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｡     

Alport综合征一家系中新的COL4A5基因突变

目的了解我国Ｘ伴性显性（ＸＤ）遗传Ａｌｐｏｒｔ综合征（ＡＳ）中ＣＯＬ４Ａ５基因突变特点。方法应用聚合酶链反应（ＰＣＲ）－变性梯度凝胶电泳（ＤＧＧＥ）和直接测序的方法，对来自７个ＸＤ－ＡＳ家系１０个成员和１００个正常人外周血ＤＮＡ标本进行了ＣＯＬ４Ａ５基因４３号外显子的检测。结果在一个家系中发现４１４２Ｃ→Ｔ（Ｐｒｏ１３１４Ｓｅｒ）的转换突变，先证者与其弟、其母均发现有此异常。结论表明该突变为一遗传     

A novel G472R mutation in a Turkish family with X-linked Alport syndrome

Alport syndrome (AS) is a hereditary disorder of progressive nephritis. Most cases are X-linked, but autosomal forms have been reported. The X-linked form is associated with mutations in the COL4A5 gene that encodes the α5 chain of type IV collagen. More than 200 mutations have been reported in X-linked AS. We report a novel 1616 G>A mutation resulting in glycine substitution to arginine at position 472 in a Turkish family with a severely affected man and several variably affected women. This is the first Turkish family in whom the molecular basis of the disease has been reported. Received: 16 December 1998 / Revised: 30 June 1999 / Accepted: 7 July 1999     

Living related kidney transplantation in a patient with autosomal-recessive Alport syndrome

Abstract:  We discuss a patient with Alport syndrome who received a renal transplant from a donor with thin basement membrane disease. A 30-year-old woman, diagnosed with Alport syndrome on the basis of sensorineural hearing loss, characteristic renal biopsy findings and a family history of microhaematuria, entered chronic haemodialysis therapy. She then received a renal transplant donated from her father, who had sensorineural hearing loss and persistent microhaematuria. On the day of renal transplantation, a 1-h graft biopsy after reperfusion showed thin basement membrane disease. We re-tested the patient's native kidney biopsy specimen by immunohistochemical staining using α-chain-specific collagen type IV monoclonal antibodies. There was no expression of collagen type IV α3-, α4- and α5-chain on glomerular basement membrane, but positive staining of α5-chain on Bowman's capsular basement membrane was noted. A diagnosis of autosomal-recessive Alport syndrome was made. We concluded that this family might display different phenotypic expressions of the same genotype: one suffered end-stage renal disease and the other thin basement membrane disease.     

Correlation of histopathological features and renal impairment in autosomal dominant Alport syndrome in Bull terriers.

BACKGROUND: Bull terrier hereditary nephritis represents a model for autosomal dominant Alport syndrome, as affected dogs have the characteristically lamellated glomerular basement membrane and demonstrate vertical male-to-male disease transmission. METHODS: This study compared the histopathological features in kidneys from affected Bull terrier neonates, puppies, and adult dogs with normal or impaired renal function, with the histopathological appearance of kidneys from age- and size-matched normal dogs. RESULTS: There were fewer glomeruli per unit area of cortex in kidneys from affected neonatal kidneys (P<0.05), increased numbers of fetal glomeruli in affected puppy kidneys (P<0.05), and a separate population of glomeruli with larger renal corpuscles and glomerular tufts in kidneys from affected adult dogs with normal renal function (both P<0.0001) compared with normal dogs. Other histological features that are characteristic of human X-linked and autosomal recessive Alport syndrome and that were present included hypercellular glomeruli, occasional crescents, segmental and global glomerular sclerosis, periglomerular fibrosis, interstitial fibrosis without significant cellular infiltrates and cystic dilatation of Bowman's capsular space and tubules. In dogs with renal impairment, the tubular index was the best predictor of increased urinary protein:creatinine (r=0.92) compared with glomerular, interstitial and vascular indices (r=0.77, 0.88 and 0.81), and medullary fibrosis correlated best with serum creatinine (r=0.72, P=0.0002). CONCLUSIONS: The demonstration in Bull terrier kidneys of fewer nephrons in neonates increased fetal glomeruli, and a separate population of glomeruli with larger corpuscles and tufts reflects the effects of the underlying genetic mutation that are first manifest antenatally. The major determinant of renal impairment in adult affected Bull terriers is, however, progressive tubulointerstitial damage after birth.     

A novel model of autosomal dominant Alport syndrome in Dalmatian dogs.

BACKGROUND: Autosomal dominant Alport syndrome is a rare inherited disease characterized clinically by haematuria, renal failure and deafness, and ultrastructurally by a lamellated glomerular basement membrane (GBM). It is usually caused by mutations in the COL4A3 or COL4A4 genes which code for the alpha3 and alpha4 chains of type IV collagen. We describe here a novel spontaneous model of autosomal dominant Alport syndrome in Dalmatian dogs. METHODS: Affected dogs were identified by a urinary protein creatinine >/=0.3. A total of 10 affected adult Dalmatians and eight unaffected age- and sex-matched dogs from breeds other than Dalmatians were examined. In addition, kidneys from five Dalmatian fetuses from affected mothers were examined histologically and ultrastructurally. RESULTS: All affected dogs were purebred Dalmatians and had a common progenitor. Successive generations were affected, and males and females were affected equally often and equally severely, consistent with autosomal dominant inheritance. The median age at onset of renal failure was 18 months (range 8 months to 7 years). Affected dogs were not clinically deaf, and did not have the ocular abnormalities seen in human X-linked or autosomal recessive Alport syndrome. In addition, they did not have the leucocyte inclusions, low platelet counts or large platelets seen in autosomal dominant hereditary nephritis due to MYH9 mutations. The renal histology and ultrastructural appearance of the GBM appeared to be normal in utero. However, affected adult kidneys demonstrated segmental glomerular hyalinosis and sclerosis with tubulo-interstitial inflammation and fibrosis, and on ultrastructural examination the GBM was lamellated with subepithelial frilling, vacuolation and occasional intramembranous deposits. All alpha1(IV)-alpha5(IV) type IV collagen chains were present in the affected GBM and Bowman's capsule. CONCLUSIONS: Autosomal dominant Alport syndrome in Dalmatians resembles the disease in Bull terriers but has arisen independently. These models will enable us to determine how genetic mutations affect the corresponding proteins and overall membrane structure in autosomal dominant Alport syndrome.     

Mutation detection of COL4An gene based on mRNA of peripheral blood lymphocytes and prenatal diagnosis of Alport syndrome in China

Aim: Alport syndrome (AS) is a progressive renal disease characterized by haematuria and progressive renal failure. An accurate genetic diagnosis of AS is very important for genetic counselling and even prenatal diagnosis. Methods: We detected mutation of COL4An by amplifying the entire coding sequence mRNA of peripheral blood lymphocytes using polymerase chain reaction (PCR) in five Chinese AS families who asked for genetic counselling and prenatal diagnosis, then performed prenatal genetic diagnosis for four families. Mutation analysis of the foetus was made using DNA extracted from amniocytes. Foetus sex was determined by PCR amplification of SRY as well as karyotype analysis. Maternal cell contamination was excluded by linkage analysis. Results: Four different COL4A5 gene variants and two COL4A3 gene variants were detected in the five families. Because there was a de novo mutation in family 2, prenatal diagnosis was performed for the other four families. Results showed a normal male foetus for family 1 and family 4, respectively. Results showed an affected male foetus for families 3 and 5, and the pregnancies were terminated. Conclusion: An easier, faster and efficacious method for COL4An gene mutation screening based on mRNA analysis from peripheral blood lymphocytes was established. Prenatal genetic diagnosis was performed in four AS families in China.     

Improved genetic counseling in Alport syndrome by new variants of COL4A5 gene

There are current requirements of using genetic databases for offering a better genetic assistance to patients of some syndromes, especially those with X‐linked heredity patterns (like Alport Syndrome) for the high probability of having descendants affected by the disease. We describe the first reported case of COL4A5 gene missense c.1499 G > T mutation in a 16‐year‐old girl confirmed to be affected by Alport Syndrome after genetic counseling. Next Generation Sequencing procedures let discover this mutation and offer an accurate clinical treatment to this patient. Current scientific understanding of genetic syndromes suggests the high importance of updated databases and the inclusion of Variant of Unknown Significance related to clinical cases. All of this updating could enable patients to have a better opportunity of diagnosis and having genetic and clinical counseling. This event is even more important in women planning to start a family to have correct genetic counseling regarding the risk posed to offspring, and allowing the decision to undergo prenatal testing.     

Characterization of the peripheral retinopathy in X-linked and autosomal recessive Alport syndrome.

BACKGROUND: Alport syndrome is an inherited disease resulting in kidney failure, hearing loss and ocular abnormalities. Alport syndrome is however often unrecognized, and the aim of this study was to characterize the associated but rarely described peripheral retinopathy and determine whether its demonstration was diagnostically helpful. METHODS: Index cases were diagnosed with Alport syndrome on renal biopsy in themselves or a family member. Inheritance and affected status were determined using microsatellite markers at the COL4A5 and COL4A3/COL4A4 loci, respectively. Participants' eyes were dilated, and examined with direct and indirect ophthalmoscopy, and slit lamp biomicroscopy by an expert ophthalmologist who was unaware of the patients' disease status. RESULTS: Ten males and nine females with X-linked Alport syndrome and seven with autosomal recessive disease were studied. Of the 26 patients, 16 had central retinopathy (62%), and 19 patients had peripheral retinopathy (74%). The peripheral changes occurred in both males and females with X-linked and autosomal recessive Alport syndrome, and were more common when renal failure, hearing loss, lenticonus and the central changes were present, but were also noted in 3 X-linked carriers with normal renal function. CONCLUSIONS: The peripheral retinopathy occurs in X-linked and autosomal recessive Alport syndrome even when the central retinopathy is absent. Careful retinal examination and photography that includes the periphery is a safe and inexpensive method that may help in the diagnosis of Alport syndrome especially in carriers of X-linked disease.     

Mutational analysis of COL4A5 gene in Korean Alport syndrome

Mutational analysis of the COL4A5 gene in X-linked Alport syndrome (AS) requires an expensive and time-consuming procedure with a detection rate of 50%, at best. There have been three multicenter collaborative studies of mutation analysis in the COL4A5 gene using systematic screening of entire coding regions of the gene. This is a similar study executed in a single center in Korea. Twenty-five unrelated Korean patients with AS in whom the diagnosis was confirmed pathologically were included in the study. By systematic screening of all 51 exons of the gene using polymerase chain reaction/single-strand conformation polymorphism analysis, ten mutations were detected in 10 unrelated patients. These included one medium-sized deletion involving exon 49–51, one single base pair deletion, one nonsense point mutation, one splice site mutation, and six missense point mutations. Of the six missense mutations, four involved a glycine residue and disrupted the Gly-X-Y repeats in the collagenous domain. The overall detection rate of mutations was 40%. Although DNA analysis in AS is currently not applicable to routine clinical diagnosis due to several practical and technical problems, it is likely to replace morphological diagnosis in the near future. Received: 22 March 1999 / Revised: 21 May 1999 / Accepted: 21 May 1999     

Clinical issues in renal transplantation in the elderly

Kidney transplantation is the best renal replacement therapy option and is superior to dialysis in elderly end‐stage renal disease (ESRD) patients. Furthermore, the outcome of transplantation in the elderly is comparable to younger patients in terms of allograft survival. The exact nature of this phenomenon is not completely clear. As the elderly population continues to grow, it becomes more important to identify specific issues associated with kidney transplantation. In particular, elderly transplant recipients might have a lower chance of acute rejection as their immune systems seem to be less reactive. This might predispose elderly recipients to greater risk of post‐transplant infectious complications or malignancies. Furthermore, due to differences in pharmacokinetics, elderly recipients might require lower doses of immunosuppressive medication. As the main cause of graft failure in the elderly is death with a functioning graft and also considering the scarcity of donor organs, it might make sense to recommend transplanting elderly recipients with extended criteria donor kidneys. This approach would balance shorter patient survival compared to younger recipients. In conclusion, old age should not preclude ESRD patients from kidney transplantation. However, specific differences that have to do with immunosuppression and other aspects of managing elderly transplant recipients should be considered.     

Simultaneous heart and kidney transplantation in patients with end-stage heart and renal failure.

Combined simultaneous organ transplantation has become more common as selection criteria for transplantation have broadened. Broadening selection criteria is secondary to improved immunosuppression and surgical techniques. The kidney is the most common extrathoracic organ to be simultaneously transplanted with the heart. A series of 13 patients suffering from both end-stage heart and renal failure underwent 14 simultaneous heart and kidney transplantations at Temple University Hospital between 1990 and 1999. This is the largest series reported from a single center. Three patients died during the initial hospitalization for an in-hospital mortality of 21%. Of 10 patients who left the hospital, 1-year survival was 100% and 2-year survival 75%. One patient required retransplant for rejection within the first year. Overall mortality at 1 and 2 years was 25 and 41%, respectively. Four out of nine (44%) patients greater than 5 years post-transplant were alive. Of the 10 patients who left the hospital, 66% were alive at 5 years. One patient succumbed to primary nonfunction of the cardiac allograft, while the four other deaths were secondary to bacterial or fungal sepsis. The patient's racial backgrounds were equally divided between African-American and white. These results are similar to those reported in a United Network of Organ Sharing Database (UNOS) registry analysis of 84 simultaneous heart and kidney transplants that found 1- and 2-year survival to be 76 and 67%, respectively. Simultaneous heart and kidney transplantation continues to be a viable option for patients suffering from failure of these two organ systems, although the results do not match those of heart transplant alone.     

Chronic renal outcome after living donor liver transplantation

Chronic kidney disease (CKD) is one of the common complications after deceased donor liver transplantation. Although the worldwide pressing shortage in deceased donors has directed attention to living donor liver transplantation (LDLT), LDLT cohort data focusing on chronic renal dysfunction is limited. A total of 280 adult LDLT recipients (median 49 yr, 156 men) at the University of Tokyo hospital between 1996 and 2006 were reviewed. A total of 224 pre‐transplant liver failure patients (80.0%) showed an estimated glomerular filtration rate (eGFR) of more than 60 mL/min/1.73 m². However, during follow‐up at a mean of 1222 d after transplantation, eGFR declined to 60 mL/min/1.73 m² and 30 mL/min/1.73 m² in 150 (53.2%) and 21 (7.5%), respectively, and four patients (1.4%) required maintenance renal replacement therapy. Multivariate Cox proportional hazard model regression analysis revealed that recipient age (HR, 3.42 per 10‐yr increment; p < 0.001) and pre‐transplant eGFR (HR, 0.85 per 10‐mL/min/1.73 m² increment; p = 0.04) were associated independently with a post‐transplant decrease in eGFR to less than 30 mL/min/1.73 m². We conclude that higher age and lower pre‐transplant eGFR of an LDLT recipient indicate a high likelihood of subsequent development of advanced CKD. Preventive or therapeutic intervention should be optimized for these high‐risk patients.     

Alport syndrome associated with diffuse leiomyomatosis: COL4A5-COL4A6 deletion associated with a mild form of Alport nephropathy.

BACKGROUND: The X-linked Alport syndrome (AS) is an inherited nephropathy due to mutations in the COL4A5 gene, encoding the alpha5 chain of type IV collagen, a major component of the glomerular basement membrane (GBM). Here, we report a new kindred with the rare association of X-linked AS and diffuse leiomyomatosis (DL), which is a tumourous process involving smooth muscle cells of the oesophagus, the tracheobronchial tree and, in females, the genital tract. For this syndrome, an almost constant association of large COL4A5 rearrangements with a severe juvenile form of nephropathy has been described for male patients. METHODS: DNA rearrangement at the COL4A5-COL4A6 locus was studied in several members of this family using polymerase chain reaction and pulsed field gel electrophoresis. Furthermore, immunohistochemical staining of tumour and skin samples was performed. RESULTS: The affected patients in this family carry a 120 kb deletion by which the COL4A5 exon 1 and COL4A6 exons 1, 1', and 2 are removed. Immunohistochemical investigation of a skin biopsy of an affected male patient confirmed the absence of both the alpha5 and the alpha6 chains of type IV collagen in the basement membrane of the skin. Surprisingly, both affected male patients had a rather mild renal phenotype. CONCLUSIONS: This report shows that, contrary to what has been reported to date, patients suffering from AS associated with DL can be associated with a late onset renal failure (adult) form of nephropathy.     

A new point mutation in the COL4A5 gene described in a Spanish family with X-linked Alport syndrome

BACKGROUND/AIM: Alport syndrome is a hereditary glomerulonephritis, X-linked in 85% of the cases. This form is associated with mutations in the COL4A5 gene which encodes the alpha5 chain of type IV collagen. We have performed the mutational analysis of the COL4A5 gene in a Spanish family with X-linked Alport syndrome. METHODS: We have analyzed three polymorphic markers close to the gene to confirm the X chromosome linkage. By means of the PCR technique, we have screened the 51 exons of the gene. RESULTS: The segregation of the alleles from the analyzed markers was in agreement with the X linkage. Direct sequencing of PCR-amplified products has shown a CCT-to-CTT change in exon 25, resulting in substitution of a proline for a leucine at position 619 of the polypeptide chain (nucleotide 2058). CONCLUSIONS: Although proline is considered a nonconserved amino acid, it is essential, upon hydroxylation, in the maintenance of a stable alpha chain triple-helix collagen. Furthermore, the change cosegregates with the disease in all affected members of the family, not being present in 80 control chromosomes. This represents a new mutation in the COL4A5 gene found in the Spanish population.     

Putative mutation of PKD1 gene responsible for autosomal dominant polycystic kidney disease in a Chinese family

Autosomal dominant polycystic kidney disease (ADPKD) is a common and severe renal disease. Mutations of PKD1 and PKD2 genes are responsible for approximately 85% and 15% of ADPKD cases, respectively. In the present study, PKD1 and PKD2 genes were analyzed in a large Chinese family with ADPKD using denaturing high‐performance liquid chromatography and DNA sequencing. A novel mutation, c.3623‐3624insGTGT in exon 15 of the PKD1 gene, was identified in all nine affected family members, but not in any unaffected consanguineous relatives or 100 unrelated controls. These findings suggest that the unique 4 bp insertion, c.3623‐3624insGTGT, in the PKD1 gene might be the pathogenic mutation responsible for the disease in this family.     

Sporadic case of X-chromosomal Alport syndrome in a consanguineous family

Alport syndrome (AS) is a genetic disorder of basement membranes caused by mutations in type IV collagen genes that is characterized by chronic hematuria and progressive nephropathy leading to renal failure. The main extrarenal features include sensorineural hearing loss and ocular lesions. The mode of inheritance is X-linked dominant in about 80%–85% of the affected families, whereas autosomal transmission is rarely encountered. We report a male patient originating from a healthy consanguineous Lebanese family who presented with an unusual association of obstructive uropathy and AS. Hematuria and proteinuria were initially attributed to a suspected poststreptococcal glomerulonephritis (GN) and high-grade subpelvic ureteral stenosis. Persistence of symptoms after medical treatment of poststreptococcal GN and surgical correction of obstructive uropathy finally led to renal biopsy. The observed ultrastructural changes of the glomerular basement membrane were typical for AS.Molecular genetic studies revealed a previously undescribed de novo mutation in the COL4A5 gene, excluding maternal heterozygotic carrier status. This case report emphasizes the importance of hereditary nephritis in the differential diagnosis of chronic hematuria, and demonstrates the value of molecular studies for genetic counselling in AS. Received: 9 October 1998 / Revised: 15 February 1999 / Accepted: 24 August 1999