Publications by authors named "Nina Mann"

27 Publications

  • Page 1 of 1

Recessive Mutations in as a Candidate of Monogenic Nephrotic Syndrome.

Kidney Int Rep 2021 Feb 10;6(2):472-483. Epub 2020 Nov 10.

Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Introduction: Most of the approximately 60 genes that if mutated cause steroid-resistant nephrotic syndrome (SRNS) are highly expressed in the glomerular podocyte, rendering SRNS a "podocytopathy."

Methods: We performed whole-exome sequencing (WES) in 1200 nephrotic syndrome (NS) patients.

Results: We discovered homozygous truncating and homozygous missense mutation in (synaptopodin-2) (p.Lys1124∗ and p.Ala1134Thr) in 2 patients with childhood-onset NS. We found SYNPO2 expression in both podocytes and mesangial cells; however, notably, immunofluorescence staining of adult human and rat kidney cryosections indicated that SYNPO2 is localized mainly in mesangial cells. Subcellular localization studies reveal that in these cells SYNPO2 partially co-localizes with α-actinin and filamin A-containing F-actin filaments. Upon transfection in mesangial cells or podocytes, EGFP-SYNPO2 co-localized with α-actinin-4, which gene is mutated in autosomal dominant SRNS in humans. SYNPO2 overexpression increases mesangial cell migration rate (MMR), whereas shRNA knockdown reduces MMR. Decreased MMR was rescued by transfection of wild-type mouse cDNA but only partially by cDNA representing mutations from the NS patients. The increased mesangial cell migration rate (MMR) by SYNPO2 overexpression was inhibited by ARP complex inhibitor CK666. shRNA knockdown in podocytes decreased active Rac1, which was rescued by transfection of wild-type cDNA but not by cDNA representing any of the 2 mutant variants.

Conclusion: We show that SYNPO2 variants may lead to Rac1-ARP3 dysregulation, and may play a role in the pathogenesis of nephrotic syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ekir.2020.10.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879128PMC
February 2021

Generation of Monogenic Candidate Genes for Human Nephrotic Syndrome Using 3 Independent Approaches.

Kidney Int Rep 2021 Feb 3;6(2):460-471. Epub 2020 Dec 3.

Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Introduction: Steroid-resistant nephrotic syndrome (SRNS) is the second most common cause of chronic kidney disease during childhood. Identification of 63 monogenic human genes has delineated 12 distinct pathogenic pathways.

Methods: Here, we generated 2 independent sets of nephrotic syndrome (NS) candidate genes to augment the discovery of additional monogenic causes based on whole-exome sequencing (WES) data from 1382 families with NS.

Results: We first identified 63 known monogenic causes of NS in mice from public databases and scientific publications, and 12 of these genes overlapped with the 63 known human monogenic SRNS genes. Second, we used a set of 64 genes that are regulated by the transcription factor Wilms tumor 1 (WT1), which causes SRNS if mutated. Thirteen of these WT1-regulated genes overlapped with human or murine NS genes. Finally, we overlapped these lists of murine and WT1 candidate genes with our list of 120 candidate genes generated from WES in 1382 NS families, to identify novel candidate genes for monogenic human SRNS. Using this approach, we identified 7 overlapping genes, of which 3 genes were shared by all datasets, including . We show that loss-of-function of leads to decreased CDC42 activity and reduced podocyte migration rate, both of which are rescued by overexpression of wild-type complementary DNA (cDNA), but not by cDNA representing the patient mutation.

Conclusion: Thus, we identified 3 novel candidate genes for human SRNS using 3 independent, nonoverlapping hypotheses, and generated functional evidence for as a novel potential monogenic cause of NS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ekir.2020.11.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879125PMC
February 2021

Mutations in Are a Novel Cause of Galloway-Mowat Syndrome.

J Am Soc Nephrol 2021 Mar 16;32(3):580-596. Epub 2021 Feb 16.

Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts

Background: Galloway-Mowat syndrome (GAMOS) is characterized by neurodevelopmental defects and a progressive nephropathy, which typically manifests as steroid-resistant nephrotic syndrome. The prognosis of GAMOS is poor, and the majority of children progress to renal failure. The discovery of monogenic causes of GAMOS has uncovered molecular pathways involved in the pathogenesis of disease.

Methods: Homozygosity mapping, whole-exome sequencing, and linkage analysis were used to identify mutations in four families with a GAMOS-like phenotype, and high-throughput PCR technology was applied to 91 individuals with GAMOS and 816 individuals with isolated nephrotic syndrome. and studies determined the functional significance of the mutations identified.

Results: Three biallelic variants of the transcriptional regulator were detected in six families with proteinuric kidney disease. Four families with a variant in the protein's zinc-finger (ZNF) domain have additional GAMOS-like features, including brain anomalies, cardiac defects, and skeletal defects. All variants destabilize the PRDM15 protein, and the ZNF variant additionally interferes with transcriptional activation. Morpholino oligonucleotide-mediated knockdown of Prdm15 in embryos disrupted pronephric development. Human wild-type RNA rescued the disruption, but the three variants did not. Finally, CRISPR-mediated knockout of in human podocytes led to dysregulation of several renal developmental genes.

Conclusions: Variants in can cause either isolated nephrotic syndrome or a GAMOS-type syndrome on an allelic basis. PRDM15 regulates multiple developmental kidney genes, and is likely to play an essential role in renal development in humans.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1681/ASN.2020040490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920168PMC
March 2021

Recessive variants impair actin remodeling and cause glomerulopathy in humans and mice.

Sci Adv 2021 Jan 1;7(1). Epub 2021 Jan 1.

Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.

Nephrotic syndrome (NS) is a leading cause of chronic kidney disease. We found recessive variants in two families with early-onset NS by exome sequencing. Overexpression of wild-type (WT) , but not cDNA constructs bearing patient variants, increased active CDC42 and promoted filopodia and podosome formation. Pharmacologic inhibition of CDC42 or its effectors, formin proteins, reduced NOS1AP-induced filopodia formation. knockdown reduced podocyte migration rate (PMR), which was rescued by overexpression of WT but not by constructs bearing patient variants. PMR in knockdown podocytes was also rescued by constitutively active or the formin Modeling a patient variant in knock-in human kidney organoids revealed malformed glomeruli with increased apoptosis. mice recapitulated the human phenotype, exhibiting proteinuria, foot process effacement, and glomerulosclerosis. These findings demonstrate that recessive variants impair CDC42/DIAPH-dependent actin remodeling, cause aberrant organoid glomerulogenesis, and lead to a glomerulopathy in humans and mice.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/sciadv.abe1386DOI Listing
January 2021

De novo TRIM8 variants impair its protein localization to nuclear bodies and cause developmental delay, epilepsy, and focal segmental glomerulosclerosis.

Am J Hum Genet 2021 02 27;108(2):357-367. Epub 2021 Jan 27.

Division of Nephrology, Columbia University, New York, NY 10032, USA. Electronic address:

Focal segmental glomerulosclerosis (FSGS) is the main pathology underlying steroid-resistant nephrotic syndrome (SRNS) and a leading cause of chronic kidney disease. Monogenic forms of pediatric SRNS are predominantly caused by recessive mutations, while the contribution of de novo variants (DNVs) to this trait is poorly understood. Using exome sequencing (ES) in a proband with FSGS/SRNS, developmental delay, and epilepsy, we discovered a nonsense DNV in TRIM8, which encodes the E3 ubiquitin ligase tripartite motif containing 8. To establish whether TRIM8 variants represent a cause of FSGS, we aggregated exome/genome-sequencing data for 2,501 pediatric FSGS/SRNS-affected individuals and 48,556 control subjects, detecting eight heterozygous TRIM8 truncating variants in affected subjects but none in control subjects (p = 3.28 × 10). In all six cases with available parental DNA, we demonstrated de novo inheritance (p = 2.21 × 10). Reverse phenotyping revealed neurodevelopmental disease in all eight families. We next analyzed ES from 9,067 individuals with epilepsy, yielding three additional families with truncating TRIM8 variants. Clinical review revealed FSGS in all. All TRIM8 variants cause protein truncation clustering within the last exon between residues 390 and 487 of the 551 amino acid protein, indicating a correlation between this syndrome and loss of the TRIM8 C-terminal region. Wild-type TRIM8 overexpressed in immortalized human podocytes and neuronal cells localized to nuclear bodies, while constructs harboring patient-specific variants mislocalized diffusely to the nucleoplasm. Co-localization studies demonstrated that Gemini and Cajal bodies frequently abut a TRIM8 nuclear body. Truncating TRIM8 DNVs cause a neuro-renal syndrome via aberrant TRIM8 localization, implicating nuclear bodies in FSGS and developmental brain disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2021.01.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7895901PMC
February 2021

A hemodialysis patient with difficulty ambulating: Answers.

Pediatr Nephrol 2021 Jan 20. Epub 2021 Jan 20.

Division of Nephrology, Boston Children's Hospital, 300 Longwood Ave, HU-319, Boston, MA, 02115, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00467-021-04931-1DOI Listing
January 2021

A hemodialysis patient with difficulty ambulating: Questions.

Pediatr Nephrol 2021 Jan 20. Epub 2021 Jan 20.

Division of Nephrology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, HU-319, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00467-020-04916-6DOI Listing
January 2021

DAAM2 Variants Cause Nephrotic Syndrome via Actin Dysregulation.

Am J Hum Genet 2020 12 23;107(6):1113-1128. Epub 2020 Nov 23.

Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA. Electronic address:

The discovery of >60 monogenic causes of nephrotic syndrome (NS) has revealed a central role for the actin regulators RhoA/Rac1/Cdc42 and their effectors, including the formin INF2. By whole-exome sequencing (WES), we here discovered bi-allelic variants in the formin DAAM2 in four unrelated families with steroid-resistant NS. We show that DAAM2 localizes to the cytoplasm in podocytes and in kidney sections. Further, the variants impair DAAM2-dependent actin remodeling processes: wild-type DAAM2 cDNA, but not cDNA representing missense variants found in individuals with NS, rescued reduced podocyte migration rate (PMR) and restored reduced filopodia formation in shRNA-induced DAAM2-knockdown podocytes. Filopodia restoration was also induced by the formin-activating molecule IMM-01. DAAM2 also co-localizes and co-immunoprecipitates with INF2, which is intriguing since variants in both formins cause NS. Using in vitro bulk and TIRF microscopy assays, we find that DAAM2 variants alter actin assembly activities of the formin. In a Xenopus daam2-CRISPR knockout model, we demonstrate actin dysregulation in vivo and glomerular maldevelopment that is rescued by WT-DAAM2 mRNA. We conclude that DAAM2 variants are a likely cause of monogenic human SRNS due to actin dysregulation in podocytes. Further, we provide evidence that DAAM2-associated SRNS may be amenable to treatment using actin regulating compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2020.11.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820625PMC
December 2020

Mutations in transcription factor CP2-like 1 may cause a novel syndrome with distal renal tubulopathy in humans.

Nephrol Dial Transplant 2021 01;36(2):237-246

Division of Nephrology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.

Background: An underlying monogenic cause of early-onset chronic kidney disease (CKD) can be detected in ∼20% of individuals. For many etiologies of CKD manifesting before 25 years of age, >200 monogenic causative genes have been identified to date, leading to the elucidation of mechanisms of renal pathogenesis.

Methods: In 51 families with echogenic kidneys and CKD, we performed whole-exome sequencing to identify novel monogenic causes of CKD.

Results: We discovered a homozygous truncating mutation in the transcription factor gene transcription factor CP2-like 1 (TFCP2L1) in an Arabic patient of consanguineous descent. The patient developed CKD by the age of 2 months and had episodes of severe hypochloremic, hyponatremic and hypokalemic alkalosis, seizures, developmental delay and hypotonia together with cataracts. We found that TFCP2L1 was localized throughout kidney development particularly in the distal nephron. Interestingly, TFCP2L1 induced the growth and development of renal tubules from rat mesenchymal cells. Conversely, the deletion of TFCP2L1 in mice was previously shown to lead to reduced expression of renal cell markers including ion transporters and cell identity proteins expressed in different segments of the distal nephron. TFCP2L1 localized to the nucleus in HEK293T cells only upon coexpression with its paralog upstream-binding protein 1 (UBP1). A TFCP2L1 mutant complementary DNA (cDNA) clone that represented the patient's mutation failed to form homo- and heterodimers with UBP1, an essential step for its transcriptional activity.

Conclusion: Here, we identified a loss-of-function TFCP2L1 mutation as a potential novel cause of CKD in childhood accompanied by a salt-losing tubulopathy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/ndt/gfaa215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7834595PMC
January 2021

Mutations of the Transcriptional Corepressor ZMYM2 Cause Syndromic Urinary Tract Malformations.

Authors:
Dervla M Connaughton Rufeng Dai Danielle J Owen Jonathan Marquez Nina Mann Adda L Graham-Paquin Makiko Nakayama Etienne Coyaud Estelle M N Laurent Jonathan R St-Germain Lot Snijders Blok Arianna Vino Verena Klämbt Konstantin Deutsch Chen-Han Wilfred Wu Caroline M Kolvenbach Franziska Kause Isabel Ottlewski Ronen Schneider Thomas M Kitzler Amar J Majmundar Florian Buerger Ana C Onuchic-Whitford Mao Youying Amy Kolb Daanya Salmanullah Evan Chen Amelie T van der Ven Jia Rao Hadas Ityel Steve Seltzsam Johanna M Rieke Jing Chen Asaf Vivante Daw-Yang Hwang Stefan Kohl Gabriel C Dworschak Tobias Hermle Mariëlle Alders Tobias Bartolomaeus Stuart B Bauer Michelle A Baum Eva H Brilstra Thomas D Challman Jacob Zyskind Carrie E Costin Katrina M Dipple Floor A Duijkers Marcia Ferguson David R Fitzpatrick Roger Fick Ian A Glass Peter J Hulick Antonie D Kline Ilona Krey Selvin Kumar Weining Lu Elysa J Marco Ingrid M Wentzensen Heather C Mefford Konrad Platzer Inna S Povolotskaya Juliann M Savatt Natalia V Shcherbakova Prabha Senguttuvan Audrey E Squire Deborah R Stein Isabelle Thiffault Victoria Y Voinova Michael J G Somers Michael A Ferguson Avram Z Traum Ghaleb H Daouk Ankana Daga Nancy M Rodig Paulien A Terhal Ellen van Binsbergen Loai A Eid Velibor Tasic Hila Milo Rasouly Tze Y Lim Dina F Ahram Ali G Gharavi Heiko M Reutter Heidi L Rehm Daniel G MacArthur Monkol Lek Kristen M Laricchia Richard P Lifton Hong Xu Shrikant M Mane Simone Sanna-Cherchi Andrew D Sharrocks Brian Raught Simon E Fisher Maxime Bouchard Mustafa K Khokha Shirlee Shril Friedhelm Hildebrandt

Am J Hum Genet 2020 10 4;107(4):727-742. Epub 2020 Sep 4.

Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA. Electronic address:

Congenital anomalies of the kidney and urinary tract (CAKUT) constitute one of the most frequent birth defects and represent the most common cause of chronic kidney disease in the first three decades of life. Despite the discovery of dozens of monogenic causes of CAKUT, most pathogenic pathways remain elusive. We performed whole-exome sequencing (WES) in 551 individuals with CAKUT and identified a heterozygous de novo stop-gain variant in ZMYM2 in two different families with CAKUT. Through collaboration, we identified in total 14 different heterozygous loss-of-function mutations in ZMYM2 in 15 unrelated families. Most mutations occurred de novo, indicating possible interference with reproductive function. Human disease features are replicated in X. tropicalis larvae with morpholino knockdowns, in which expression of truncated ZMYM2 proteins, based on individual mutations, failed to rescue renal and craniofacial defects. Moreover, heterozygous Zmym2-deficient mice recapitulated features of CAKUT with high penetrance. The ZMYM2 protein is a component of a transcriptional corepressor complex recently linked to the silencing of developmentally regulated endogenous retrovirus elements. Using protein-protein interaction assays, we show that ZMYM2 interacts with additional epigenetic silencing complexes, as well as confirming that it binds to FOXP1, a transcription factor that has also been linked to CAKUT. In summary, our findings establish that loss-of-function mutations of ZMYM2, and potentially that of other proteins in its interactome, as causes of human CAKUT, offering new routes for studying the pathogenesis of the disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2020.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536580PMC
October 2020

variants are associated with multiple congenital anomalies including ciliopathy phenotypes.

J Med Genet 2020 Jul 6. Epub 2020 Jul 6.

Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA

Background: Cilia are dynamic cellular extensions that generate and sense signals to orchestrate proper development and tissue homeostasis. They rely on the underlying polarisation of cells to participate in signalling. Cilia dysfunction is a well-known cause of several diseases that affect multiple organ systems including the kidneys, brain, heart, respiratory tract, skeleton and retina.

Methods: Among individuals from four unrelated families, we identified variants in ( that manifested in a variety of pathologies. In our proband, we also examined patient tissues. We depleted in frog embryos to generate a loss-of-function model. Finally, we tested the pathogenicity of patient variants through rescue experiments in the frog model.

Results: Patients with variants of were found to have a variety of phenotypes including cystic kidneys, nephrotic syndrome, hydrocephalus, limb abnormalities, congenital heart disease and craniofacial malformations. We also observed a loss of cilia in cystic kidney tissue of our proband. Knockdown of in embryos recapitulated many of these phenotypes and resulted in a loss of cilia in multiple tissues. Unlike introduction of wildtype in frog embryos depleted of introduction of patient variants was largely ineffective in restoring proper ciliation and tissue morphology in the kidney and brain suggesting that the variants were indeed detrimental to function.

Conclusion: These findings in both patient tissues and shed light on how mutations in may lead to tissue-specific manifestations of disease. DLG5 is essential for cilia and many of the patient phenotypes are in the ciliopathy spectrum.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/jmedgenet-2019-106805DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785698PMC
July 2020

Phenotype expansion of heterozygous FOXC1 pathogenic variants toward involvement of congenital anomalies of the kidneys and urinary tract (CAKUT).

Genet Med 2020 10 1;22(10):1673-1681. Epub 2020 Jun 1.

Department of Pediatrics, Boston Children's Hospital/Harvard Medical School, Boston, MA, USA.

Purpose: Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in childhood and adolescence. We aim to identify novel monogenic causes of CAKUT.

Methods: Exome sequencing was performed in 550 CAKUT-affected families.

Results: We discovered seven FOXC1 heterozygous likely pathogenic variants within eight CAKUT families. These variants are either never reported, or present in <5 alleles in the gnomAD database with ~141,456 controls. FOXC1 is a causal gene for Axenfeld-Rieger syndrome type 3 and anterior segment dysgenesis 3. Pathogenic variants in FOXC1 have not been detected in patients with CAKUT yet. Interestingly, mouse models for Foxc1 show severe CAKUT phenotypes with incomplete penetrance and variable expressivity. The FOXC1 variants are enriched in the CAKUT cohort compared with the control. Genotype-phenotype correlations showed that Axenfeld-Rieger syndrome or anterior segment dysgenesis can be caused by both truncating and missense pathogenic variants, and the missense variants are located at the forkhead domain. In contrast, for CAKUT, there is no truncating pathogenic variant, and all variants except one are located outside the forkhead domain.

Conclusion: We thereby expanded the phenotype of FOXC1 pathogenic variants toward involvement of CAKUT, which can potentially be explained by allelism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41436-020-0844-zDOI Listing
October 2020

CAKUT and Autonomic Dysfunction Caused by Acetylcholine Receptor Mutations.

Am J Hum Genet 2019 12 7;105(6):1286-1293. Epub 2019 Nov 7.

Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA. Electronic address:

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in the first three decades of life, and in utero obstruction to urine flow is a frequent cause of secondary upper urinary tract malformations. Here, using whole-exome sequencing, we identified three different biallelic mutations in CHRNA3, which encodes the α3 subunit of the nicotinic acetylcholine receptor, in five affected individuals from three unrelated families with functional lower urinary tract obstruction and secondary CAKUT. Four individuals from two families have additional dysautonomic features, including impaired pupillary light reflexes. Functional studies in vitro demonstrated that the mutant nicotinic acetylcholine receptors were unable to generate current following stimulation with acetylcholine. Moreover, the truncating mutations p.Thr337Asnfs81 and p.Ser340 led to impaired plasma membrane localization of CHRNA3. Although the importance of acetylcholine signaling in normal bladder function has been recognized, we demonstrate for the first time that mutations in CHRNA3 can cause bladder dysfunction, urinary tract malformations, and dysautonomia. These data point to a pathophysiologic sequence by which monogenic mutations in genes that regulate bladder innervation may secondarily cause CAKUT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2019.10.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904809PMC
December 2019

Mutations in KIRREL1, a slit diaphragm component, cause steroid-resistant nephrotic syndrome.

Kidney Int 2019 10 10;96(4):883-889. Epub 2019 Jul 10.

Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA. Electronic address:

Steroid-resistant nephrotic syndrome is a frequent cause of chronic kidney disease almost inevitably progressing to end-stage renal disease. More than 58 monogenic causes of SRNS have been discovered and majority of known steroid-resistant nephrotic syndrome causing genes are predominantly expressed in glomerular podocytes, placing them at the center of disease pathogenesis. Herein, we describe two unrelated families with steroid-resistant nephrotic syndrome with homozygous mutations in the KIRREL1 gene. One mutation showed high frequency in the European population (minor allele frequency 0.0011) and this patient achieved complete remission following treatment, but later progressed to chronic kidney disease. We found that mutant KIRREL1 proteins failed to localize to the podocyte cell membrane, indicating defective trafficking and impaired podocytes function. Thus, the KIRREL1 gene product has an important role in modulating the integrity of the slit diaphragm and maintaining glomerular filtration function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.kint.2019.06.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6756928PMC
October 2019

COL4A1 mutations as a potential novel cause of autosomal dominant CAKUT in humans.

Hum Genet 2019 Oct 22;138(10):1105-1115. Epub 2019 Jun 22.

Department of Medicine, Boston Children's Hospital, Enders 561, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA.

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease (~ 45%) that manifests before 30 years of age. The genetic locus containing COL4A1 (13q33-34) has been implicated in vesicoureteral reflux (VUR), but mutations in COL4A1 have not been reported in CAKUT. We hypothesized that COL4A1 mutations cause CAKUT in humans. We performed whole exome sequencing (WES) in 550 families with CAKUT. As negative control cohorts we used WES sequencing data from patients with nephronophthisis (NPHP) with no genetic cause identified (n = 257) and with nephrotic syndrome (NS) due to monogenic causes (n = 100). We identified a not previously reported heterozygous missense variant in COL4A1 in three siblings with isolated VUR. When examining 549 families with CAKUT, we identified nine additional different heterozygous missense mutations in COL4A1 in 11 individuals from 11 unrelated families with CAKUT, while no COL4A1 mutations were identified in a control cohort with NPHP and only one in the cohort with NS. Most individuals (12/14) had isolated CAKUT with no extrarenal features. The predominant phenotype was VUR (9/14). There were no clinical features of the COL4A1-related disorders (e.g., HANAC syndrome, porencephaly, tortuosity of retinal arteries). Whereas COL4A1-related disorders are typically caused by glycine substitutions in the collagenous domain (84.4% of variants), only one variant in our cohort is a glycine substitution within the collagenous domain (1/10). We identified heterozygous COL4A1 mutations as a potential novel autosomal dominant cause of CAKUT that is allelic to the established COL4A1-related disorders and predominantly caused by non-glycine substitutions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00439-019-02042-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6745245PMC
October 2019

Monogenic causes of chronic kidney disease in adults.

Kidney Int 2019 04 14;95(4):914-928. Epub 2019 Feb 14.

Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA. Electronic address:

Approximately 500 monogenic causes of chronic kidney disease (CKD) have been identified, mainly in pediatric populations. The frequency of monogenic causes among adults with CKD has been less extensively studied. To determine the likelihood of detecting monogenic causes of CKD in adults presenting to nephrology services in Ireland, we conducted whole exome sequencing (WES) in a multi-centre cohort of 114 families including 138 affected individuals with CKD. Affected adults were recruited from 78 families with a positive family history, 16 families with extra-renal features, and 20 families with neither a family history nor extra-renal features. We detected a pathogenic mutation in a known CKD gene in 42 of 114 families (37%). A monogenic cause was identified in 36% of affected families with a positive family history of CKD, 69% of those with extra-renal features, and only 15% of those without a family history or extra-renal features. There was no difference in the rate of genetic diagnosis in individuals with childhood versus adult onset CKD. Among the 42 families in whom a monogenic cause was identified, WES confirmed the clinical diagnosis in 17 (40%), corrected the clinical diagnosis in 9 (22%), and established a diagnosis for the first time in 16 families referred with CKD of unknown etiology (38%). In this multi-centre study of adults with CKD, a molecular genetic diagnosis was established in over one-third of families. In the evolving era of precision medicine, WES may be an important tool to identify the cause of CKD in adults.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.kint.2018.10.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6431580PMC
April 2019

Whole-Exome Sequencing Enables a Precision Medicine Approach for Kidney Transplant Recipients.

J Am Soc Nephrol 2019 02 17;30(2):201-215. Epub 2019 Jan 17.

Division of Nephrology,

Background: Whole-exome sequencing (WES) finds a CKD-related mutation in approximately 20% of patients presenting with CKD before 25 years of age. Although provision of a molecular diagnosis could have important implications for clinical management, evidence is lacking on the diagnostic yield and clinical utility of WES for pediatric renal transplant recipients.

Methods: To determine the diagnostic yield of WES in pediatric kidney transplant recipients, we recruited 104 patients who had received a transplant at Boston Children's Hospital from 2007 through 2017, performed WES, and analyzed results for likely deleterious variants in approximately 400 genes known to cause CKD.

Results: By WES, we identified a genetic cause of CKD in 34 out of 104 (32.7%) transplant recipients. The likelihood of detecting a molecular genetic diagnosis was highest for patients with urinary stone disease (three out of three individuals), followed by renal cystic ciliopathies (seven out of nine individuals), steroid-resistant nephrotic syndrome (nine out of 21 individuals), congenital anomalies of the kidney and urinary tract (ten out of 55 individuals), and chronic glomerulonephritis (one out of seven individuals). WES also yielded a molecular diagnosis for four out of nine individuals with ESRD of unknown etiology. The WES-related molecular genetic diagnosis had implications for clinical care for five patients.

Conclusions: Nearly one third of pediatric renal transplant recipients had a genetic cause of their kidney disease identified by WES. Knowledge of this genetic information can help guide management of both transplant patients and potential living related donors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1681/ASN.2018060575DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362619PMC
February 2019

Whole-Exome Sequencing Identifies Causative Mutations in Families with Congenital Anomalies of the Kidney and Urinary Tract.

J Am Soc Nephrol 2018 09 24;29(9):2348-2361. Epub 2018 Aug 24.

Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;

Background: Congenital anomalies of the kidney and urinary tract (CAKUT) are the most prevalent cause of kidney disease in the first three decades of life. Previous gene panel studies showed monogenic causation in up to 12% of patients with CAKUT.

Methods: We applied whole-exome sequencing to analyze the genotypes of individuals from 232 families with CAKUT, evaluating for mutations in single genes known to cause human CAKUT and genes known to cause CAKUT in mice. In consanguineous or multiplex families, we additionally performed a search for novel monogenic causes of CAKUT.

Results: In 29 families (13%), we detected a causative mutation in a known gene for isolated or syndromic CAKUT that sufficiently explained the patient's CAKUT phenotype. In three families (1%), we detected a mutation in a gene reported to cause a phenocopy of CAKUT. In 15 of 155 families with isolated CAKUT, we detected deleterious mutations in syndromic CAKUT genes. Our additional search for novel monogenic causes of CAKUT in consanguineous and multiplex families revealed a potential single, novel monogenic CAKUT gene in 19 of 232 families (8%).

Conclusions: We identified monogenic mutations in a known human CAKUT gene or CAKUT phenocopy gene as the cause of disease in 14% of the CAKUT families in this study. Whole-exome sequencing provides an etiologic diagnosis in a high fraction of patients with CAKUT and will provide a new basis for the mechanistic understanding of CAKUT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1681/ASN.2017121265DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115658PMC
September 2018

Case Report: Dual nebulised antibiotics among adults with cystic fibrosis and chronic infection.

F1000Res 2017 1;6:2079. Epub 2017 Dec 1.

Sheffield Adult Cystic Fibrosis Centre, Northern General Hospital, Sheffield, S5 7AU, UK.

Pulmonary exacerbations in adults with cystic fibrosis (CF) and chronic (Psae) infection are usually treated with dual intravenous antibiotics for 14 days, despite the lack of evidence for best practice. Intravenous antibiotics are commonly associated with various systemic adverse effects, including renal failure and ototoxicity. Inhaled antibiotics are less likely to cause systematic adverse effects, yet can achieve airway concentrations well above conventional minimum inhibitory concentrations. Typically one inhaled antibiotic is used at a time, but dual inhaled antibiotics (i.e. concomitant use of two different inhaled antibiotics) may have synergistic effect and achieve better results in the treatment of exacerbations. We presented anecdotal evidence for the use of dual inhaled antibiotics as an acute treatment for exacerbations, in the form of a case report. A female in her early thirties with CF and chronic Psae infection improved her FEV by 5% and 2% with two courses of dual inhaled antibiotics to treat exacerbations in 2016. In contrast, her FEV changed by 2%, -2%, 0% and 2%, respectively, with four courses of dual intravenous antibiotics in 2016. Baseline FEV was similar prior to all six courses of treatments. The greater FEV improvements with dual inhaled antibiotics compared to dual intravenous antibiotics suggest the potential role of using dual inhaled antibiotics to treat exacerbations among adults with CF and chronic Psae infection, especially since a greater choice of inhaled anti-pseudomonal antibiotics is now available. A previous study in 1985 has looked at the concomitant administration of inhaled tobramycin and carbenicillin, by reconstituting antibiotics designed for parenteral administration. To our knowledge, this is the first literature to describe the concomitant use of two different antibiotics specifically developed for delivery via the inhaled route.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.12688/f1000research.13298.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832909PMC
December 2017

A homozygous missense variant in VWA2, encoding an interactor of the Fraser-complex, in a patient with vesicoureteral reflux.

PLoS One 2018 19;13(1):e0191224. Epub 2018 Jan 19.

Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause (40-50%) of chronic kidney disease (CKD) in children. About 40 monogenic causes of CAKUT have so far been discovered. To date less than 20% of CAKUT cases can be explained by mutations in these 40 genes. To identify additional monogenic causes of CAKUT, we performed whole exome sequencing (WES) and homozygosity mapping (HM) in a patient with CAKUT from Indian origin and consanguineous descent. We identified a homozygous missense mutation (c.1336C>T, p.Arg446Cys) in the gene Von Willebrand factor A domain containing 2 (VWA2). With immunohistochemistry studies on kidneys of newborn (P1) mice, we show that Vwa2 and Fraser extracellular matrix complex subunit 1 (Fras1) co-localize in the nephrogenic zone of the renal cortex. We identified a pronounced expression of Vwa2 in the basement membrane of the ureteric bud (UB) and derivatives of the metanephric mesenchyme (MM). By applying in vitro assays, we demonstrate that the Arg446Cys mutation decreases translocation of monomeric VWA2 protein and increases translocation of aggregated VWA2 protein into the extracellular space. This is potentially due to the additional, unpaired cysteine residue in the mutated protein that is used for intermolecular disulfide bond formation. VWA2 is a known, direct interactor of FRAS1 of the Fraser-Complex (FC). FC-encoding genes and interacting proteins have previously been implicated in the pathogenesis of syndromic and/or isolated CAKUT phenotypes in humans. VWA2 therefore constitutes a very strong candidate in the search for novel CAKUT-causing genes. Our results from in vitro experiments indicate a dose-dependent neomorphic effect of the Arg446Cys homozygous mutation in VWA2.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0191224PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5774751PMC
February 2018

Exome sequencing in Jewish and Arab patients with rhabdomyolysis reveals single-gene etiology in 43% of cases.

Pediatr Nephrol 2017 Dec 5;32(12):2273-2282. Epub 2017 Aug 5.

Division of Nephrology, Department of Medicine, Boston Children's Hospital-Harvard Medical School, 300 Longwood Avenue HU319, Boston, MA, 02115, USA.

Background: Rhabdomyolysis is a clinical emergency that may cause acute kidney injury (AKI). It can be acquired or due to monogenic mutations. Around 60 different rare monogenic forms of rhabdomyolysis have been reported to date. In the clinical setting, identifying the underlying molecular diagnosis is challenging due to nonspecific presentation, the high number of causative genes, and current lack of data on the prevalence of monogenic forms.

Methods: We employed whole exome sequencing (WES) to reveal the percentage of rhabdomyolysis cases explained by single-gene (monogenic) mutations in one of 58 candidate genes. We investigated a cohort of 21 unrelated families with rhabdomyolysis, in whom no underlying etiology had been previously established.

Results: Using WES, we identified causative mutations in candidate genes in nine of the 21 families (43%). We detected disease-causing mutations in eight of 58 candidate genes, grouped into the following categories: (1) disorders of fatty acid metabolism (CPT2), (2) disorders of glycogen metabolism (PFKM and PGAM2), (3) disorders of abnormal skeletal muscle relaxation and contraction (CACNA1S, MYH3, RYR1 and SCN4A), and (4) disorders of purine metabolism (AHCY).

Conclusions: Our findings demonstrate a very high detection rate for monogenic etiologies using WES and reveal broad genetic heterogeneity for rhabdomyolysis. These results highlight the importance of molecular genetic diagnostics for establishing an etiologic diagnosis. Because these patients are at risk for recurrent episodes of rhabdomyolysis and subsequent risk for AKI, WES allows adequate prophylaxis and treatment for these patients and their family members and enables a personalized medicine approach.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00467-017-3755-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903869PMC
December 2017

A Dominant Mutation in Nuclear Receptor Interacting Protein 1 Causes Urinary Tract Malformations Dysregulation of Retinoic Acid Signaling.

J Am Soc Nephrol 2017 Aug 5;28(8):2364-2376. Epub 2017 Apr 5.

Departments of Medicine and

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of CKD in the first three decades of life. However, for most patients with CAKUT, the causative mutation remains unknown. We identified a kindred with an autosomal dominant form of CAKUT. By whole-exome sequencing, we identified a heterozygous truncating mutation (c.279delG, p.Trp93fs*) of the nuclear receptor interacting protein 1 gene () in all seven affected members. encodes a nuclear receptor transcriptional cofactor that directly interacts with the retinoic acid receptors (RARs) to modulate retinoic acid transcriptional activity. Unlike wild-type NRIP1, the altered NRIP1 protein did not translocate to the nucleus, did not interact with RAR, and failed to inhibit retinoic acid-dependent transcriptional activity upon expression in HEK293 cells. Notably, we also showed that treatment with retinoic acid enhanced NRIP1 binding to RAR RNA hybridization confirmed expression in the developing urogenital system of the mouse. In explant cultures of embryonic kidney rudiments, retinoic acid stimulated expression, whereas a pan-RAR antagonist strongly reduced it. Furthermore, mice heterozygous for a null allele of showed a CAKUT-spectrum phenotype. Finally, expression and knockdown experiments in confirmed an evolutionarily conserved role for in renal development. These data indicate that dominant mutations can cause CAKUT by interference with retinoic acid transcriptional signaling, shedding light on the well documented association between abnormal vitamin A levels and renal malformations in humans, and suggest a possible gene-environment pathomechanism in this disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1681/ASN.2016060694DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5533226PMC
August 2017

CITED4 induces physiologic hypertrophy and promotes functional recovery after ischemic injury.

JCI Insight 2016 Jun;1(9)

Cardiovascular Division of the Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.

The mechanisms by which exercise mediates its multiple cardiac benefits are only partly understood. Prior comprehensive analyses of the cardiac transcriptional components and microRNAs dynamically regulated by exercise suggest that the CBP/p300-interacting protein CITED4 is a downstream effector in both networks. While CITED4 has documented functional consequences in neonatal cardiomyocytes in vitro, nothing is known about its effects in the adult heart. To investigate the impact of cardiac CITED4 expression in adult animals, we generated transgenic mice with regulated, cardiomyocyte-specific CITED4 expression. Cardiac CITED4 expression in adult mice was sufficient to induce an increase in heart weight and cardiomyocyte size with normal systolic function, similar to the effects of endurance exercise training. After ischemia-reperfusion, CITED4 expression did not change initial infarct size but mediated substantial functional recovery while reducing ventricular dilation and fibrosis. Forced cardiac expression of CITED4 also induced robust activation of the mTORC1 pathway after ischemic injury. Moreover, pharmacological inhibition of mTORC1 abrogated CITED4's effects in vitro and in vivo. Together, these data establish CITED4 as a regulator of mTOR signaling that is sufficient to induce physiologic hypertrophy at baseline and mitigate adverse ventricular remodeling after ischemic injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/jci.insight.85904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4945110PMC
June 2016

Relationship between Exercise Parameters and Noninvasive Indices of Right Ventricular Function in Patients with Biventricular Circulation and Systemic Right Ventricle.

Congenit Heart Dis 2015 Sep-Oct;10(5):457-65. Epub 2015 Jan 19.

Department of Cardiology, Boston Children's Hospital, Boston, Mass, USA.

Objectives: In patients with systemic right ventricles (RVs) in a biventricular circulation, exercise capacity and RV function often deteriorate over time and echocardiographic assessment of systemic RV function is difficult. The purpose of this study was to examine the relationship between exercise capacity and RV function and to determine which noninvasive imaging parameters correlate most closely with exercise capacity.

Design: Patients with a systemic RV (D-loop transposition of the great arteries [TGA] after atrial switch procedure or physiologically "corrected" TGA) who underwent cardiopulmonary exercise testing (CPX) and noninvasive imaging (cardiac magnetic resonance [CMR] and echocardiography [echo]) within 1 year of CPX were identified. Regression analysis was used to evaluate the relationship between exercise variables and noninvasive indices of ventricular function.

Results: We identified 92 patients with 149 encounters (mean age 31.0 years, 61% men, 70% D-loop TGA) meeting inclusion criteria. Statistically significant correlations between % predicted peak oxygen uptake (%pVO2 ) and RV ejection fraction (EF) (r = 0.29, P = .0007), indexed RV end-systolic volume (r = -0.25, P = .002), and Tei index (r = -0.22, P = .03) were found. In patients without additional hemodynamically significant lesions, the correlations between %pVO2 and RV EF (r = 0.37, P = .0007) and the Tei index (r = -0.28, P = .03) strengthened and a correlation emerged between %pVO2 and dP/dtic (r = 0.31, P = .007). On multivariable analysis, Tei index was the only statistically significant correlate of %pVO2 (P = .04).

Conclusions: In patients with systemic RVs in a biventricular circulation, CMR-derived RVEF and echo-derived Tei index correlate with %pVO2 . On multivariable analysis, the Tei index was the strongest predictor of peak %pVO2 response.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/chd.12248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4506894PMC
August 2016

Can exercise teach us how to treat heart disease?

Circulation 2012 Nov;126(22):2625-35

Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCULATIONAHA.111.060376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4000019PMC
November 2012

C/EBPβ controls exercise-induced cardiac growth and protects against pathological cardiac remodeling.

Cell 2010 Dec;143(7):1072-83

Dana-Farber Cancer Institute, Harvard Medical School, 3 Blackfan Circle, CLS Building, Floor 11, Boston, MA 02115, USA.

The heart has the ability to grow in size in response to exercise, but little is known about the transcriptional mechanisms underlying physiological hypertrophy. Adult cardiomyocytes have also recently been proven to hold the potential for proliferation, a process that could be of great importance for regenerative medicine. Using a unique RT-PCR-based screen against all transcriptional components, we showed that C/EBPβ was downregulated with exercise, whereas the expression of CITED4 was increased. Reduction of C/EBPβ in vitro and in vivo resulted in a phenocopy of endurance exercise with cardiomyocyte hypertrophy and proliferation. This proliferation was mediated, at least in part, by the increased CITED4. Importantly, mice with reduced cardiac C/EBPβ levels displayed substantial resistance to cardiac failure upon pressure overload. These data indicate that C/EBPβ represses cardiomyocyte growth and proliferation in the adult mammalian heart and that reduction in C/EBPβ is a central signal in physiologic hypertrophy and proliferation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cell.2010.11.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035164PMC
December 2010

Precise engineering of targeted nanoparticles by using self-assembled biointegrated block copolymers.

Proc Natl Acad Sci U S A 2008 Feb 13;105(7):2586-91. Epub 2008 Feb 13.

Department of Chemical Engineering, Harvard-MIT Center of Cancer Nanotechnology Excellence, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.

There has been progressively heightened interest in the development of targeted nanoparticles (NPs) for differential delivery and controlled release of drugs. Despite nearly three decades of research, approaches to reproducibly formulate targeted NPs with the optimal biophysicochemical properties have remained elusive. A central challenge has been defining the optimal interplay of parameters that confer molecular targeting, immune evasion, and drug release to overcome the physiological barriers in vivo. Here, we report a strategy for narrowly changing the biophysicochemical properties of NPs in a reproducible manner, thereby enabling systematic screening of optimally formulated drug-encapsulated targeted NPs. NPs were formulated by the self-assembly of an amphiphilic triblock copolymer composed of end-to-end linkage of poly(lactic-co-glycolic-acid) (PLGA), polyethyleneglycol (PEG), and the A10 aptamer (Apt), which binds to the prostate-specific membrane antigen (PSMA) on the surface of prostate cancer (PCa) cells, enabling, respectively, controlled drug release, "stealth" properties for immune evasion, and cell-specific targeting. Fine-tuning of NP size and drug release kinetics was further accomplished by controlling the copolymer composition. By using distinct ratios of PLGA-b-PEG-b-Apt triblock copolymer with PLGA-b-PEG diblock copolymer lacking the A10 Apt, we developed a series of targeted NPs with increasing Apt densities that inversely affected the amount of PEG exposure on NP surface and identified the narrow range of Apt density when the NPs were maximally targeted and maximally stealth, resulting in most efficient PCa cell uptake in vitro and in vivo. This approach may contribute to further development of targeted NPs as highly selective and effective therapeutic modalities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.0711714105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268180PMC
February 2008