWM)的中国患儿进行真核细胞翻译启动因子2Bα-ε(eIF2Bα-ε)的相应编码基因(EIF2B1～5)突变分析,以期提高儿科医生对该病的认识。方法选择临床诊断为VWM的患儿为研究对象,分析其临床特征;进行EIF2B1～5基因突变筛查;对新发现的EIF2B5基因突变,在HEK293细胞中进行突变蛋白表达水平分析。结果2006至2008年在北京大学第一医院儿科临床诊断VWM患儿12例,其中男8例,女4例。发病前智力、运动发育正常或轻度落后;起病年龄为1岁6个月至6岁8个月,均亚急性起病,起病症状多为运动功能障碍。随访至2009年6月,病程为9个月至7年。均为病情进展性加重病程,其中7例伴发作性病情加重。头颅MRI检查均提示对称性大脑白质液化特征。共发现EIF2B5,EIF2B3和EIF2B2的16种突变,其中包括9种新突变:7种错义突变为EIF2B5:c.185AT(p.D62V),c.1004GC(p.C335S),c.1126AG(p.N376D);EIF2B3:c.140GA(p.G47E),c.1037TC(p.I346T);EIF2B2:c.254TA(p.V85E),c.922GA(p.V308M);1种无义突变为EIF2B5:c.805CT(R269X);1种缺失突变为EIF2B5:c.1827-1838del(p.S610-D613del)。其中EIF2B3突变占所有突变的18.8%(3/16)。蛋白表达水平分析发现EIF2B5基因的p.R296X和p.S610-D613del突变导致eIF2Bε的蛋白表达水平显著降低。结论12例患儿均符合VWM早期儿童型诊断,发现了9种EIF2B1～5的新突变,提示中国VWM患儿具有独特突变谱。新发现的EIF2B5p.R296X和p.S610-D613del突变可导致蛋白功能严重受损。     

Glycogen storage disease type Ia: recent experience with mutation analysis, a summary of mutations reported in the literature and a newly developed diagnostic flowchart

We studied the glucose-6-phosphatase (G6Pase) gene of 30 unrelated glycogen storage disease type Ia (GSD Ia) patients using single strand conformational polymorphism (SSCP) prior to automated sequencing of exons revealing an aberrant SSCP pattern. In all patients we could identify mutations on both alleles of the G6Pase gene, indicating that this method is a reliable procedure. A total of 14 different mutations were identified. R83C (16/60), 158delC (12/60), Q347X (7/60), R170X (6/60) and ΔF327 (4/60) were found most frequently. Nine other mutations accounted for the other 15 mutant alleles. Two DNA-based prenatal diagnoses were performed successfully. At present, 56 mutations in the G6Pase gene have been reported in 300 unrelated GSD Ia patients and an overview of these mutations is presented. Evidence for a clear genotype-phenotype correlation could be established neither from our data nor from those in the literature. With increased knowledge about the genetic basis of GSD Ia and GSD Ib and the high detection rate of mutations, it is our opinion that the diagnoses GSD Ia and GSD Ib can usually be based on clinical and biochemical abnormalities combined with mutation analysis instead of enzyme assays in liver tissue obtained by biopsy. A newly developed flowchart for the diagnosis of GSD I is presented. Conclusion Increased knowledge of the genetic basis of glycogen storage disease type I provides a DNA-based diagnosis, prenatal DNA-based diagnosis in chorionic villus samples and carrier detection. Received: 6 September 1999 and in revised form: 29 October 1999 / Accepted: 29 October 1999     

肉碱棕榈酰转移酶Ⅱ缺乏症家系CPT2基因突变分析及产前诊断

分析肉碱棕榈酰转移酶Ⅱ（CPTⅡ）缺乏症患儿及其父母CPT2基因突变类型,为家系成员提供遗传咨询及产前诊断。先证者,女,于3个月时发烧8 h入院,血液酯酰肉碱谱分析显示棕榈酰肉碱显著增高,提示CPTⅡ缺乏症。收集患儿临床资料,采集患儿和父母外周血,提取基因组DNA,应用直接测序法进行CPT2基因5个外显子编码区及与外显子交界的部分内含子区域进行测序。患儿母亲于妊娠中期采取羊水,分取羊水细胞进行CPT2基因突变分析。Sanger测序发现先证者CPT2基因存在两个已知致病突变c.886C > T（p.R296X）和c.1148T > A（p.F383Y）,突变来自父母双方。母亲第二胎羊水细胞CPT2基因存在c.886C > T（p.R296X）,为致病基因携带者。胎儿出生后血液酯酰肉碱谱正常,发育正常。通过家系CPT2基因分析,证实了先证者死因为CPTⅡ缺乏症,在突变明确的前提下,成功地进行了下一胎同胞的产前诊断,为该家庭提供帮助。     

黏多糖贮积症Ⅱ型一家系IDS基因分析及产前诊断

目的 确定黏多糖贮积症Ⅱ型(Mucopolysaccharidosis type Ⅱ,MPS Ⅱ)一家系的致病基因突变,并对高危胎儿进行产前诊断.方法 应用聚合酶链反应和直接测序的方法,对先证者、胎儿及部分家系成员艾杜糖-2-硫酸酯酶(iduronate-2-sulfatase,IDS)基因的所有外显子及其与内含子交界处序列进行检测;对测序发现的性质未知的碱基改变采用高效液相色谱技术(denatruring high-performance liquid chromatography,DHPLC)在正常人群中进行筛查.结果 检测到先证者IDS基因3个碱基改变:5号外显子c.684A>G,6号外显子c.851C>T,7号外显子c.892C>T;先证者母亲和外祖母的IDS基因存在c.684A>G杂合改变,c.851C>T杂合改变及c.892C>T杂合改变;100例家系外正常男性未发现IDS基因5号外显子c.684A>G和6号外显子c.851C>T的碱基改变;胎儿基因型与先证者相同.结论 IDS基因c.892C>T突变是该MPS Ⅱ患者的主要致病原因;产前诊断证明胎儿为男性患病胎儿.     

Biochemical and molecular analysis of mucopolysaccharidoses in Turkey

The mucopolysaccharidoses (MPSs) are a family of heritable disorders caused by deficiency of lysosomal enzymes needed to degrade glycosaminoglycans (GAGs). The undegraded or partially degraded GAGs are stored in lysosomes and/or excreted in urine. In our study, 118 patients seen over the past 20 years and suspected to have lysosomal storage disorders (LSDs) were subjected to clinical and biochemical analysis at Hacettepe University Children's Hospital. We analyzed urine and blood samples from 42 patients given a clinical MPS diagnosis. Using urine screening technique, we were able to show that 34 of the 42 patients had MPS condition. Further analysis of eight patients with normal urine MPS patterns revealed four patients as likely to have alpha-mannosidosis, fucosidosis, sialidosis, and aspartylglucosaminuria (one each). Four patients had normal oligosaccharide patterns. We were able to clearly identify 4 MPS I, 2 MPS II, 5 MPS IIIA, 8 MPS IIIB, 11 MPS IVA, 3 MPS VI, and 1 MPS IIIC patients. These results provided biochemical diagnosis for these 34 patients, and clearly show that Turkey has a higher incidence of MPS IVA, IIIB, and IIIA than of previously suspected MPS types. Molecular analysis of four MPS I patients revealed three polymorphisms which have been previously reported (A314, T388, and A461T). In MPS II patients, mutation analysis identified one previously detected (R172X) and one novel mutation (W109C).     

新疆维吾尔族儿童21-羟化酶缺乏症基因型与表型的研究

目的 探讨新疆维吾尔族儿童21-羟化酶缺乏症(21-OHD)基因突变规律及基因型和临床表型的关系。方法 选取2013年10月至2014年10月就诊的20例维吾尔族21-OHD患儿为研究对象,联合应用全长直接测序法和多重连接依赖探针扩增技术检测21-羟化酶编码基因CYP21A2的突变类型,并按照基因突变类型将21-OHD患者分成不同的组别,比较预期的临床表型和实际临床表型的一致性。结果 20例患儿共发现9种突变,其中8种为已确定的致病突变,分别为Del、conv、I2g、I172N、Cluster E6、8-bp del、V281L、R356W,另1种突变为内含子5上的新发突变(c.648+37A>G),目前尚未有相关文献报道,暂不明确是否具有病理性意义。大部分根据基因突变类型预测的临床表型与实际的临床表型符合率较高(67%以上),根据P30L、V281L突变预测的临床表型与实际临床表型符合率较低(33%)。结论 21-OHD的基因型与表型有较好的相关性,通过检测患者的基因型可以预测疾病的临床表型;新发突变(c.648+37A>G)可能与21-OHD的发病有一定的关系。