The Experts below are selected from a list of 1665 Experts worldwide ranked by ideXlab platform
Edgar A Otto - One of the best experts on this subject based on the ideXlab platform.
-
Identification of 99 novel mutations in a worldwide cohort of 1,056 patients with a nephronophthisis-related ciliopathy
Human Genetics, 2013Co-Authors: Jan Halbritter, Friedhelm Hildebrandt, Daniela A. Braun, Moumita Chaki, Susan J. Allen, Jonathan D. Porath, Katrina A. Diaz, Stefan Kohl, Neveen A. Soliman, Edgar A OttoAbstract:Nephronophthisis-related ciliopathies (NPHP-RC) are autosomal-recessive cystic kidney diseases. More than 13 genes are implicated in its pathogenesis to date, accounting for only 40 % of all cases. High-throughput mutation screenings of large patient cohorts represent a powerful tool for diagnostics and identification of novel NPHP genes. We here performed a new high-throughput mutation analysis method to study 13 established NPHP genes ( NPHP1 – NPHP13 ) in a worldwide cohort of 1,056 patients diagnosed with NPHP-RC. We first applied multiplexed PCR-based amplification using Fluidigm Access-Array™ technology followed by barcoding and next-generation resequencing on an Illumina platform. As a result, we established the molecular diagnosis in 127/1,056 independent individuals (12.0 %) and identified a single heterozygous truncating mutation in an additional 31 individuals (2.9 %). Altogether, we detected 159 different mutations in 11 out of 13 different NPHP genes, 99 of which were novel. Phenotypically most remarkable were two patients with truncating mutations in INVS/NPHP2 who did not present as infants and did not exhibit extrarenal manifestations. In addition, we present the first case of Caroli disease due to mutations in WDR19/NPHP13 and the second case ever with a recessive mutation in GLIS2/NPHP7 . This study represents the most comprehensive mutation analysis in NPHP-RC patients, identifying the largest number of novel mutations in a single study worldwide.
-
clinical characterization and nphp1 mutations in nephronophthisis and associated ciliopathies a single center experience
Saudi Journal of Kidney Diseases and Transplantation, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan ElkikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P <0.01). Homozygous NPHP1 deletions were detected in six patients from five of 17 (29.4%) studied families. Our study demonstrates the clinical phenotype of NPHP and related disorders in Egyptian children. Also, we report that homozygous NPHP1 deletions account for 29.4% of NPHP in the studied families in this cohort, thereby confirming the diagnosis of type-1 NPHP. Moreover, our findings confirm that NPHP1 deletions can indeed be responsible for JSRD.
-
Clinical characterization and NPHP1 mutations in nephronophthisis and associated ciliopathies: a single center experience.
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation Saudi Arabia, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan El-kikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P
-
Genotype–phenotype correlation in 440 patients with NPHP-related ciliopathies
Kidney international, 2011Co-Authors: Moumita Chaki, Julia Hoefele, Edgar A Otto, Gokul Ramaswami, Susan J. Allen, Sabine Janssen, Carsten Bergmann, John R. Heckenlively, Friedhelm HildebrandtAbstract:Nephronophthisis (NPHP), an autosomal recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal failure in the first three decades of life. Mutations in 13 genes ( NPHP1 - NPHP11 , AHI1 , and CC2D2A ) cause NPHP with ubiquitous expression of the corresponding proteins consistent with the multiorgan involvement of NPHP-related diseases. The genotype–phenotype correlation in these ciliopathies can be explained by gene locus heterogeneity, allelism, and the impact of modifier genes. In some NPHP-related ciliopathies, the nature of the recessive mutations determines disease severity. In order to define the genotype–phenotype correlation more clearly, we evaluated a worldwide cohort of 440 patients from 365 families with NPHP-related ciliopathies, in whom both disease-causing alleles were identified. The phenotypes were ranked in the order of severity from degenerative to degenerative/dysplastic to dysplastic. A genotype of two null alleles caused a range of phenotypes, with an increasing order of severity of NPHP1 , NPHP3 , NPHP4 , NPHP5 , NPHP2 , NPHP10 , NPHP6 , to AHI1 . Only NPHP6 showed allelic influences on the phenotypes; the presence of two null mutations caused dysplastic phenotypes, whereas at least one missense allele rescued it to a milder degenerative phenotype. We also found nine novel mutations in the NPHP genes. Thus, our studies have important implications for genetic counseling and planning of renal replacement therapy.
-
mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a dna pooling and next generation sequencing strategy
Journal of Medical Genetics, 2011Co-Authors: Edgar A Otto, Gokul Ramaswami, Moumita Chaki, Susan J. Allen, Sabine Janssen, Weibin Zhou, Rannar Airik, Toby W Hurd, Amiya K Ghosh, Matthias T F WolfAbstract:Background Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised. Methods In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing. Results For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found. Conclusions The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC.
Friedhelm Hildebrandt - One of the best experts on this subject based on the ideXlab platform.
-
Gene mutation analysis in Iranian children with nephronophthisis: a two-center study.
Iranian journal of kidney diseases, 2015Co-Authors: Alaleh Gheissari, Maryam Harandavar, Friedhelm Hildebrandt, Daniela A. Braun, Maryam Sedghi, Nastaran Parsi, Alireza Merrikhi, Yahya Madihi, Farzaneh AghamohammadiAbstract:Introduction. Nephronophthisis is of the most commonly inherited ciliopathies that leads to end-stage renal disease in children. The NPHP1 gene is the first identified gene responsible for nephronophthisis and related diseases. This study assessed mutations of the NPHP1 gene in 16 Iranian families with at least one member presenting features of nephronophthisis. Materials and Methods. Fifty-seven patients diagnosed with chronic kidney disease or end-stage renal disease were referred to Imam Hossein Children Hospital, in Isfahan, Iran. The gene analysis study was carried on 16 patients and their first-degree relatives (40 DNA samples) suspicious of having nephronophthisis. The NPHP1 deletion analysis was performed for exons 5, 7, and 20 of the NPHP1 gene. Results. The patients' median age was 15 years. The mean and median age of the first presentation was 10.06 ± 2.59 years and 10.5 years, respectively. A homozygous deletion was identified in the NPHP1 gene spanning at least from exon 5 to exon 20 in two families. High-throughput mutation analysis identified a homozygous truncating mutation (c.1504C>T, p.R502*) in the NPHP5 in 5 families. Conclusions. By combining NPHP1 deletion analysis with multiplex-polymerase-chain-reaction-based high-throughput mutation analysis we could identify the molecular disease-cause in 7 of 15 families from Iran. In 8 families, the molecular disease cause remained unknown.
-
Identification of 99 novel mutations in a worldwide cohort of 1,056 patients with a nephronophthisis-related ciliopathy
Human Genetics, 2013Co-Authors: Jan Halbritter, Friedhelm Hildebrandt, Daniela A. Braun, Moumita Chaki, Susan J. Allen, Jonathan D. Porath, Katrina A. Diaz, Stefan Kohl, Neveen A. Soliman, Edgar A OttoAbstract:Nephronophthisis-related ciliopathies (NPHP-RC) are autosomal-recessive cystic kidney diseases. More than 13 genes are implicated in its pathogenesis to date, accounting for only 40 % of all cases. High-throughput mutation screenings of large patient cohorts represent a powerful tool for diagnostics and identification of novel NPHP genes. We here performed a new high-throughput mutation analysis method to study 13 established NPHP genes ( NPHP1 – NPHP13 ) in a worldwide cohort of 1,056 patients diagnosed with NPHP-RC. We first applied multiplexed PCR-based amplification using Fluidigm Access-Array™ technology followed by barcoding and next-generation resequencing on an Illumina platform. As a result, we established the molecular diagnosis in 127/1,056 independent individuals (12.0 %) and identified a single heterozygous truncating mutation in an additional 31 individuals (2.9 %). Altogether, we detected 159 different mutations in 11 out of 13 different NPHP genes, 99 of which were novel. Phenotypically most remarkable were two patients with truncating mutations in INVS/NPHP2 who did not present as infants and did not exhibit extrarenal manifestations. In addition, we present the first case of Caroli disease due to mutations in WDR19/NPHP13 and the second case ever with a recessive mutation in GLIS2/NPHP7 . This study represents the most comprehensive mutation analysis in NPHP-RC patients, identifying the largest number of novel mutations in a single study worldwide.
-
clinical characterization and nphp1 mutations in nephronophthisis and associated ciliopathies a single center experience
Saudi Journal of Kidney Diseases and Transplantation, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan ElkikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P <0.01). Homozygous NPHP1 deletions were detected in six patients from five of 17 (29.4%) studied families. Our study demonstrates the clinical phenotype of NPHP and related disorders in Egyptian children. Also, we report that homozygous NPHP1 deletions account for 29.4% of NPHP in the studied families in this cohort, thereby confirming the diagnosis of type-1 NPHP. Moreover, our findings confirm that NPHP1 deletions can indeed be responsible for JSRD.
-
Clinical characterization and NPHP1 mutations in nephronophthisis and associated ciliopathies: a single center experience.
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation Saudi Arabia, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan El-kikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P
-
Genotype–phenotype correlation in 440 patients with NPHP-related ciliopathies
Kidney international, 2011Co-Authors: Moumita Chaki, Julia Hoefele, Edgar A Otto, Gokul Ramaswami, Susan J. Allen, Sabine Janssen, Carsten Bergmann, John R. Heckenlively, Friedhelm HildebrandtAbstract:Nephronophthisis (NPHP), an autosomal recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal failure in the first three decades of life. Mutations in 13 genes ( NPHP1 - NPHP11 , AHI1 , and CC2D2A ) cause NPHP with ubiquitous expression of the corresponding proteins consistent with the multiorgan involvement of NPHP-related diseases. The genotype–phenotype correlation in these ciliopathies can be explained by gene locus heterogeneity, allelism, and the impact of modifier genes. In some NPHP-related ciliopathies, the nature of the recessive mutations determines disease severity. In order to define the genotype–phenotype correlation more clearly, we evaluated a worldwide cohort of 440 patients from 365 families with NPHP-related ciliopathies, in whom both disease-causing alleles were identified. The phenotypes were ranked in the order of severity from degenerative to degenerative/dysplastic to dysplastic. A genotype of two null alleles caused a range of phenotypes, with an increasing order of severity of NPHP1 , NPHP3 , NPHP4 , NPHP5 , NPHP2 , NPHP10 , NPHP6 , to AHI1 . Only NPHP6 showed allelic influences on the phenotypes; the presence of two null mutations caused dysplastic phenotypes, whereas at least one missense allele rescued it to a milder degenerative phenotype. We also found nine novel mutations in the NPHP genes. Thus, our studies have important implications for genetic counseling and planning of renal replacement therapy.
Matthias T F Wolf - One of the best experts on this subject based on the ideXlab platform.
-
mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a dna pooling and next generation sequencing strategy
Journal of Medical Genetics, 2011Co-Authors: Edgar A Otto, Gokul Ramaswami, Moumita Chaki, Susan J. Allen, Sabine Janssen, Weibin Zhou, Rannar Airik, Toby W Hurd, Amiya K Ghosh, Matthias T F WolfAbstract:Background Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised. Methods In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing. Results For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found. Conclusions The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC.
-
Nephronophthisis
Pediatric Nephrology, 2011Co-Authors: Matthias T F Wolf, Friedhelm HildebrandtAbstract:Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease and the most frequent genetic cause of end-stage renal disease up to the third decade of life. It is caused by mutations in 11 different genes, denoted nephrocystins ( NPHP1–11 , NPHP1L ). As an increasing number of these genes are identified, our knowledge of nephronophthisis is changing, thereby improving our understanding of the pathomechanisms in NPHP. Recent publications have described ciliary expression of nephrocystins together with other cystoproteins, such as polycystins 1 and 2 and fibrocystin. These findings have shifted our focus to a pathomechanism involving defects in ciliary function (ciliopathy) and planar cell polarity (PCP). In addition, discoveries of new nephrocystin genes have shown that the disease spectrum of NPHP is much broader than previously anticipated. Different forms of mutations within the same NPHP gene can cause different disease severity. In this review, we highlight the different hypotheses on the pathomechanisms for NPHP and underline the clinical variability of this disease. The clinical spectrum has become even more complex with the possibility of oligogenicity in NPHP.
-
Mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a DNA pooling and next generation sequencing strategy
Journal of medical genetics, 2010Co-Authors: Edgar A Otto, Gokul Ramaswami, Moumita Chaki, Susan J. Allen, Sabine Janssen, Weibin Zhou, Rannar Airik, Toby W Hurd, Amiya K Ghosh, Matthias T F WolfAbstract:Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised. In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing. For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found. The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC.
-
Mutation analysis in nephronophthisis using a combined approach of homozygosity mapping, CEL I endonuclease cleavage, and direct sequencing
Human mutation, 2008Co-Authors: Edgar A Otto, John F. O'toole, Massimo Attanasio, Susan J. Allen, Weibin Zhou, Matthias T F Wolf, Juliana Helou, Eric Wise, Shazia Ashraf, Friedhelm HildebrandtAbstract:Nephronophthisis (NPHP), an autosomal recessive kidney disease, is the most frequent genetic cause of chronic renal failure in the first three decades of life. Mutations in eight genes (NPHP1-8) have been identified. We here describe a combined approach for mutation screening of NPHP1, NPHP2, NPHP3, NPHP4, and NPHP5 in a worldwide cohort of 470 unrelated patients with NPHP. First, homozygous NPHP1 deletions were detected in 97 patients (21%) by multiplex PCR. Second, 25 patients with infantile NPHP were screened for mutations in inversin (NPHP2/INVS). We detected a novel compound heterozygous frameshift mutation (p.[Q485fs]+[R687fs]), and a homozygous nonsense mutation (p.R899X). Third, 37 patients presenting with NPHP and retinitis pigmentosa (Senior-Loken syndrome [SLS]) were screened for NPHP5/IQCB1 mutations by direct sequencing. We discovered five different (three novel) homozygous premature termination codon (PTC) mutations (p.F142fsX; p.R461X; p.R489X; p.W444X; and c.488-1G>A). The remaining 366 patients were further investigated for mutations in NPHP1, NPHP3, and NPHP4. We applied a "homozygosity only" strategy and typed three highly polymorphic microsatellite markers at the respective loci. A total of 32, eight, and 14 patients showed homozygosity, and were screened by heteroduplex crude celery extract (CEL I) endonuclease digests. The sensitivity of CEL I was established as 92%, as it detected 73 out of 79 different known mutations simply on agarose gels. A total of 10 novel PTC mutations were found in NPHP1 (p.P186fs, p.R347X, p.V492fs, p.Y509X, and c.1884+1G>A), in NPHP3 (c.3812+2T>C and p.R1259X), and in NPHP4 (p.R59X, p.T1004fs, and p.V1091fs). The combined homozygosity mapping and CEL I endonuclease mutation analysis approach allowed us to identify rare mutations in a large cohort of patients at low cost.
-
Mutational analysis of the RPGRIP1L gene in patients with Joubert syndrome and nephronophthisis
Kidney international, 2007Co-Authors: Matthias T F Wolf, John F. O'toole, Massimo Attanasio, Sophie Saunier, Rémi Salomon, N. Wanner, Ted Groshong, T. Stallmach, John A. Sayer, Rüdiger WaldherrAbstract:Joubert syndrome (JS) is an autosomal recessive disorder, consisting of mental retardation, cerebellar vermis aplasia, an irregular breathing pattern, and retinal degeneration. Nephronophthisis (NPHP) is found in 17-27% of these patients, which was designated JS type B. Mutations in four separate genes (AHI1, NPHP1, CEP290/NPHP6, and MKS3) are linked to JS. However, missense mutations in a new ciliary gene (RPGRIP1L) were found in type B patients. We analyzed a cohort of 56 patients with JS type B who were negative for mutations in three (AHI1, NPHP1, and CEP290/NPHP6) of the four genes previously linked to the syndrome. The 26 exons encoding RPGRIP1L were analyzed by means of PCR amplification, CEL I endonuclease digestion, and subsequent sequencing. Using this approach, four different mutations in the RPGRIP1L gene in five different families were identified and three were found to be novel mutations. Additionally, we verified that missense mutations are responsible for JS type B and cluster in exon 15 of the RPGRIP1L gene. Our studies confirm that a T615P mutation represents the most common mutation in the RPGRIP1L gene causing disease in about 8-10% of JS type B patients negative for NPHP1, NPHP6, or AHI1 mutations.
Heike Olbrich - One of the best experts on this subject based on the ideXlab platform.
-
Loss of Nephrocystin-3 Function Can Cause Embryonic Lethality, Meckel-Gruber-like Syndrome, Situs Inversus, and Renal-Hepatic-Pancreatic Dysplasia
American journal of human genetics, 2008Co-Authors: Carsten Bergmann, Bernhard Schermer, Ingolf Schmedding, Manfred Fliegauf, Heike Olbrich, Andreas Kispert, Valeska Frank, Nadina Ortiz Brüchle, Jan Kirschner, Bettina KränzlinAbstract:Many genetic diseases have been linked to the dysfunction of primary cilia, which occur nearly ubiquitously in the body and act as solitary cellular mechanosensory organelles. The list of clinical manifestations and affected tissues in cilia-related disorders (ciliopathies) such as nephronophthisis is broad and has been attributed to the wide expression pattern of ciliary proteins. However, little is known about the molecular mechanisms leading to this dramatic diversity of phenotypes. We recently reported hypomorphic NPHP3 mutations in children and young adults with isolated nephronophthisis and associated hepatic fibrosis or tapetoretinal degeneration. Here, we chose a combinatorial approach in mice and humans to define the phenotypic spectrum of NPHP3/NPHP3 mutations and the role of the nephrocystin-3 protein. We demonstrate that the pcy mutation generates a hypomorphic NPHP3 allele that is responsible for the cystic kidney disease phenotype, whereas complete loss of NPHP3 function results in situs inversus, congenital heart defects, and embryonic lethality in mice. In humans, we show that NPHP3 mutations can cause a broad clinical spectrum of early embryonic patterning defects comprising situs inversus, polydactyly, central nervous system malformations, structural heart defects, preauricular fistulas, and a wide range of congenital anomalies of the kidney and urinary tract (CAKUT). On the functional level, we show that nephrocystin-3 directly interacts with inversin and can inhibit like inversin canonical Wnt signaling, whereas nephrocystin-3 deficiency leads in Xenopus laevis to typical planar cell polarity defects, suggesting a role in the control of canonical and noncanonical (planar cell polarity) Wnt signaling.
-
Nephrocystin Specifically Localizes to the Transition Zone of Renal and Respiratory Cilia and Photoreceptor Connecting Cilia
Journal of the American Society of Nephrology : JASN, 2006Co-Authors: Manfred Fliegauf, Bernhard Schermer, Hartmut P. H. Neumann, Judit Horvath, Christian Von Schnakenburg, Heike Olbrich, Dominik N. Müller, Julia Thumfart, Gregory J. Pazour, Hanswalter ZentgrafAbstract:Nephronophthisis (NPHP) is a hereditary cystic kidney disorder that causes renal failure in children and young adults and can be associated with various extrarenal disorders, including retinitis pigmentosa. Six NPHP genes, whose functions are disrupted by autosomal recessive mutations in patients with NPHP, have been identified. The majority of patients with NPHP carry homozygous deletions of NPHP1 encoding nephrocystin. Previous data indicate that nephrocystin forms a complex at cell junctions and focal adhesions. Here, it is shown that nephrocystin specifically localizes at the ciliary base to the transition zone of renal and respiratory cilia and to photoreceptor connecting cilia. During in vitro ciliogenesis of primary human respiratory epithelial cells, nephrocystin can be detected first with a diffuse cytoplasmic localization as soon as cell polarization starts, and translocates to the transition zone when cilia are formed. In columnar respiratory cells, nephrocystin is attached tightly to the axonemal structure of the transition zone at a region that contains the calcium-sensitive cilia autotomy site. In patients with homozygous NPHP1 deletions, nephrocystin is absent from the entire respiratory cell, including the transition zone, which might be of interest for future diagnostic approaches. Cilia formation is not altered in primary nephrocystin-deficient respiratory cells, which is consistent with previous findings obtained for the Caenorhabditis elegans ortholog. In addition, it is shown that the localization pattern of intraflagellar transport proteins and nephrocystin differs, suggesting distinct functional roles. In conclusion, nephrocystin deficiency or dysfunction at the transition zone of renal monocilia and the photoreceptor connecting cilium might explain renal failure and retinal degeneration that are observed in patients with NPHP1.
-
mutations in a novel gene NPHP3 cause adolescent nephronophthisis tapeto retinal degeneration and hepatic fibrosis
Nature Genetics, 2003Co-Authors: Heike Olbrich, Julia Hoefele, Edgar A Otto, Matthias T F Wolf, Manfred Fliegauf, Andreas Kispert, Andreas Volz, Gursel Sasmaz, Ute Trauer, Richard ReinhardtAbstract:Nephronophthisis (NPHP), a group of autosomal recessive cystic kidney disorders, is the most common genetic cause of progressive renal failure in children and young adults1. NPHP may be associated with Leber congenital amaurosis, tapeto-retinal degeneration, cerebellar ataxia, cone-shaped epiphyses, congenital oculomotor apraxia and hepatic fibrosis2,3,4,5,6. Loci associated with an infantile type of NPHP on 9q22–q31 (NPHP2), juvenile types of NPHP on chromosomes 2q12–q13 (NPHP1) and 1p36 (NPHP4) and an adolescent type of NPHP on 3q21–q22 (NPHP3) have been mapped7,8,9,10. NPHP1 and NPHP4 have been identified11,12,13, and interaction of the respective encoded proteins nephrocystin and nephrocystin-4 has been shown13. Here we report the identification of NPHP3, encoding a novel 1,330-amino acid protein that interacts with nephrocystin. We describe mutations in NPHP3 in families with isolated NPHP and in families with NPHP with associated hepatic fibrosis or tapeto-retinal degeneration. We show that the mouse ortholog NPHP3 is expressed in the node, kidney tubules, retina, respiratory epithelium, liver, biliary tract and neural tissues. In addition, we show that a homozygous missense mutation in NPHP3 is probably responsible for the polycystic kidney disease (pcy) mouse phenotype14. Interventional studies in the pcy mouse have shown beneficial effects by modification of protein intake and administration of methylprednisolone15,16,17, suggesting therapeutic strategies for treating individuals with NPHP3.
-
Identification of a Gene Locus for Senior-Løken Syndrome in the Region of the Nephronophthisis Type 3 Gene
Journal of the American Society of Nephrology : JASN, 2002Co-Authors: Heymut Omran, Edgar A Otto, Karsten Häffner, Heike Olbrich, Andreas Volz, Gursel Sasmaz, Rachid Melkaoui, Thomas F. Wienker, Rudolf Korinthenberg, Matthias BrandisAbstract:ABSTRACT. Senior-Loken syndrome is an autosomal recessive disease with the main features of nephronophthisis (NPH) and Leber congenital amaurosis. The gene for adolescent nephronophthisis ( NPHP3 ) was recently localized to chromosome 3q21-q22. The hypothesis was tested that Senior-Loken syndrome (SLS) might localize to the same region by studying a kindred of German ancestry with extended consanguinity and typical findings of SLS. Twenty highly polymorphic markers located in the vicinity of the NPHP3 genetic region were tested. Haplotype analysis revealed homozygosity by descent in affected individuals, and linkage analysis yielded a parametric maximum multipoint logarithm of likelihood of odds (LOD) score of 3.14, thus identifying the first locus for SLS. The SLS1 locus is flanked by D3S1587 and D3S621 and contains a 14-cM interval that contains the whole critical NPHP3 region. Three additional families with SLS were studied, and evidence for genetic heterogeneity in one of them was found. Localization of a SLS locus to the region of NPHP3 opens the possibilities of both diseases arising by mutations within the same pleiotropic gene or two adjacent genes.
Susan J. Allen - One of the best experts on this subject based on the ideXlab platform.
-
Identification of 99 novel mutations in a worldwide cohort of 1,056 patients with a nephronophthisis-related ciliopathy
Human Genetics, 2013Co-Authors: Jan Halbritter, Friedhelm Hildebrandt, Daniela A. Braun, Moumita Chaki, Susan J. Allen, Jonathan D. Porath, Katrina A. Diaz, Stefan Kohl, Neveen A. Soliman, Edgar A OttoAbstract:Nephronophthisis-related ciliopathies (NPHP-RC) are autosomal-recessive cystic kidney diseases. More than 13 genes are implicated in its pathogenesis to date, accounting for only 40 % of all cases. High-throughput mutation screenings of large patient cohorts represent a powerful tool for diagnostics and identification of novel NPHP genes. We here performed a new high-throughput mutation analysis method to study 13 established NPHP genes ( NPHP1 – NPHP13 ) in a worldwide cohort of 1,056 patients diagnosed with NPHP-RC. We first applied multiplexed PCR-based amplification using Fluidigm Access-Array™ technology followed by barcoding and next-generation resequencing on an Illumina platform. As a result, we established the molecular diagnosis in 127/1,056 independent individuals (12.0 %) and identified a single heterozygous truncating mutation in an additional 31 individuals (2.9 %). Altogether, we detected 159 different mutations in 11 out of 13 different NPHP genes, 99 of which were novel. Phenotypically most remarkable were two patients with truncating mutations in INVS/NPHP2 who did not present as infants and did not exhibit extrarenal manifestations. In addition, we present the first case of Caroli disease due to mutations in WDR19/NPHP13 and the second case ever with a recessive mutation in GLIS2/NPHP7 . This study represents the most comprehensive mutation analysis in NPHP-RC patients, identifying the largest number of novel mutations in a single study worldwide.
-
High-throughput mutation analysis in patients with a nephronophthisis-associated ciliopathy applying multiplexed barcoded array-based PCR amplification and next-generation sequencing
Journal of medical genetics, 2012Co-Authors: Jan Halbritter, Moumita Chaki, Susan J. Allen, Jonathan D. Porath, Katrina A. Diaz, Brendan Tarrier, Jamie L. Innis, Robert H. Lyons, Constantinos J. StefanidisAbstract:Objective To identify disease-causing mutations within coding regions of 11 known NPHP genes ( NPHP1-NPHP11 ) in a cohort of 192 patients diagnosed with a nephronophthisis-associated ciliopathy, at low cost. Methods Mutation analysis was carried out using PCR-based 48.48 Access Array microfluidic technology (Fluidigm) with consecutive next-generation sequencing. We applied a 10-fold primer multiplexing approach allowing PCR-based amplification of 475 amplicons (251 exons) for 48 DNA samples simultaneously. After four rounds of amplification followed by indexing all of 192 patient-derived products with different barcodes in a subsequent PCR, 2×100 paired-end sequencing was performed on one lane of a HiSeq2000 instrument (Illumina). Bioinformatics analysis was performed using ‘CLC Genomics Workbench’ software. Potential mutations were confirmed by Sanger sequencing and shown to segregate. Results Bioinformatics analysis revealed sufficient coverage of 30×for 168/192 (87.5%) DNA samples (median 449×) and of 234 out of 251 targeted coding exons (sensitivity: 93.2%). For proof-of-principle, we analysed 20 known mutations and identified 18 of them in the correct zygosity state (90%). Likewise, we identified pathogenic mutations in 34/192 patients (18%) and discovered 23 novel mutations in the genes NPHP3 (7), NPHP4 (3), IQCB1 (4), CEP290 (7), RPGRIP1L (1), and TMEM67 (1). Additionally, we found 40 different single heterozygous missense variants of unknown significance. Conclusions We conclude that the combined approach of array-based multiplexed PCR-amplification on a Fluidigm Access Array platform followed by next-generation sequencing is highly cost-efficient and strongly facilitates diagnostic mutation analysis in broadly heterogeneous Mendelian disorders.
-
clinical characterization and nphp1 mutations in nephronophthisis and associated ciliopathies a single center experience
Saudi Journal of Kidney Diseases and Transplantation, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan ElkikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P <0.01). Homozygous NPHP1 deletions were detected in six patients from five of 17 (29.4%) studied families. Our study demonstrates the clinical phenotype of NPHP and related disorders in Egyptian children. Also, we report that homozygous NPHP1 deletions account for 29.4% of NPHP in the studied families in this cohort, thereby confirming the diagnosis of type-1 NPHP. Moreover, our findings confirm that NPHP1 deletions can indeed be responsible for JSRD.
-
Clinical characterization and NPHP1 mutations in nephronophthisis and associated ciliopathies: a single center experience.
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation Saudi Arabia, 2012Co-Authors: Neveen A. Soliman, Edgar A Otto, Friedhelm Hildebrandt, Susan J. Allen, Marwa M Nabhan, Ahmed M Badr, Maha Sheba, Sawsan Fadda, Ghada Gawdat, Hassan El-kikyAbstract:Nephronophthisis (NPHP) is a recessive disorder of the kidney that is the leading genetic cause of end-stage renal failure in children. Egypt is a country with a high rate of consanguineous marriages; yet, only a few studies have investigated the clinical and molecular characteristics of NPHP and related ciliopathies in the Egyptian population. We studied 20 children, from 17 independent families, fulfilling the clinical and the ultrasonographic criteria of NPHP. Analysis for a homozygous deletion of the NPHP1 gene was performed by polymerase chain reaction on the genomic DNA of all patients. Patients were best categorized as 75% juvenile NPHP, 5% infantile NPHP, and 20% Joubert syndrome-related disorders (JSRD). The mean age at diagnosis was 87.5 + 45.4 months, which was significantly late as compared with the age at onset of symptoms, 43.8 ± 29.7 months (P
-
Genotype–phenotype correlation in 440 patients with NPHP-related ciliopathies
Kidney international, 2011Co-Authors: Moumita Chaki, Julia Hoefele, Edgar A Otto, Gokul Ramaswami, Susan J. Allen, Sabine Janssen, Carsten Bergmann, John R. Heckenlively, Friedhelm HildebrandtAbstract:Nephronophthisis (NPHP), an autosomal recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal failure in the first three decades of life. Mutations in 13 genes ( NPHP1 - NPHP11 , AHI1 , and CC2D2A ) cause NPHP with ubiquitous expression of the corresponding proteins consistent with the multiorgan involvement of NPHP-related diseases. The genotype–phenotype correlation in these ciliopathies can be explained by gene locus heterogeneity, allelism, and the impact of modifier genes. In some NPHP-related ciliopathies, the nature of the recessive mutations determines disease severity. In order to define the genotype–phenotype correlation more clearly, we evaluated a worldwide cohort of 440 patients from 365 families with NPHP-related ciliopathies, in whom both disease-causing alleles were identified. The phenotypes were ranked in the order of severity from degenerative to degenerative/dysplastic to dysplastic. A genotype of two null alleles caused a range of phenotypes, with an increasing order of severity of NPHP1 , NPHP3 , NPHP4 , NPHP5 , NPHP2 , NPHP10 , NPHP6 , to AHI1 . Only NPHP6 showed allelic influences on the phenotypes; the presence of two null mutations caused dysplastic phenotypes, whereas at least one missense allele rescued it to a milder degenerative phenotype. We also found nine novel mutations in the NPHP genes. Thus, our studies have important implications for genetic counseling and planning of renal replacement therapy.
