Denys-Drash综合征及其致病基因突变鉴定二例报道

目的 研究中国Denys-Drash综合征(DDS)患者Wilms瘤基因1(WT1)的基因突变。 方法 应用PCR方法扩增出WT1基因全部10个外显子及其相邻内含子序列，经纯化后进行PCR产物直接测序。 结果 2例患者WT1基因分别存在1个杂合错义突变。例1的X外显子9第1180位碱基C→T突变，造成第394位精氨酸改变为色氨酸，即p.R394W(c.1180C>T)。例号2的S外显子9第1203位碱基C→A突变，造成第401位组氨酸改变为谷氨酰胺，即p.H401Q(c.1203C>A)。其中第1203位碱基C→A突变，p.H401Q (c.1203C>A)，在国内外文献及突变数据库中均未见报道，属新发现的突变。 结论 DDS综合征WT1基因中外显子9为突变热点，并发现一种新的WT1基因突变。     

Clinical features and an atypical WT1 mutant site in a child with incomplete Denys-Drash syndrome

Dear Editor, Denys-Drash syndrome （DDS） is characterized by the triad of progressive nephropathy, urogenital malformation and Wilms＇ tumor. Incomplete variants present with nephropathy with either intersex disorders or Wilms＇ tumor.1 Most DDS patients carry WTI mutations in exon 8 or 9.1 Here, we report an incomplete DDS child who carried a novel WT1 missense mutation in exon 6 and had unique clinical manifestations.     

Pulmonary dysplasia, Denys-Drash syndrome and Wilms tumor 1 gene mutation in twins

While a genetic basis for the association of developmental lung and kidney defects has been suspected, the involvement of specific genes in this process is under active investigation. We report such a possible genetic linkage present in identical twins with a mutant Wilms tumor (WT1) gene. Twin girls, born at 35 weeks gestation, manifested symptoms of congenital nephrotic syndrome, renal failure, and severe respiratory abnormalities refractory to assisted ventilation. Both died at 1 month of age. Renal biopsies and autopsy kidney tissue from both the girls revealed diffuse mesangial sclerosis (DMS). Autopsy lung tissue revealed pulmonary dysplasia and hypoplasia in both twins. The WT1 gene from renal tissue in both twins was analyzed for mutations using polymerase chain reaction (PCR) amplification and the single-strand conformation polymorphism (SSCP) technique. Both twins possessed an identical missense mutation in exon 8 of the WT1 gene, resulting in replacement of arginine by histidine at amino acid 366 (arg366his) in the WT1 protein. This mutation has previously been described in Denys-Drash syndrome. The WT1 gene plays a role in mesenchymal epithelial (ME) interactions in the developing urogenital system, and possibly has a similar role during lung morphogenesis. We propose that this WT1 gene mutation contributes to both DMS and developmental pulmonary abnormalities by altering ME interactions in both organs. Received: 13 June 2000 / Revised: 1 November 2000 / Accepted: 2 November 2000     

Novel WT1 mutation (C388Y) in a female child with Denys-Drash syndrome

We report the identification of a novel Wilms tumor suppressor gene mutation in a 5-month-old girl who presented with unilateral Wilms tumor (WT) and renal diffuse mesangial sclerosis typical of Denys-Drash syndrome (DDS). The patient did not have ambiguous genitalia and the karyotype (by amniocentesis) was 46, XX. A de novo constitutional heterozygous mutation in WT1 gene exon 9 coding for the third zinc-finger (1163G→A, C388Y) was identified. This mutation affects a cysteine residue involved in the coordination of the zinc atom, confirming the importance of these residues in the biological function of WT1 protein. Received: 10 November 2000 / Revised: 26 March 2001 / Accepted: 29 March 2001     

Clinical pictures and novel mutations of WT1-associated Denys-Drash syndrome in two Chinese children

Denys-Drash syndrome (DDS) is characterized by early onset of nephropathy, genitalia malformation, and Wilms' tumor, where WT1 is the gene that is mutated in most patients. We report two de novo mutations in WT1 found in two Chinese DDS children. Patient 1 was a boy with complete DDS who was presented with progressive nephropathy, unilateral Wilms' tumor, bilateral cryptorchidism, and renal histology showing diffuse mesangial sclerosis (DMS). When the patient was 24 months old, a liver ultrasound showed multiple nodules, and the patient died of pneumonia 1 month later. The de novo novel mutation, c.1130A>T (p.His377Leu), was identified; the mutation replaces histidine with leucine in the zinc finger (Znf) structure and is predicted to change the local spatial structure of the protein. Patient 2 had 46 XX with incomplete DDS and presented with normal genitalia, proteinuria, unilateral Wilms' tumor with renal pedicle lymph node metastasis, and renal histology showing DMS. Her renal function remains normal after 48 months. A de novo mutation, c.1168C>T (p.Arg390Term), was identified; it truncates 60 amino acids at the C terminus, and it is predicted to result in loss of the DNA-binding capacities of the WT1 protein.     

Aberrant proteoglycan composition of the glomerular basement membrane in a patient with Denys-Drash syndrome

BACKGROUND: To ascertain whether changes in proteo-glycans are involvedin the pathogenesis of the nephrotic syndrome in Denys—Drashsyndrome (DDS), we analysed the glycosaminoglycan (GAG) contentand composition of the glomerular basement membrane (GBM) inone child with this disorder and in children of comparable agewho had died from unrelated disorders. METHODS: The diagnosis of DDS was confirmed by the presence of a previouslydescribed mutation in the WT1 gene (a tumour suppressor gene).The GAG content and composition of the GBM and tubular basementmembrane (TBM), both in the Denys-Drash patient as well as age-matchedcontrol infants, was analysed by biochemical studies and indirectimmuno-fiuorescence studies. Finally we investigated the urinaryGAG excretion of the Drash patient. RESULTS: The biochemical studies revealed that the total GAG contentin the GBM as well as TBM was comparable in the Drash patientand the control group. However, the GAG composition of the GBMof the patient was clearly different, with relatively more chondroitinsulphate. The urinary GAG content (expressed as mg GAG/mmolcreatinine) was elevated in the Denys—Drash patient dueto an increased heparan sulphate (HS(GAG)) excretion. Indirectimmunofluo-rescence (IF) studies for the core protein of humanGBM heparan sulphate proteoglycan (HSPG) showed a similar linearstaining of all renal basement membranes in the patient andthe controls. A monoclonal antibody directed against the HSchain of HSPG (MoAb 403) displayed a strong GBM and a weak TBMstaining of normal kidneys. Kidney tissue from the Drash patientdisplayed a reduced staining of the GBM with MoAb 403. IF studiesfor chondroitin sulphate proteoglycan (CSPG) showed increasedstaining of the mesangium and glomerular capillary loops inthe Denys—Drash patient which is in agreement with thebiochemical studies. No discernible differences in distributionor quality of staining with antibodies against collagen typeIV and laminin were observed. CONCLUSIONS: These biochemical and immunohisto-chemical results indicatethat in our patient the proteoglycan composition of the GBMis altered. This alteration may play a role in the pathogenesisof proteinuria in this syndrome.     

A case of nephrotic syndrome with glomerular lipoprotein deposition with capillary ballooning and mesangiolysis

A 33-year-old man with nephrotic syndrome and rapid deterioration of renal function showed curious glomerular morphological abnormalities. Ballooning of the glomerular capillaries due to a substance accumulated in the capillary lumina and mesangiolysis were prominent histological features. The deposits in the capillary lumen were positive for Sudan III staining, and also for beta-lipoprotein, apoprotein B and apoprotein E by immunofluorescent technique. The staining of beta-lipoprotein in a flower leaf pattern was a striking characteristic, while such staining was negative when studied in 20 patients with nephrotic syndrome who were used as controls. Based on these findings, the morphological abnormalities in this case were considered to be related to lipoprotein deposition in the glomeruli. This case is thought to be the first reported in a complete form in the literature which could be classified as a new kind of disease related to lipoprotein metabolism abnormalities.     

Renal transplantation in the management of bilateral Wilms' tumour (BWT) and of Denys-Drash syndrome (DDS)

Background: Wilms' tumour (WT) occurs bilaterally in 5-7% of affected children. In some patients, complete surgical removal of the malignant tissue cannot be achieved without bilateral total nephrectomy. In Denys-Drash syndrome (DDS), bilateral nephrectomy is indicated both because of the associated nephropathy usually progressing rapidly to end-stage renal failure and because of the high risk of WT development in any residual renal tissue. Methods: Case records of patients with a diagnosis of either bilateral WT (BWT) or DDS, who underwent bilateral nephrectomy and subsequent renal transplantation between 1980 and 1996 at the Hospital for Sick Children, London, were reviewed. Results: Allogeneic renal transplantation was preformed in two children with BWT and four with DDS, three of whom had developed unilateral WT by the time their kidneys were removed. Renal transplantation was performed 15-49 months after bilateral nephrectomy at a mean age of 45 (26-76) months, with a minimum of 1 year tumour-free survival after completion of chemotherapy in those with WT. One patient died after renal transplantation. Five children had a favourable outcome, with a mean follow-up of 80 (29-121) months post-renal transplantation. Conclusion: Advances in dialysis and transplantation programmes for young children offer the potential for a marked improvement in the prognosis for patients with BWT and for those with DDS.     

The nephropathy associated with male pseudohermaphroditism and Wilms' tumor (Drash syndrome): a distinctive glomerular lesion--report of 10 cases

We report on 10 children, less than 2 years of age, who presented with a genuine type of glomerulopathy: diffuse mesangial sclerosis. In 5, the nephropathy was associated with male pseudohermaphroditism (MPH) and Wilms' tumor (WT); in 3 with MPH and in 2 with WT. The nephropathy was characterized by its very early onset, between the age of 2 weeks and 18 months. Eight patients presented with a nephrotic syndrome with (7 cases) or without (1 case) hypertension. All, but one, who is in advanced RF at 11 years of age, progressed to chronic or end-stage renal failure (ESRF) within a few months to 2 years from the onset. One additional child presented with advanced renal failure at the age of 8 months and the last one, who was hypertensive, developed an anuria related to thrombosis of renal veins at 1 year of age. Drash syndrome is characterized by the association of a "nephron disorder" with MPH and WT. We propose, on the basis of our histological findings, to extend the concept of Drash syndrome to patients who, in addition to the nephropathy, have either WT or MPH and to consider the distinctive glomerular lesions presented by all these patients as their common denominator. The pathogenesis of this glomerulopathy is obscure. Its early onset, its association with a dysembryoplastic tumor and/or with gonadal dysgenesis both suggest an antenatal dysgenetic process.     

A novel mutation of<Emphasis Type="Italic"> WT1</Emphasis> exon 9 in a patient with Denys-Drash syndrome and pyloric stenosis

We report a novel mutation in WT1 exon 9 (1214 A>G) resulting in an amino acid change from H to R at codon 405 in a 46 XY female patient who had congenital hypertrophic pyloric stenosis, pseudohermaphroditism masculinus, renal failure, and Wilms tumor, and died at the age of 22 months. The patient demonstrated the difficulty in diagnosing a patient with intersex before conclusive genetic characterization.     

基因启动区异常甲基化导致肝癌中RASSF1A基因外失活的研究

目的观察肝癌组织中的抑癌基因RASSF1A的表达情况和由于启动区异常甲基化导致其基因外失活的状况，并分析DNA异常甲基化与肝癌临床相关因素之间的关系。方法利用RT—PCR和MS-PCR的方法，结合DNA测序和Taq I酶切消化法，分析了24例肝癌标本、4株肝癌细胞株（SMMC7721、HepG2、BEL7402和BEL7703）中RASSF1A基因的表达情况，以及其基因启动区异常甲基化的情况。采用甲基化抑制剂5＇-Aza—CdR处理肝癌细胞株，观察RASSF1A重新表达的情况。结果66．7％的肝癌组织未表达RASSF1A；4株肝癌细胞株中仅SMMC7721检测到RASSF1A的表达。83．3％的肝癌组织及4株肝癌细胞株都发生了异常甲基化，而正常肝组织和正常肝细胞株（L02）中却未发现甲基化。甲基化与肝硬化、乙肝表面抗原、肿瘤分化程度及血管浸润和远处转移有相关性。原来RASSF1A表达失活的3株肝癌细胞株经甲基化抑制剂5＇-Aza—CdR处理后，又重新恢复了表达。结论基因转录启动区的异常甲基化是导致肝癌中RASSF1A表达失活的主要原因。检测RASSF1A启动区异常甲基化可作为一种有潜在应用价值的生物分子指标来用于肝癌的早期发现和早期诊断，以及预后的判断。