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Biomedical subjects

Martin R Pollak

Publications and source records attributed to Martin R Pollak.

At least 19 recordsLinked to original sources
PubMed2026

Precision Diagnosis in APOL1 Kidney Disease With the p.N264K M1 Protective Variant.

IMPORTANCE: The APOL1 M1 (p.N264K) variant protects against G2-associated APOL1 focal segmental glomerulosclerosis (FSGS) and chronic kidney disease (CKD). However, the utility of knowing an individual's M1 status in guiding kidney disease diagnosis and other clinical scenarios remains underexplored. OBJECTIVE: To test 2 hypotheses: (1) in patients with APOL1 high-risk (HR) genotype kidney disease with at least 1 G2 allele, M1 can distinguish APOL1 CKD from non-APOL1 CKD; (2) in people with APOL1 low-risk (LR) genotypes, M1 is independently associated with protection against FSGS and CKD. DESIGN, SETTING, AND PARTICIPANTS: Retrospective case-control study using data from 2 tertiary care hospitals (Columbia University Irving Medical Center and Mass General Brigham Biobank) and population-based data (the UK Biobank [UKB], Electronic Medical Records and Genomics [eMERGE-III], and All of Us [AoU]). Participants were individuals with a diagnosis of FSGS or steroid-resistant nephrotic syndrome (SRNS), individuals with CKD, and controls. EXPOSURES: Exposures included the M1 variant (p.N264K) obtained from exome or genome sequencing data, sex, and genetic ancestry. MAIN OUTCOME AND MEASURE: The main outcome was the presence or absence of kidney disease, defined as FSGS or non-FSGS CKD, compared with non-kidney disease controls. Association between the M1 variant and disease status was assessed using odds ratios (ORs). RESULTS: A total of 107 696 individuals (54 994 [51.1%] female; 8779 [8.2%] with African ancestry, 78 475 [72.9%] with European ancestry, and 16 129 [15.0%] with multiethnic ancestry), including 3460 with FSGS or SRNS, 24 382 with non-FSGS CKD kidney disease, and 79 854 controls were enrolled in the discovery cohort. In the APOL1-HR group (1413 participants), M1 was significantly inversely associated with FSGS or SRNS cases compared with controls without kidney disease (OR, 0.20; 95% CI, 0.04-0.63; P = 3.69 × 10-3). Among individuals with CKD with APOL1-HR genotypes, M1 was 4 times more frequent in those whose CKD was not due to FSGS or SRNS. Importantly, electronic health record and biopsy review identified an alternative, non-APOL1 cause for CKD in nearly all APOL1-HR-M1 cases. There was no association between individuals with APOL1-LR genotypes with M1 and protection against CKD or FSGS. CONCLUSIONS AND RELEVANCE: In this case-control study of 107 696 individuals, presence of an APOL1-HR genotype M1 was significantly associated with protection against kidney disease, suggesting that it may have a role as a genetic modifier. Patients with CKD with an APOL1-HR genotype and M1 should be evaluated for an alternative and potentially treatable cause of their CKD.

Humans↗
PubMed2022

ADAR regulates APOL1 via A-to-I RNA editing by inhibition of MDA5 activation in a paradoxical biological circuit.

APOL1 risk variants are associated with increased risk of kidney disease in patients of African ancestry, but not all individuals with the APOL1 high-risk genotype develop kidney disease. As APOL1 gene expression correlates closely with the degree of kidney cell injury in both cell and animal models, the mechanisms regulating APOL1 expression may be critical determinants of risk allele penetrance. The APOL1 messenger RNA includes Alu elements at the 3' untranslated region that can form a double-stranded RNA structure (Alu-dsRNA) susceptible to posttranscriptional adenosine deaminase acting on RNA (ADAR)-mediated adenosine-to-inosine (A-to-I) editing, potentially impacting gene expression. We studied the effects of ADAR expression and A-to-I editing on APOL1 levels in podocytes, human kidney tissue, and a transgenic APOL1 mouse model. In interferon-γ (IFN-γ)-stimulated human podocytes, ADAR down-regulates APOL1 by preventing melanoma differentiation-associated protein 5 (MDA5) recognition of dsRNA and the subsequent type I interferon (IFN-I) response. Knockdown experiments showed that recognition of APOL1 messenger RNA itself is an important contributor to the MDA5-driven IFN-I response. Mathematical modeling suggests that the IFN-ADAR-APOL1 network functions as an incoherent feed-forward loop, a biological circuit capable of generating fast, transient responses to stimuli. Glomeruli from human kidney biopsies exhibited widespread editing of APOL1 Alu-dsRNA, while the transgenic mouse model closely replicated the edited sites in humans. APOL1 expression in mice was inversely correlated with Adar1 expression under IFN-γ stimuli, supporting the idea that ADAR regulates APOL1 levels in vivo. ADAR-mediated A-to-I editing is an important regulator of APOL1 expression that could impact both penetrance and severity of APOL1-associated kidney disease.

Humans↗
PubMed2006

TRPC6 in glomerular health and disease: what we know and what we believe.

Mutations in TRPC6, a member of the transient receptor potential (TRP) superfamily of non-selective cation channels, have been identified as causing a familial form of focal segmental glomerulosclerosis, a disease characterized by proteinuria and progressive renal failure. Here we review the effect of disease-associated mutations on TRPC6 function and place TRPC6 within the context of other proteins central to glomerular and podocyte function. Finally, the known roles of TRPC6 in the kidney and other organ systems are used as a framework to discuss possible signaling pathways that TRPC6 may modulate during normal glomerular function and in disease states.

Animals↗
PubMed2006

Alpha-actinin-4 is required for normal podocyte adhesion.

Mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant human kidney disease. Mice deficient in alpha-actinin-4 develop a recessive phenotype characterized by kidney failure, proteinuria, glomerulosclerosis, and retraction of glomerular podocyte foot processes. However, the mechanism by which alpha-actinin-4 deficiency leads to glomerular disease has not been defined. Here, we examined the effect of alpha-actinin-4 deficiency on the adhesive properties of podocytes in vivo and in a cell culture system. In alpha-actinin-4-deficient mice, we observed a decrease in the number of podocytes per glomerulus compared with wild-type mice as well as the presence of podocyte markers in the urine. Podocyte cell lines generated from alpha-actinin-4-deficient mice were less adherent than wild-type cells to glomerular basement membrane (GBM) components collagen IV and laminin 10 and 11. We also observed markedly reduced adhesion of alpha-actinin-4-deficient podocytes under increasing shear stresses. This adhesion deficit was restored by transfecting cells with alpha-actinin-4-GFP. We tested the strength of the integrin receptor-mediated linkages to the cytoskeleton by applying force to microbeads bound to integrin using magnetic pulling cytometry. Beads bound to alpha-actinin-4-deficient podocytes showed greater displacement in response to an applied force than those bound to wild-type cells. Consistent with integrin-dependent alpha-actinin-4-mediated adhesion, phosphorylation of beta1-integrins on alpha-actinin-4-deficient podocytes is reduced. We rescued the phosphorylation deficit by transfecting alpha-actinin-4 into alpha-actinin-4-deficient podocytes. These results suggest that alpha-actinin-4 interacts with integrins and strengthens the podocyte-GBM interaction thereby stabilizing glomerular architecture and preventing disease.

Actinin↗
PubMed2006

Calcium receptor stimulates chemotaxis and secretion of MCP-1 in GnRH neurons in vitro: potential impact on reduced GnRH neuron population in CaR-null mice.

The factors controlling the migration of mammalian gonadotropin-releasing hormone (GnRH) neurons from the nasal placode to the hypothalamus are not well understood. We studied whether the extracellular calcium-sensing receptor (CaR) promotes migration/chemotaxis of GnRH neurons. We demonstrated expression of CaR in GnRH neurons in the murine basal forebrain and in two GnRH neuronal cell lines: GT1-7 (hypothalamus derived) and GN11 (olfactory bulb derived). Elevated extracellular Ca(2+) concentrations promoted chemotaxis of both cell types, with a greater effect in GN11 cells. This effect was CaR mediated, as, in both cell types, overexpression of a dominant-negative CaR attenuated high Ca(2+)-stimulated chemotaxis. We also demonstrated expression of a beta-chemokine, monocyte chemoattractant protein-1 (MCP-1), and its receptor, CC motif receptor-2 (CCR2), in the hypothalamic GnRH neurons as well as in GT1-7 and GN11 cells. Exogenous MCP-1 stimulated chemotaxis of both cell lines in a dose-dependent fashion; the effect was greater in GN11 than in GT1-7 cells, consistent with the higher CCR2 mRNA levels in GN11 cells. Activating the CaR stimulated MCP-1 secretion in GT1-7 but not in GN11 cells. MCP-1 secreted in response to CaR stimulation is biologically active, as conditioned medium from GT1-7 cells treated with high Ca(2+) promoted chemotaxis of GN11 cells, and this effect was partially attenuated by a neutralizing antibody to MCP-1. Finally, in the preoptic area of anterior hypothalamus, the number of GnRH neurons was approximately 27% lower in CaR-null mice than in mice expressing the CaR gene. We conclude that the CaR may be a novel regulator of GnRH neuronal migration likely involving, in part, MCP-1.

Animals↗
PubMed2006

The genetic basis of human glomerular disease.

Clinical and molecular research aimed to understand glomerular disease has emerged to one of the most active areas in renal research at large. The unraveling of genetic causes resulting in proteinuria has helped to define roles for each component of the glomerular filtration barrier in the development of urinary protein loss. Although most of the inherited glomerular diseases have in common defects in the podocyte, the glomerular basement membrane is also of critical importance for normal kidney permselectivity. This review summarizes recent progress in the eludication of genetic causes of glomerular disease and discusses their implications for the understanding of the pathogenic mechanisms, which can lead to disruption of the glomerular filtration barrier.

Genetic Predisposition to Disease↗
PubMed2005

Stem cell engraftment at the endosteal niche is specified by the calcium-sensing receptor.

During mammalian ontogeny, haematopoietic stem cells (HSCs) translocate from the fetal liver to the bone marrow, where haematopoiesis occurs throughout adulthood. Unique features of bone that contribute to a microenvironmental niche for stem cells might include the known high concentration of calcium ions at the HSC-enriched endosteal surface. Cells respond to extracellular ionic calcium concentrations through the seven-transmembrane-spanning calcium-sensing receptor (CaR), which we identified as being expressed on HSCs. Here we show that, through the CaR, the simple ionic mineral content of the niche may dictate the preferential localization of adult mammalian haematopoiesis in bone. Antenatal mice deficient in CaR had primitive haematopoietic cells in the circulation and spleen, whereas few were found in bone marrow. CaR-/- HSCs from fetal liver were normal in number, in proliferative and differentiative function, and in migration and homing to the bone marrow. Yet they were highly defective in localizing anatomically to the endosteal niche, behaviour that correlated with defective adhesion to the extracellular matrix protein, collagen I. CaR has a function in retaining HSCs in close physical proximity to the endosteal surface and the regulatory niche components associated with it.

Animals↗
PubMed2005

Mutational and Biological Analysis of alpha-actinin-4 in focal segmental glomerulosclerosis.

Mutations in the alpha-actinin-4 gene (ACTN4) cause an autosomal dominant form of focal segmental glomerulosclerosis (FSGS). A mutational analysis was performed of ACTN4 in DNA from probands with a family history of FSGS as well as in individuals with nonfamilial FSGS. The possible contribution of noncoding variation in ACTN4 to the development of FSGS also was assessed. Multiple nucleotide variants were identified in coding and noncoding sequence. The segregation of nonsynonymous coding sequence variants was examined in the relevant families. Only a small number of nucleotide changes that seemed likely to be causing (or contributing to) disease were identified. Sequence changes that predicted I149del, W59R, V801M, R348Q, R837Q, and R310Q changes were identified. For studying their biologic relevance and their potential roles in the pathogenesis of FSGS, these variants were expressed as GFP-fusion proteins in cultured podocytes. F-actin binding assays also were performed. Three of these variants (W59R, I149del, and V801M) showed clear cellular mislocalization in the form of aggregates adjacent to the nucleus. Two of these mislocalized variants (W59R and I149del) also showed an increased actin-binding activity. The I149del mutation segregated with disease; W59R was found to be a de novo mutation in the proband. A total of five ACTN4 mutations that are believed to be disease causing (three reported previously and two novel) as well as a number of variants with unclear contribution to disease now have been identified. The possibility that some of these other variants increase the susceptibility to FSGS cannot be excluded. ACTN4 mutations seem to account for approximately 4% of familial FSGS.

Actinin↗
PubMed2005

TRPC6 is a glomerular slit diaphragm-associated channel required for normal renal function.

Progressive kidney failure is a genetically and clinically heterogeneous group of disorders. Podocyte foot processes and the interposed glomerular slit diaphragm are essential components of the permeability barrier in the kidney. Mutations in genes encoding structural proteins of the podocyte lead to the development of proteinuria, resulting in progressive kidney failure and focal segmental glomerulosclerosis. Here, we show that the canonical transient receptor potential 6 (TRPC6) ion channel is expressed in podocytes and is a component of the glomerular slit diaphragm. We identified five families with autosomal dominant focal segmental glomerulosclerosis in which disease segregated with mutations in the gene TRPC6 on chromosome 11q. Two of the TRPC6 mutants had increased current amplitudes. These data show that TRPC6 channel activity at the slit diaphragm is essential for proper regulation of podocyte structure and function.

Adolescent↗
PubMed2005

Cultured podocytes establish a size-selective barrier regulated by specific signaling pathways and demonstrate synchronized barrier assembly in a calcium switch model of junction formation.

Podocytes form unique cell-cell junctions (slit diaphragms) that are central to glomerular selectivity, although regulation and mechanisms of slit diaphragm assembly are poorly understood. With the use of cultured podocytes, a paracellular permeability flux assay was established to characterize properties of the size-selective barrier. Paracellular flux of differentiated podocytes was measured using anionic fluorescent dextrans of 3, 10, 40, and 70 kD. Podocytes form a highly selective barrier with a 160-fold difference in flux from the 3-kD dextran (11 pmol/min) to the 70-kD dextran (0.06 pmol/min). Barrier development was dependent on podocyte differentiation and not affected by dextran charge. Puromycin, a known podocyte toxin, increased flux 250% in a dose-dependent manner without affecting cell viability. Screening with modulators of specific signaling pathways identified reversible increases in flux with Src tyrosine and Rho kinase inhibition. The calcium switch model of epithelial junction assembly was modified to determine whether podocytes regulate barrier assembly. When cultured in low calcium for 90 min, flux increased by 300% and consistently returned to baseline 24 to 48 h after switching to normal calcium. Similar to classical epithelial junctions, barrier recovery occurred in the presence of cyclohexamide, an inhibitor of protein synthesis. During the calcium switch, there were reversible changes in localization and detergent solubility of the slit diaphragm protein ZO-1 and alpha-actinin-4, whereas nephrin and podocin solubility were unchanged. Taken together, these findings demonstrate that cultured podocytes develop a selective size barrier that is regulated by specific signaling pathways, and similar to classical epithelial junctions, podocytes demonstrate synchronized assembly of the barrier.

Animals↗
PubMed2005

Comparative linkage analysis and visualization of high-density oligonucleotide SNP array data.

BACKGROUND: The identification of disease-associated genes using single nucleotide polymorphisms (SNPs) has been increasingly reported. In particular, the Affymetrix Mapping 10 K SNP microarray platform uses one PCR primer to amplify the DNA samples and determine the genotype of more than 10,000 SNPs in the human genome. This provides the opportunity for large scale, rapid and cost-effective genotyping assays for linkage analysis. However, the analysis of such datasets is nontrivial because of the large number of markers, and visualizing the linkage scores in the context of genome maps remains less automated using the current linkage analysis software packages. For example, the haplotyping results are commonly represented in the text format. RESULTS: Here we report the development of a novel software tool called CompareLinkage for automated formatting of the Affymetrix Mapping 10 K genotype data into the "Linkage" format and the subsequent analysis with multi-point linkage software programs such as Merlin and Allegro. The new software has the ability to visualize the results for all these programs in dChip in the context of genome annotations and cytoband information. In addition we implemented a variant of the Lander-Green algorithm in the dChipLinkage module of dChip software (V1.3) to perform parametric linkage analysis and haplotyping of SNP array data. These functions are integrated with the existing modules of dChip to visualize SNP genotype data together with LOD score curves. We have analyzed three families with recessive and dominant diseases using the new software programs and the comparison results are presented and discussed. CONCLUSIONS: The CompareLinkage and dChipLinkage software packages are freely available. They provide the visualization tools for high-density oligonucleotide SNP array data, as well as the automated functions for formatting SNP array data for the linkage analysis programs Merlin and Allegro and calling these programs for linkage analysis. The results can be visualized in dChip in the context of genes and cytobands. In addition, a variant of the Lander-Green algorithm is provided that allows parametric linkage analysis and haplotyping.

Family Health↗
PubMed2004

Alpha-actinin-4-mediated FSGS: an inherited kidney disease caused by an aggregated and rapidly degraded cytoskeletal protein.

Focal segmental glomerulosclerosis (FSGS) is a common pattern of renal injury, seen as both a primary disorder and as a consequence of underlying insults such as diabetes, HIV infection, and hypertension. Point mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant form of human FSGS. We characterized the biological effect of these mutations by biochemical assays, cell-based studies, and the development of a new mouse model. We found that a fraction of the mutant protein forms large aggregates with a high sedimentation coefficient. Localization of mutant alpha-actinin-4 in transfected and injected cells, as well as in situ glomeruli, showed aggregates of the mutant protein. Video microscopy showed the mutant alpha-actinin-4 to be markedly less dynamic than the wild-type protein. We developed a "knockin" mouse model by replacing Actn4 with a copy of the gene bearing an FSGS-associated point mutation. We used cells from these mice to show increased degradation of mutant alpha-actinin-4, mediated, at least in part, by the ubiquitin-proteasome pathway. We correlate these findings with studies of alpha-actinin-4 expression in human samples. "Knockin" mice with a disease-associated Actn4 mutation develop a phenotype similar to that observed in humans. Comparison of the phenotype in wild-type, heterozygous, and homozygous Actn4 "knockin" and "knockout" mice, together with our in vitro data, suggests that the phenotypes in mice and humans involve both gain-of-function and loss-of-function mechanisms.

Actinin↗
PubMed2004

NPHS2 R229Q functional variant is associated with microalbuminuria in the general population.

BACKGROUND: Microalbuminuria is a risk factor for developing end-stage renal disease and cardiovascular events. Mutations in NPHS2 have been shown to cause autosomal-recessive nephrotic syndrome. Recently, a functional polymorphism of this gene (R229Q) was described and associated with a maturity-onset form of nephrotic syndrome. We have investigated whether the carrier status of this novel genetic variant is associated with microalbuminuria in individuals from the general population. METHODS: Demographic, cardiovascular risk factors, and renal phenotypes in 1577 individuals from a cross-sectional-based study were collected following the general guidelines of the WHO-MONICA project (monitoring trends and determinants in cardiovascular diseases). Blood and urine samples were obtained. Microalbuminuria was determined using a semiquantitative protocol, and DNA was extracted from peripheral lymphocytes. RESULTS: A strong association was found between the 229Q allele and microalbuminuria (P= 0.008). The presence of the 229Q allele was still associated with a 2.77-fold increased risk of presenting microalbuminuria even after adjustment for age, ethnicity, hypertension, obesity, and diabetes in a multiple logistic regression model. In addition, a statistically significant interaction was identified between the presence of the 229Q allele and body mass index (BMI) (P= 0.01), suggesting an additive effect between the 229Q allele and other risk factors for microalbuminuria. CONCLUSION: These data have important implications for the understanding of microalbuminuria in the general population and may contribute to better ways of disease prediction and prevention.

Adult↗
PubMed2003

The genetic basis of FSGS and steroid-resistant nephrosis.

Studies of Mendelian forms of focal segmental glomerulosclerosis (FSGS) and nephrotic syndrome have provided new insights into the mechanism of these diseases. Congenital nephrotic syndrome and familial forms of FSGS form a spectrum of podocyte diseases of varying severity and age of onset. Mutations in both nephrin gene (NPHS1) alleles lead to congenital nephrosis, podocyte foot process efacement, and loss of slit-diaphragm structure. Mutations in both podocin gene (NPHS2) alleles lead to a wide range of human disease, from childhood-onset steroid-resistant FSGS and minimal change disease to adult-onset FSGS. Dominantly inherited mutations in ACTN4, the alpha-actinin-4 gene, can lead to a slowly progressive adult-onset form of FSGS. In addition, FSGS is observed as part of several rare multisystem inherited syndromes. Here we review recent progress in understanding the genetic basis of FSGS in humans.

Animals↗
PubMed2003

The calcium-sensing receptor is required for normal calcium homeostasis independent of parathyroid hormone.

The extracellular calcium-sensing receptor (CaR; alternate gene names, CaR or Casr) is a membrane-spanning G protein-coupled receptor. CaR is highly expressed in the parathyroid gland, and is activated by extracellular calcium (Ca(2+)(o)). Mice homozygous for null mutations in the CaR gene (CaR(-/-)) die shortly after birth because of the effects of severe hyperparathyroidism and hypercalcemia. A wide variety of functions have been attributed to CaR. However, the lethal CaR-deficient phenotype has made it difficult to dissect the direct effect of CaR deficiency from the secondary effects of hyperparathyroidism and hypercalcemia. We therefore generated parathyroid hormone-deficient (PTH-deficient) CaR(-/-) mice (Pth(-/-)CaR(-/-)) by intercrossing mice heterozygous for the null CaR allele with mice heterozygous for a null Pth allele. We show that genetic ablation of PTH is sufficient to rescue the lethal CaR(-/-) phenotype. Pth(-/-)CaR(-/-) mice survive to adulthood with no obvious difference in size or appearance relative to control Pth(-/-) littermates. Histologic examination of most organs did not reveal abnormalities. These Pth(-/-)CaR(-/-) mice exhibit a much wider range of values for serum calcium and renal excretion of calcium than we observe in control littermates, despite the absence of any circulating PTH. Thus, CaR is necessary for the fine regulation of serum calcium levels and renal calcium excretion independent of its effect on PTH secretion.

Alleles↗
PubMed2003

Mice deficient in alpha-actinin-4 have severe glomerular disease.

Dominantly inherited mutations in ACTN4, which encodes alpha-actinin-4, cause a form of human focal and segmental glomerulosclerosis (FSGS). By homologous recombination in ES cells, we developed a mouse model deficient in Actn4. Mice homozygous for the targeted allele have no detectable alpha-actinin-4 protein expression. The number of homozygous mice observed was lower than expected under mendelian inheritance. Surviving mice homozygous for the targeted allele show progressive proteinuria, glomerular disease, and typically death by several months of age. Light microscopic analysis shows extensive glomerular disease and proteinaceous casts. Electron microscopic examination shows focal areas of podocyte foot-process effacement in young mice, and diffuse effacement and globally disrupted podocyte morphology in older mice. Despite the widespread distribution of alpha-actinin-4, histologic examination of mice showed abnormalities only in the kidneys. In contrast to the dominantly inherited human form of ACTN4-associated FSGS, here we show that the absence of alpha-actinin-4 causes a recessive form of disease in mice. Cell motility, as measured by lymphocyte chemotaxis assays, was increased in the absence of alpha-actinin-4. We conclude that alpha-actinin-4 is required for normal glomerular function. We further conclude that the nonsarcomeric forms of alpha-actinin (alpha-actinin-1 and alpha-actinin-4) are not functionally redundant. In addition, these genetic studies demonstrate that the nonsarcomeric alpha-actinin-4 is involved in the regulation of cell movement.

Actinin↗
PubMed2002

NPHS2 mutations in late-onset focal segmental glomerulosclerosis: R229Q is a common disease-associated allele.

Mutations in NPHS2, encoding podocin, have been identified in childhood onset focal and segmental glomerulosclerosis (FSGS). The role of NPHS2 in adult disease is less well defined. We studied 30 families with FSGS and apparent autosomal recessive inheritance and 91 individuals with primary FSGS. We screened family members for NPHS2 mutations. NPHS2 mutations appeared to be responsible for disease in nine of these families. In six families, the affected individuals were compound heterozygotes for a nonconservative R229Q amino acid substitution. This R229Q variant has an allele frequency of 3.6% in a control population. In these families, R229Q was the only mutation identified on one of the two disease-associated NPHS2 alleles. We used in vitro-translated podocin and purified nephrin to investigate the effect of R229Q on their interaction and found decreased nephrin binding to the R229Q podocin. These data suggest that this common polymorphism contributes to the development of FSGS. Chromosomes bearing the R229Q mutation share a common haplotype defining an approximately 0.2-Mb region. R229Q appears to enhance susceptibility to FSGS in association with a second mutant NPHS2 allele. Identification of R229Q mutations may be of clinical importance, as NPHS2-associated disease appears to define a subgroup of FSGS patients unresponsive to corticosteroids.

Adolescent↗