薄基底膜肾病并发局灶节段性肾小球硬化症一家系的COL4A3和COL4A4基因突变分析

目的 探讨薄基底膜肾病(TBMN)合并局灶节段性肾小球硬化症(FSGS)的遗传学机制.方法 对一病理学诊断为TBMN合并FSGS患者及其家系的COL4A3和COL4A4基因突变,应用与COL4A3和COL4A4基因连锁的微卫星标记连锁分析方法进行分析.PCR扩增COIAA3和COL4A4全部98个外显子后,直接测序筛查突变.同时测序排除已为公认的FSGS相关基因NPHS1、NPHS2、WT1、TRPC6、ACTN4、CD2AP突变导致FSGS的可能.结果 微卫星标记连锁分析显示此家系与COL4A3和COL4A4基因连锁.直接测序在此家系中发现疾病患者COL4A4基因1214位的鸟嘌呤突变为腺嘌呤,导致Ⅳ型胶原α4链第405位甘氨酸突变为谷氨酸,并且发现COL4A3基因一多态性IVS1-4C＞T.此多态性随疾病分布,可能与致病相关.未发现FSGS相关基因的突变.结论 此家系是在TBMN的基础上发生FSGS.Ⅳ型胶原α4链突变及随疾病分布的基因多态性是否导致TBMN合并FSGS或使其易感性增加尚待更多家系进一步研究.     

一例女性Fabry病并发薄基底膜肾病及其家系调查

目的 了解具有两种遗传性疾病,即Fabry病并发薄基底膜肾病（TBMN）的临床病理和基因突变特点以及家系患病情况。 方法 总结分析本院收治的1例41岁女性Fabry病并发TBMN患者的临床病理特征和基因突变情况,同时对家系成员进行调查及相关检测。 结果 先证者呈现典型的Fabry病的肾外临床表现,包括皮疹、神经痛、眩晕、耳鸣、肥厚型心肌病等,同时亦有蛋白尿、镜下血尿及高血压等肾脏受累表现;肾活检光镜下病理改变为局灶性节段性肾小球硬化（FSGS）,部分足细胞空泡变性;电镜下肾小球脏层上皮细胞胞质内多数髓磷脂小体形成,肾小球基底膜（GBM）弥漫性变薄,厚度为（216±31） nm。家系调查及基因突变检测显示先证者女儿除有典型Fabry病肾外表现外,亦有以血尿为主的肾脏症状。先证者的1个妹妹仅表现为镜下血尿。先证者及其女儿α-半乳糖苷酶 A（α-Gal A）活性分别为33和75活性单位（正常参考值为100~500活性单位）,且2人均携带新发现的GLA基因突变——1208ins21 bp及COL4A3基因多态性——c:3627 G>A（p:M1209I）。仅表现为镜下血尿的先证者的妹妹仅携带COL4A3基因的c:3627 G>A（p:M1209I）多态性,α-Gal A活性正常,无GLA基因突变。 结论 对于Fabry肾病患者呈现血尿,尤其是表现为家族性血尿时,应考虑并认真排除并发TBMN的可能。     

从α5(Ⅳ)链mRNA突变分析看Alport综合征基因型和表型关系

目的 检测分析x连锁型Alport综合征(AS)患者α5(Ⅳ)链mRNA及其序列并探讨其基因型与表型之间的关系。方法 提取21例X连锁型AS患者的培养的皮肤成纤维细胞总RNA，应用逆转录-聚合酶链反应(RT-PCR)扩增覆盖全部α5(Ⅳ)链编码区的mRNA，经直接测序的方法分析。同时根据cDNA序列异常位置，应用PCR和直接测序的方法从基因组DNA水平分析CO[4A5基因。结果 21例患者的mRNA分析均发现α5(Ⅳ)链序列异常，其中17个突变为新发现的突变。15例患者在mRNA水平检测到的结果与在基因组DNA检测到的结果一致；6例患者因发生剪接位点突变，在tuRNA水平和基因组DNA水平检测到的COL4A5基因突变不一致。16／21例患者属于青少年型AS，2／21例属于成年型AS。结论 各种类型的COL4A5基因突变均可导致严重的临床表型．而且从mRNA水平分析AS基因型，可以发现并证实一些在基因组DNA水平无法发现和证实的异常。     

杂合突变型COL4A5基因表达与Alport综合征女性表型关系分析

目的 探讨编码基因COL4A5 mRNA的表达与X连锁Alport综合征(XLAS)女性临床表型之间的关系。方法 以已确诊其COL4A5为缺失突变的女性为研究对象，以其皮肤成纤维细胞中α5(Ⅳ)链的突变mRNA表达量占总mRNA表达量(即突变mRNA表达量与正常mRNA表达量之和)的50％为界分组，并结合临床资料分析。结果 各患者均有持续性镜下血尿，突变mRNA表达多于正常mRNA表达的患者还常有肉眼血尿，而且伴有程度较重的蛋白尿：而突变mRNA表达少于或等于正常mRNA表达的患者常无肉眼血尿。而且不伴有蛋白尿或者蛋白尿的程度轻微。各患者的蛋白尿程度与其α5(Ⅳ)链的突变mRNA与总mRNA之比呈直线相关，有显著统计学意义。结论 突变COL4A5基因mRNA表达量的差异可能是影响XLAS女性临床表型的因素之一，突变等位基因mRNA的表达量居多的XLAS女性临床症状相对重。     

COL4A5基因多态性与汉族人薄基底膜肾病的关系

目的探讨薄基底膜肾病COL4A5基因突变情况,为其诊断及遗传咨询提供理论基 础。方法使用聚合酶链反应-单链构象多态性分析(PCR-SSCP)的方法,对39例薄基底膜肾病(TBMN)患者COL4A5基因的51个外显子进行分析,对SSCP发现异常者测序。结果8例患者同时发现3个同义突变和1个错义突变,即1297G-C(365Gly-Gly)、1533T-G(444Ile-Ser)、3715A-G(1171Gln-Gln)及4477C-T(1425Asp-Asp)。该4个突变构成一个单体型,在本组TBMN患者中的基因频率为11％(8/70),而正常对照中该单体型的发现率为9％(9/100)。其中1例患者还合并2417C-G(739Pro-Ala)。结论我们研究发现的单体型为正常汉族人COL4A5基因的多态性;该多态性合并其他的基因突变可能与薄基底膜肾病发病有关。     

Alport综合征患者肾组织层粘连蛋白α2链异常分布

目的 观察Alport综合征(AS)患者肾组织层粘连蛋白α2链、α5链和γ1链的分布。方法 采用免疫荧光方法,运用普通荧光和激光共聚焦扫描显微镜观察抗层粘连蛋白α2链、α5链和γ1链单克隆抗体在肾组织中的沉积情况。肾组织标本来自11例AS患者,其中男8例,女3例,年龄11~52岁。10例患者符合X伴性显性遗传(XLAS),1例女性患者符合显性遗传。8例男性XLAS患者肾小球基底膜(GBM)、远端肾小管基底膜均无Ⅳ型胶原α3、5链沉积,表皮基底膜(EBM)无α5(Ⅳ)链沉积;2例女性XLAS患者肾组织α3、5(Ⅳ)链和EBM α5(Ⅳ)链均呈不连续表达,另1例女性患者则同正常肾组织。正常人肾组织标本作为正常对照,9例IgA肾病(IgAN)、6例局灶节段硬化性肾小球病(FSGS)、5例薄基膜病(TBMD)和6例肾小球轻微病变(GML)患者作为疾病对照。结果 正常人肾组织层粘连蛋白α2链主要沉积于肾小球系膜区,层连蛋白α5、γ1链沉积于GBM、所有肾小管基底膜和入球小动脉基底膜。10例XLAS和1例显性遗传AS患者肾组织除了肾小球系膜区外,层粘连蛋白α2链在GBM上亦出现表达。IgAN、TBMD和FSGS患者层粘连蛋白α2链仅在肾小球系膜区沉积。层粘连蛋白α5、γ1链在AS患者和其他肾脏病组织沉积同正常肾组织。结论 层粘连蛋白α2链在AS患者GBM出现异位表达,为继Ⅳ型胶原α链异常之后发现的又一AS基底膜成分的异常,其对于AS可能具有重要的诊断价值。     

常染色体隐性遗传Alport 综合征一家系COL4A3及COL4A4基因突变分析

目的 通过对有近亲婚配史的Alport综合征一家系Ⅳ型胶原α3和α4链的 COL4A3/COL4A4 基因分析，明确常染色体隐性遗传Alport综合征的基因突变,为该病的基因诊断和家系遗传咨询提供更为全面的理论基础｡ 方法 PCR扩增先证者DNA COL4A3/COL4A4 基因的共98个外显子，经直接测序，寻找突变位点，对有意义的突变经限制性内切酶AvaⅡ酶切在家系中分析验证｡ 结果 在该患者中共发现1个错义突变和10个序列变异｡其中在COL4A3 基因上发现一个位于42号外显子上的错义突变 G3725A,导致蛋白质Gly1242Asp的突变｡错义突变在患者中是纯合子，携带者中是杂合子，其他正常家系成员及筛查100条正常人染色体，未发现该突变｡10个序列变异为单核苷酸多态性改变｡ 结论 报道了一个国内较少见的常染色体隐性遗传Alport 综合征家系，同时经基因突变筛查发现Ⅳ型胶原α3链的一个新的致病性的基因突变｡     

常染色体显性遗传Alport综合征致病基因 COL4A4杂合剪接突变的致病性分析及基因型-表型关联分析

目的探讨常染色体显性遗传Alport综合征(autosomal dominant Alport syndrome, ADAS)致病基因COL4A4杂合剪接突变的致病机制及基因型与表型的关联, 以加深对COL4A4剪接突变的认识以及对ADAS表型异质性的理解。方法本研究为病例系列分析。从3家医院收集5个ADAS家系先证者及家系成员的临床资料。对从先证者中经全外显子组测序(whole exome sequencing, WES)发现的COL4A4杂合剪接变异, 通过RNA体内剪接或Minigene体外实验分析其对mRNA正常剪接的影响。结果在此5个ADAS家系患者中经WES发现了4个COL4A4杂合剪接变异位点。家系1、家系2、家系3和家系4中多数患者呈孤立性镜下血尿或合并微量蛋白尿, 个别患者合并显性蛋白尿、进入老年期后出现肾功能轻度减退。家系5中4例患者均呈快速肾功能进展, 于28～41岁进展至终末期肾病。家系1、家系2患者携带的c.735+3A>G和家系3患者携带的c.694-1G>C均可引起COL4A4的第12号外显子跳跃导致42 bp核苷酸框内缺失(c.694     

X连锁显性遗传Alport综合征病例报道

正Alport综合征(alport syndrome,AS)又称眼、耳、肾综合征,是以血尿、肾功能渐进性减退、神经性耳聋和晶状体异常为特征的遗传性肾小球基底膜(glomerular basement membrane,GBM)疾病。X连锁显性遗传(x-linked dominant,XL)是其最常见的遗传方式,约占85%。位于X染色体的Ⅳ型胶原蛋白α5链(collagenⅣα5,COL4A5)基因突变破坏了Ⅳ型胶原分子结构,从而影响了基底膜的稳定性。患者既可表现为终末期肾病(end stage renal disease,ESRD),又可表现为隐匿性肾炎,所以基因测序诊断尤为重要。本文报道1例通过COL4A5基因测序确诊的AS患者,对其家系成员进行了调查随访。1先证者病史资料     

薄基底膜肾病的基因突变研究进展

薄基底膜肾病(TBMN)又称良性家族性血尿(BFH),为编码Ⅳ型胶原α链的基因突变导致的一种较常见的常染色体显性遗传性肾脏疾病.其临床表现主要为单纯性镜下血尿,可合并有轻度蛋白尿,通常预后良好~([1-3]).TBMN的诊断主要依靠电镜下见到弥漫性变薄的肾小球基底膜(GBM)~([4]).国外于20世纪60年代中期由McConville~([5])首先报道此病;国内1990年由章友康~([6])首先报道.     

原发性局灶节段性肾小球硬化ACTN4和SYNPO基因启动子的突变

目的 探讨散发性原发性局灶节段性肾小球硬化（FSGS）患者中ACTN4和SYNPO基因启动子区突变的致病作用。 方法 盐析法提取82例FSGS患者外周血基因组DNA,经引物设计及PCR扩增后测序。突变位点经转录因子结合模拟软件筛选,pGL3-Basic构建表达载体与pRL-SV40质粒瞬时共转染PC12细胞,双荧光素酶法检测基因表达。检测患者父母头发DNA。免疫荧光检测患者肾组织?琢-actinin-4和synaptopodin蛋白表达。 结果 3例ACTN4基因突变分别为1－34C>T、1－590delA和（1－1044delT）+（1－797T>C）+（1－769A>G）。2例SYNPO基因突变分别为1－24G>A和1－851C>T。1例患者分别接受父母1－1044delT和 1－797T>C变异。除1－1044delT组外,变异组荧光素酶表达强度比正常组有不同程度下降,与突变患者肾组织?琢-actinin-4和synaptopodin免疫荧光强度下降基本相符。 结论 ACTN4和SYNPO基因启动子区顺式作用元件区的变异影响基因的转录,可能在散发性FSGS发病中起作用。     

Clinical and genetic characters of 8 Chinese children with ADCK4-associated glomerulopathy

Objective To investigate the clinical and genetic character of Chinese children with the aarF domain containing kinase 4 (ADCK4)-associated glomerulopathy. Methods Applying next generation sequencing to detect possible gene mutation(renal disease associated monogene was pooled as one panel) in 69 children with steroid-resistant nephrotic syndrome (SRNS) or persistent proteinuria of unknown origin. Sanger sequencing was used to confirm the significant mutations found in the children and to validate these mutation sites in their patients. Using online software (PolyPhen2, SIFT, Mutation Taster) to predict whether the detected missense mutations were disease causing or not. Collecting and analyzing clinical data of children with ADCK4-associated glomerulopathy, which included onset age, clinical manifestation, and renal pathology. Results The ADCK4 gene mutation was detected in 8 children with a positive rate of 11.6% (8 out of 69), among which 3 patients carried homozygous c.748G>C mutation, 3 patients carried homologous c.737G>A mutation, 1 patient carried compound heterozygous mutation(c.748G>C and c.737G>A), and 1 patient carried compound heterologous mutation(c.551A>G and c.737G>A). Collectively, there were only 3 mutation sites found in total 8 patients, in which the mutation sites of c.748G>C and c.737G>A had high detection frequency in these 8 patients. These 3 mutation sites were all missense mutation which were predicted to be disease causing by online software and not reported before. The average onset age was 6.5 years (2 years-11.75 years). Four patients presented with SRNS and the other 4 presented with persistent proteinuria. All 8 patients had no extrarenal manifestation, renal biopsy revealed focal segmental glomerulosclerosis (FSGS) in most patients, among which 3 cases had gone to end-stage renal disease (ESRD) at disease onset, and 2 cases progressed to ESRD 2 and 5 years after onset respectively. Seven patients had received glucocorticoid and /or immunosuppressive drug while only one patient getting partial response. All 8 patients were treated with large amount of coenzyme Q10 (15 mg?kg-1?d-1) after definite diagnosis of ADCK4 mutation-some patients had acquired encouraging curative effect. Conclusions ADCK4-associated glomerulopathy is not rare especially in the children with SRNS. The onset age is relatively old and the extrarenal manifestation is less common. FSGS is a main pathology type. Patients usually have no response to immunosuppressive therapy, but may benefit from addition of large amount of coenzyme Q10. Some patients may only manifest with insidious proteinuria, causing the early diagnosis to be difficult, which deserves more attention. Three new missense mutations expand disease causing mutation repertoire of ADCK4 gene, among which the two sites of c.748G>C and c.737G>A may be mutation hotspot of ADCK4-associated glomerulopathy in Chinese population, and need further study.     

Thin basement membrane nephropathy

Thin basement membrane nephropathy. Thin basement membrane nephropathy (TBMN) is the most common cause of persistent glomerular bleeding in children and adults, and occurs in at least 1% of the population. Most affected individuals have, in addition to the hematuria, minimal proteinuria, normal renal function, a uniformly thinned glomerular basement membrane (GBM) and a family history of hematuria. Their clinical course is usually benign. However, some adults with TBMN have proteinuria >500 mg/day or renal impairment. This is more likely in hospital-based series of biopsied patients than in the uninvestigated, but affected, family members. The cause of renal impairment in TBMN is usually not known, but may be due to secondary focal segmental glomerulosclerosis (FSGS) or immunoglobulin A (IgA) glomerulonephritis, to misdiagnosed IgA disease or X-linked Alport syndrome, or because of coincidental disease. About 40% families with TBMN have hematuria that segregates with the COL4A3/COL4A4 locus, and many COL4A3 and COL4A4 mutations have now been described. These genes are also affected in autosomal-recessive Alport syndrome, and at least some cases of TBMN represent the carrier state for this condition. Families with TBMN in whom hematuria does not segregate with the COL4A3/COL4A4 locus can be explained by de novo mutations, incomplete penetrance of hematuria, coincidental hematuria in family members without COL4A3 or COL4A4 mutations, and by a novel gene locus for TBMN. A renal biopsy is warranted in TBMN only if there are atypical features, or if IgA disease or X-linked Alport syndrome cannot be excluded clinically. In IgA disease, there is usually no family history of hematuria. X-linked Alport syndrome is much less common than TBMN and can often be identified in family members by its typical clinical features (including retinopathy), a lamellated GBM without the collagen alpha3(IV), alpha4(IV), and alpha5(IV) chains, and by gene linkage studies or the demonstration of a COL4A5 mutation. Technical difficulties in the demonstration and interpretation of COL4A3 and COL4A4 mutations mean that mutation detection is not used routinely in the diagnosis of TBMN.     

Chronic renal failure and shortened lifespan in COL4A3+/- mice: an animal model for thin basement membrane nephropathy

A heterozygous mutation in autosomal Alport genes COL4A3 and COL4A4 can be found in 20 to 50% of individuals with familial benign hematuria and diffuse glomerular basement membrane thinning (thin basement membrane nephropathy [TBMN]). Approximately 1% of humans are heterozygous carriers of mutations in the autosomal Alport genes and at risk for developing renal failure as a result of TBMN. The incidence and pathogenesis of renal failure in heterozygous COL4A3/4 mutation carriers is still unclear and was examined further in this study using COL4A3 knockout mice. In heterozygous COL4A3(+/-) mice lifespan, hematuria and renal function (serum urea and proteinuria) were monitored during a period of 3 yr, and renal tissue was examined by light and electron microscopy, immunohistochemistry, and Western blot. Lifespan of COL4A3(+/-) mice was found to be significantly shorter than in healthy controls (21.7 versus 30.3 mo). Persistent glomerular hematuria was detected starting in week 9; proteinuria of > 0.1 g/L started after 3 mo of life and increased to > 3 g/L after 24 mo. The glomerular basement membrane was significantly thinned (167 versus 200 nm in wild type) in 30-wk-old mice, coinciding with focal glomerulosclerosis, tubulointerstitial fibrosis, and increased levels of TGF-beta and connective tissue growth factor. The renal phenotype in COL4A3(+/-) mice resembled the clinical and histopathologic phenotype of human cases of TBMN with concomitant progression to chronic renal failure. Therefore, the COL4A3(+/-) mouse model will help in the understanding of the pathogenesis of TBMN in humans and in the evaluation of potential therapies.     

The R229Q mutation in <Emphasis Type="Italic">NPHS2</Emphasis> may predispose to proteinuria in thin-basement-membrane nephropathy

Thin-basement-membrane nephropathy (TBMN) is characterized by persistent dysmorphic hematuria, and the presence of proteinuria is a risk factor for renal impairment. TBMN is often due to mutations in the COL4A3 and COL4A4 genes, and this study determined whether additional mutations in genes encoding other structures in the glomerular filtration barrier contributed to the development of proteinuria. Fifty-six unrelated individuals with TBMN including 18 (32%) with proteinuria ≥ 300 mg/L and ten (18%) with proteinuria ≥ 500 mg/L were studied. Deoxyribonucleic acid (DNA) was screened for NPHS2 mutations and variants (R138Q and P375L) using single-stranded conformational analysis (SSCA) and for the R229Q mutation by sequencing. DNA was also screened for ACTN4 mutations. R229Q was more common in patients with TBMN and proteinuria ≥ 500 mg/L (p < 0.05), and a possible NPHS2 mutation (671G>A, R224H) was identified in one patient with proteinuria 700 mg/L. No other NPHS2 variants correlated with proteinuria, and no ACTN4 mutations were found. Individuals with TBMN and R229Q are carriers of the autosomal recessive forms of both Alport syndrome and familial focal segmental glomerulosclerosis (FSGS). The early demonstration of R229Q in individuals with TBMN may indicate those at increased risk of proteinuria and renal impairment.     

原发性局灶节段性肾小球硬化患者CD2AP基因突变的研究

目的了解原发性局灶节段性肾小球硬化（FSGS）患者CD2AP基因突变特点。方法研究对象为2001年至2004年我院收治的82例病理确诊为FSGS患者，年龄12-76岁，男性43例，女性39例，临床诊断为肾病综合征（NS）者55例，非NS27例；60例健康正常人为对照组。外周血基因组DNAPCR扩增后直接测序。冰冻切片免疫荧光双染色，激光共聚焦显微镜采集图像检测突变患者肾组织中CD2AP和podocin蛋白的表达。结果（1）发现2个CD2AP外显子突变，1个为2号外显子160G〉A杂合突变，造成第54位氨基酸由缬氨酸变为异亮氨酸（V54I），该患者为非NS患者，已出现肾功能不全。另1个为4号外显子358A〉G杂合突变，造成第120位氨基酸由异亮氨酸变为缬氨酸（1120V），该患者为NS患者，曾复发2次，目前肾功能尚正常。正常对照120条染色体中未发现同样突变。查阅文献和基因库，未发现相同突变报道。（2）CD2AP外显子突变患者肾小球内CD2AP表达明显减低，同时伴有podocin表达的降低。（3）发现1个启动子区突变、2个内含子突变和8个SNP位点，其中一个单核苷酸多态性（SNP）位点以往未见报道。结论CD2AP突变可能是原发性FSGS的致病原因之一。CD2AP外显子突变可导致CD2AP蛋白表达减少，并影响podocin的表达。     

Signs and symptoms of thin basement membrane nephropathy: a prospective regional study on primary glomerular disease-The Limburg Renal Registry

BACKGROUND: To chart the epidemiology of primary glomerular disease by means of a prospective regional study in the southern part of The Netherlands. METHODS: Experienced renal technicians collected renal biopsies, blood, and 24-hour urine samples at the bed site in each of the participating hospitals. The material was processed and analyzed at the University Hospital Maastricht. Analysis included light microscopy, immunohistochemistry, and electron microscopy of the biopsies as well as serologic and chemical analysis. RESULTS: Primary IgA nephropathy (IgAN), membranous glomerulopathy, antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis and thin basement membrane nephropathy (TBMN) are the most common primary glomerular diseases in this order of sequence. Our data show the clinical and histologic phenotype of TBMN to be diverse: the vast majority of TBMN has chronic microscopic hematuria, frequently associated with hypertension in late middle age; about 15% of TBMN has in addition substantial proteinuria which is associated in the majority of cases with the lesions of focal segmental glomerulosclerosis (FSGS). In 5% of TBMN a nephrotic syndrome is observed, occasionally associated with FSGS tip lesions. CONCLUSION: These results support the notion that TBMN is a disease of genetic heterogeneity; it is not a benign renal condition in a substantial number of patients, particularly those in late middle age.