Assessment of combined α-GAL enzyme activity and lyso-GL3 for Fabry disease screening in women with chronic kidney disease.

INTRODUCTION: The spectrum of clinical presentation of Fabry disease (FD) in women is broad and challenging. The aim is to evaluate the effectiveness of an alternative screening method for FD in women. METHODS: A collaborative multicenter cross-sectional study to evaluate the sensitivity and specificity of the combination of two tests (α-GAL enzyme activity assay and lyso-GL3 assay) for the diagnosis of FD in women. We included women with chronic kidney disease (CKD) stages 3 to 5, receiving conservative treatment or on dialysis programs, from different nephrology services in Brazil. RESULTS: We evaluated 1874 patients that underwent blood collection for α-GAL and lyso-GL3 assays. Isolated decreased α-GAL enzyme activity was found in 64 patients (3.5%), while isolated increased lyso-GL3 levels were found in 67 patients (3.6%), with one patient presenting alterations in both tests. All cases with low α-GAL enzyme activity and/or increased lyso-GL3 levels underwent genetic analysis for FD variants (132 performed GLA genetic test). Low α-GAL enzyme activity had higher sensitivity and specificity to detect FD compared to the other measures (elevated lyso-GL3 alone or both altered). The negative predictive value (NPV) of α-GAL activity was 99%, and the positive predictive value (PPV) was 9.2%. For lyso-GL3 assay, the specificity was 99.7% and the PPV was 2.9%, therefore considered inferior to α-GAL assay. Both assays altered, had higher PPV (100%) and higher NPV (99.7%) considered the best method. We found 7 cases of GLA gene variants found, resulting in an initial prevalence of 0.37% for FD in this sample female population. CONCLUSION: This study contributes to the diagnostic value of the biomarkers α-GAL and lyso-GL3 in the context of FD in women with CKD. The combination of these biomarkers was an effective approach for the diagnosis of the disease, with high PPV and NPV.

Baseline Characteristics of Fabry Disease "Amenable" Migalastat Patients in Argentinian Cohort.

Fabry disease (FD) is a multisystem lysosomal storage disorder induced by genetic variants in the alpha-galactosidase A (αGalA) gene. Some FD patients have GLA variants with a reduction in overall αGalA enzymatic activity due to mutated proteins with reduced stability, caused by protein misfolding and premature degradation, but the αGalA catalytic activity remains conserved ("amenable" genetic variants). To correct this misfolding and to prevent premature degradation, migalastat, a small iminosugar molecule was developed. We report the clinical characteristics of FD "amenable" cohort patients from Argentina, prior to starting treatment with migalastat. Seventeen Fabry adult patients were recruited from 13 Argentinian Centers; 8 males (47.1%) and 9 females (52.9%) were included. All genotypes included were missense-type "amenables" mutations. Some classic FD typical early manifestations were more frequent in patients with "classic" versus "late-onset" FD phenotype (pain, p=0.002; cornea verticillata, p=0.019). There was a statistically significant difference in estimated glomerular filtration rate in the "classic" versus "late-onset" phenotype (p=0.026) but no difference between genders (p=0.695). Left ventricular mass was similar between genders (p=0.145) and phenotypes (p=0.303). Cardiovascular risk factors were present among "late-onset" females (obesity 50% and smoke 25%). In patients who started "de novo" migalastat, the main indications were (i) heart disease, (ii) kidney damage, and (iii) pain, while in "switched from prior enzyme replacement therapy" patients, the most frequent indication was "patient decision;" this coincides with publications by other authors.

Prevalence of Fabry disease in patients with chronic kidney disease: A systematic review and meta-analysis.

Fabry disease (FD) is an X-linked lysosomal storage disease caused by pathogenic variants in the GLA gene. It has a wide range of clinical manifestations, typically related to the specific underlying GLA variant. One of the main features of FD is kidney involvement; therefore, several studies have addressed the prevalence of FD in all types of patients with chronic kidney disease. We performed a systematic review and meta-analysis of screening studies in chronic kidney disease patients, including those on dialysis, had undergone a kidney transplantation, and those who did not receive kidney replacement therapy, and assessed the prevalence of pathogenic variants in these cohorts. Fifty-five studies were included, involving a total of 84,062 individuals. Of these, 251 cases were positive for FD; a third of the reported GLA variants were of a benign phenotype (37.8%), followed by classical phenotype (31.7%), late onset (15.5%), and of uncertain significance (14.7%). The overall prevalence among dialysis patients was 0.10% (CI95%, 0.06-0.15), 0.28% (CI95%, 0.06-0.15) among patients with kidney transplantation, and 0.17% (CI95%, 0.11-0.39) among those without kidney replacement therapy. Although the overall prevalence of FD is low in patients with kidney involvement, screening, especially in patients who have not yet undergone kidney replacement therapy, is important, in order to provide timely and effective treatment interventions, including disease modifying therapies. The prevalence of kidney involvement in females with Fabry Disease is lower but this should not lead to inadequate follow up. Further research is also needed on the impact of genetic variants of uncertain significance to elucidate their role in Fabry disease.

Prevalence of papillary muscle hypertrophy in fabry disease.

BACKGROUND AND AIMS: Fabry disease (FD) is an X-linked genetic lysosomal disease, in which a deficit in the alpha-galactosidase A enzyme results in lysosomal build-up of globotriaosylceramide in several organs, causing cardiac, renal and cerebrovascular complications. The aim of this study was to assess the prevalence of papillary muscle hypertrophy (PMH) in patients with FD. METHODS: A group of 63 patients with FD and a positive genetic diagnosis were studied and were divided into two groups: one included 24 patients with FD and LVH and another group included 39 patients with FD and without LVH. Papillary muscles were measured from the left parasternal short axis view, defining PMH as a diastolic thickness greater than 11 mm in any diameter. RESULTS: Patients with FD and LVH had a high prevalence of anterolateral PMH (66.6%), and such prevalence was lower for the posteromedial PMH (33.3%). However, patients who had not yet developed LVH had a high prevalence of anterolateral PMH (33.3%). CONCLUSIONS: Patients with FD in the pre-clinical stage (without LVH) have a high prevalence of PMH, especially involving the anterolateral papillary muscle. This finding could be an early marker for the development of LVH, allowing to suspect the disease during its early stages, and begin enzyme replacement therapy in the appropriate patients.

Genetic and phenotypic profile of Fabry disease in the population of Vale do Paraiba and Eastern São Paulo.

INTRODUCTION: Fabry disease (FD) is an inborn error of metabolism characterized by α-galactosidase A deficiency. The primary objective was to evaluate the genetic and phenotypic profile of Fabry disease in hemodialysis. METHODS: Observational cohort study to determine the incidence of genetic variations and phenotypic changes for FD in hemodialysis patients in the Paraiba Valley and Eastern São Paulo. Genetic testing for the GLA gene was performed for men and women over 12 years of age at the hemodialysis clinics between January 2016 and December 2019 as a screening protocol. RESULTS: The cases came from screening exams of the index case among patients with chronic kidney disease, resulting in 17 families and totaling 82 patients under study. The classification of the most prevalent variant was that of uncertain significance (54%), followed by the pathogenic variant (46%). Five patients in two families were described with two types of variants not previously described in the literature, with pathogenic behavior. Comparing the types of variants, the presence of a pathogenic variant was associated with higher levels of lysoGB3, lower values for alpha-GAL activity and higher frequency of symptoms related to FD. CONCLUSION: We characterized an extensive population of patients with FD variants with rich genetic, clinical and biomarker details. We believe that this study can help to better characterize the Brazilian population with FD and the most frequent types of variants.

Aseptic meningitis in Fabry disease due to a novel GLA variant: an expanded phenotype?

BACKGROUND: F abry disease (FD) is an X-linked lysosomal storage disorder with accumulation of globotriosylceramide, causing neurologic involvement mainly as acroparesthesias and cerebrovascular disease. Aseptic meningitis has been reported in 11 patients with FD, but no prior study has correlated alpha-galactosidase (GLA) specific variants with meningitis. We present in this manuscript a family in which a novel GLA pathogenic variant was associated with aseptic meningitis in 2 of 5 family members. METHODS: This study began with identifying the proband, then screening family members for FD symptoms and evaluating symptomatic individuals for genetic and biochemical status. All patients underwent magnetic resonance imaging, and those with headache underwent cerebrospinal fluid (CSF) analysis. RESULTS: Five patients (3 females) from a single family were included in this study. Mean age at diagnosis was 20.6 years. Two patients (40%) had aseptic meningitis; one of them also had cerebrovascular events. C-reactive protein and erythrocyte sedimentation rate were elevated during aseptic meningitis episodes. Both patients responded to intravenous methylprednisolone with resolution of fever, headache, and vomiting. One of them recurred and needed chronic immunosuppression with azathioprine. CONCLUSION: We described aseptic meningitis in a family with a novel GLA variant. Meningitis might be a common phenomenon in FD and not a particularity of this variant. Understanding the mechanisms underlying meningitis and its association with cerebrovascular events may lead to a new paradigm of treatment for stroke in these patients. Further prospective studies with CSF collection in patients with FD and recurrent headache could help to elucidate this question.

Biomarkers for Monitoring Renal Damage Due to Fabry Disease in Patients Treated with Migalastat: A Review for Nephrologists.

Nephropathy is a major Fabry disease complication. Kidney biopsies reveal glomerulosclerosis even in pediatric patients. The main manifestations of Fabry nephropathy include reduced glomerular filtration rate and proteinuria. In 2016, an oral pharmacological Chaperone was approved to treat Fabry patients with "amenable" mutations. Because (i) Fabry disease is a rare disorder that frequently causes kidney damage, and (ii) a new therapeutic is currently available, it is necessary to review wich biomarkers are useful for nephropathy follow-up among Fabry "amenable" patients receiving migalastat. The literature search was conducted in MEDLINE, EMBASE, SCOPUS, Cochrane, and Google academic. Prospective studies in which renal biomarkers were the dependent variable or criterion, with at least 6 months of follow-up, were included. Finally, we recorded relevant information in an ad hoc database and summarized the main results. To date, the main useful biomarker for nephropathy monitoring among Fabry "amenable" patients receiving migalastat is glomerular filtration rate estimated by equations that include serum creatinine.

Screening for Fabry disease in Argentina in male patients with chronic kidney disease at all stages.

We report three patients diagnosed with Fabry disease through a screening study which included individuals suffering from chronic kidney disease (CKD) at any stage. The study recruited 1740 male patients, and three Fabry patients were diagnosed, resulting in a frequency of 0.17%. The analysis by CKD stage group revealed frequencies of 3.03%, 0.77% and 0.17%, in CKD1, CKD3 and CKD5, respectively. Pedigree analysis was carried out for these families, with a high ratio index: pedigree (1:16). This study underlines the importance of considering Fabry disease in the differential diagnosis at every stage of CKD, including the early ones, and stresses the possibility of finding patients with late onset phenotypes.

Functional characterization of novel variants found in patients with suspected Fabry disease.

The deficiency or absence of the lysosomal hydrolase α-Galactosidase A results in Fabry disease (FD), a rare and underdiagnosed X-linked disorder. The symptoms caused by FD have a direct relation with the variant present in the gene coding α-Galactosidase A (GLA) and enzyme residual activity, and it can vary drastically between men and women of the same family. Here, we present four novel variants found in patients with suspicion of FD. The patients were screened for FD by enzymatic activity and/or DNA sequencing, which showed four novel GLA missense variants. To confirm the potential pathogenicity of these variants, we employed site-directed mutagenesis. GLA wild-type and mutant plasmids were transfected into mammalian cells; RNA and proteins were extracted for expression and enzymatic activity analysis. The patients presented the variants p.Ile133Asn, p.Lys140Thr, p.Lys168Gln and p.Pro323Thr in the GLA. In vitro analysis showed pathogenic potential of three variants and one tolerated variant. The variants p.Ile133Asn and p.Lys168Gln showed no residual activity and, therefore, leading to classical phenotype, and the variant p.Lys140Thr, which presented 22% of residual activity, was considered a mild variant leading to non-classical phenotype. The variant p.Pro323Thr presented 66.7% of residual activity and alone, it is not enough to cause FD.

Recommendations for the diagnosis and management of Fabry disease in pediatric patients: a document from the Rare Diseases Committee of the Brazilian Society of Nephrology (Comdora-SBN).

Fabry disease (FD) is a genetic disease, with X-chromosome linked inheritance, due to variants in the GLA gene that encodes the α-galactosidase A (α-GAL) enzyme. The purpose of the present study was to create a consensus aiming to standardize the recommendations regarding the renal involvement of FD with guidelines on the diagnosis, screening, and treatment of pediatric patients. This consensus is an initiative of the Rare Diseases Committee (Comdora) of the Brazilian Society of Nephrology (SBN). Randomized controlled clinical studies and studies with real-life data added to the authors' experience were considered for this review. The result of this consensus was to help manage patient and physician expectations regarding treatment outcomes. Thus, this consensus document recommends the investigation of the pediatric family members of an index case, as well as cases with suggestive clinical signs. From the diagnosis, assess all possible FD impairments and grade through scales. From an extensive review of the literature including pediatric protocols and particularly evaluating pediatric cases from general studies, it can be concluded that the benefits of early treatment are great, especially in terms of neuropathic pain and renal impairment parameters and outweigh the possible adverse effects that were mainly manifested by infusion reactions.

Brazilian consensus recommendations for the diagnosis, screening, and treatment of individuals with fabry disease: Committee for Rare Diseases - Brazilian Society of Nephrology/2021.

Fabry disease (FD) is an X-linked inherited disorder caused by mutations in the GLA gene encoding enzyme alpha-galactosidase A (α-Gal A). The purpose of this study was to produce a consensus statement to standardize the recommendations concerning kidney involvement in FD and provide advice on the diagnosis, screening, and treatment of adult and pediatric patients. This consensus document was organized from an initiative led by the Committee for Rare Diseases (Comdora) of the Brazilian Society of Nephrology (SBN). The review considered randomized clinical trials, real-world data studies, and the expertise of its authors. The purpose of this consensus statement is to help manage patient and physician expectations concerning the outcomes of treatment. Our recommendations must be interpreted within the context of available evidence. The decisions pertaining to each individual case must be made with the involvement of patients and their families and take into account not only the potential cost of treatment, but also concurrent conditions and personal preferences. The Comdora intends to update these recommendations regularly so as to reflect recent literature evidence, real-world data, and appreciate the professional experience of those involved. This consensus document establishes clear criteria for the diagnosis of FD and for when to start or stop specific therapies or adjuvant measures, to thus advise the medical community and standardize clinical practice.

Frequency of Fabry disease in a juvenile idiopathic arthritis cohort.

BACKGROUND: Fabry disease (FD) is a rare, X-linked, multisystemic lysosomal storage disorder (LSD) that results from a deficiency in the hydrolase alpha-galactosidase A (⍺-GalA). During childhood, classic FD symptomatology is rare. The majority of children may show non-specific symptoms, including in the musculoskeletal system. The prevalence of FD among juvenile idiopathic arthritis (JIA) patients is unknown. OBJECTIVE: This study aimed to identify the frequency of FD in a JIA cohort, characterizing early clinical symptoms, enzyme titers, and GLA genotyping. METHODS: Children with JIA followed in a tertiary Children Hospital cohort were selected. Clinical, laboratory and familiar information were recorded. Molecular genetic testing to detect GLA gene mutations was performed in girls and enzymatic analysis in boys. RESULTS: In 89 patients (56.2% female, age at disease onset: 8.93 ± 4.35 years), one male (1.12%) patient presented pathogenic mutation in GLA gene, c.1244 T > C p.L415P, one female patient had a variant of uncertain significance c.38C > T (p.Ala13Val). Three additional (3.4%) patients had the enzymatic activity of alpha-galactosidase slightly decreased. We observed the presence of intronic variants in 44.44% of patients in our cohort: c.1000-22C > T; c.370-81_-77del; c.640-16A > G; c.10C > T; c.548-125C > G and c.-12G > A. These variants and their combination were associated with clinical symptoms in our cohort. CONCLUSIONS: The incidence of FD in our cohort was 1.12%. Intronic variants were associated with symptoms previously described in the literature. Screening for FD in JIA may be a reasonable strategy for those with an atypical pattern of pain.

Screening of family members of chronic kidney disease patients with Fabry disease mutations: a very important and underrated task / Triagem de familiares de pacientes com doença renal crônica com mutação na doença de Fabry: uma tarefa muito importante e subestimada

ABSTRACT Introduction: Fabry disease is a chronic, progressive, and multi-system hereditary condition, related to an Xq22 mutation in X chromosome, which results in deficiency of alpha-galactosidase enzyme, hence reduced capacity of globotriaosylceramide degradation. Objectives: to evaluate the prevalence of Fabry disease (FD) mutations, as well as its signs and symptoms, among relatives of chronic kidney disease (CKD) patients diagnosed with FD during a previously conducted study, named "Clinical and epidemiological analysis of Fabry disease in dialysis centers in Brazil". Methods: a cross-sectional study was carried out, and data was collected by interviewing the relatives of patients enrolled in the Brazil Fabry Kidney Project and blood tests for both Gb3 dosage and genetic testing. Results: Among 1214 interviewed relatives, 115 (9.47%) were diagnosed with FD, with a predominance of women (66.10%). The most prevalent comorbidities were rheumatologic conditions and systemic hypertension (1.7% each), followed by heart, neurological, cerebrovascular diseases, and depression in 0.9% of individuals. Intolerance to physical exercise and tiredness were the most observed symptoms (1.7%), followed by periodic fever, intolerance to heat or cold, diffuse pain, burn sensation or numbness in hands and feet, reduced or absent sweating, as well as abdominal pain after meals in 0.9%. Conclusion: We found a prevalence of Fabry disease in 9.47% of relatives of CKD patients with this condition, remarkably with a 66.1% predominance of women, which contrasts with previous reports. The screening of family members of FD patients is important, since it can lead to early diagnosis and treatment, thus allowing better quality of life and improved clinical outcomes for these individuals.

RESUMO Introdução: A doença de Fabry é uma condição hereditária crônica, progressiva e multissistêmica, relacionada a uma mutação Xq22 no cromossomo X, que resulta em deficiência da enzima alfa-galactosidase, diminuindo a capacidade de degradação da globotriaosilceramida. Objetivos: avaliar a prevalência de mutações na doença de Fabry, bem como seus sinais e sintomas, em familiares de pacientes com doença renal crônica (DRC) diagnosticados com DF durante um estudo realizado anteriormente, denominado "Análise clínica e epidemiológica da doença de Fabry em centros de diálise no Brasil". Métodos: foi realizado um estudo transversal e os dados foram coletados através da entrevista com familiares de pacientes inscritos no Projeto Rim Fabry Brasil e exames de sangue para dosagem de Gb3 e testes genéticos. Resultados: Dos 1,214 familiares entrevistados, 115 (9,47%) foram diagnosticados com DF, com predomínio de mulheres (66,10%). As comorbidades mais prevalentes foram condições reumatológicas e hipertensão arterial sistêmica (1,7% cada), seguidas por doenças cardíacas, neurológicas, cerebrovasculares e depressão em 0,9% dos indivíduos. Intolerância ao exercício físico e cansaço foram os sintomas mais observados (1,7%), seguidos de febre periódica, intolerância ao calor ou ao frio, dor difusa, sensação de queimação ou dormência nas mãos e nos pés, sudorese reduzida ou ausente, além de dor abdominal após refeições em 0,9%. Conclusão: Encontramos uma prevalência da doença de Fabry em 9,47% dos familiares de pacientes com DRC com essa condição, notadamente com uma predominância de 66,1% de mulheres, o que contrasta com relatos anteriores. A triagem de familiares de pacientes com DF é importante, pois pode levar ao diagnóstico e tratamento precoces, permitindo melhor qualidade de vida e melhores resultados clínicos para esses indivíduos.

Downregulation of megalin, cubilin, ClC-5 and podocin in Fabry nephropathy: potential implications in the decreased effectiveness of enzyme replacement therapy.

Fabry disease is an X-linked disorder due to mutations in α-galactosidase A, resulting in the accumulation of enzyme substrates and cell malfunction. Kidney involvement is frequent, affecting all native kidney cell types. Podocyte damage results in proteinuria and chronic kidney disease. End-stage kidney disease is the rule in middle-aged males and some females with the classic phenotype. In podocytes and kidney proximal tubular cells, megalin is one of the molecules involved in enzyme replacement therapy (ERT) cellular absorption. After podocyte damage, podocin concentration is decreased and contributes to progressive proteinuria. We report in a male and a female patient the decreased expression of megalin, cubilin, ClC-5 and podocin compared to controls and chronic kidney disease (CKD) biopsies. Moreover, the decrease in ClC-5, a molecule engaged in endosomal-lysosomal acidification, could also affect ERT. These findings may partially explain some of the dysfunctions described in Fabry nephropathy and could highlight possible alterations in the pharmacokinetics of the delivered enzyme.

Screening of family members of chronic kidney disease patients with Fabry disease mutations: a very important and underrated task.

INTRODUCTION: Fabry disease is a chronic, progressive, and multi-system hereditary condition, related to an Xq22 mutation in X chromosome, which results in deficiency of alpha-galactosidase enzyme, hence reduced capacity of globotriaosylceramide degradation. OBJECTIVES: to evaluate the prevalence of Fabry disease (FD) mutations, as well as its signs and symptoms, among relatives of chronic kidney disease (CKD) patients diagnosed with FD during a previously conducted study, named "Clinical and epidemiological analysis of Fabry disease in dialysis centers in Brazil". METHODS: a cross-sectional study was carried out, and data was collected by interviewing the relatives of patients enrolled in the Brazil Fabry Kidney Project and blood tests for both Gb3 dosage and genetic testing. RESULTS: Among 1214 interviewed relatives, 115 (9.47%) were diagnosed with FD, with a predominance of women (66.10%). The most prevalent comorbidities were rheumatologic conditions and systemic hypertension (1.7% each), followed by heart, neurological, cerebrovascular diseases, and depression in 0.9% of individuals. Intolerance to physical exercise and tiredness were the most observed symptoms (1.7%), followed by periodic fever, intolerance to heat or cold, diffuse pain, burn sensation or numbness in hands and feet, reduced or absent sweating, as well as abdominal pain after meals in 0.9%. CONCLUSION: We found a prevalence of Fabry disease in 9.47% of relatives of CKD patients with this condition, remarkably with a 66.1% predominance of women, which contrasts with previous reports. The screening of family members of FD patients is important, since it can lead to early diagnosis and treatment, thus allowing better quality of life and improved clinical outcomes for these individuals.

When Frequent (Pandemic) Occurs in a Non-Frequent Disease: COVID-19 and Fabry Disease: Report of Two Cases.

Fabry disease (FD), like COVID-19, can affect multiple organs, including the lungs. Patients with FD are expected to develop severe COVID-19, due to involvement of not only the lungs but also the kidneys and the presence of other comorbidities. We present 2 cases of mild COVID-19 in patients with FD who were infected with the COVID-19 virus. Although it is unknown whether the X chromosome mutation in patients with FD affects the development of severe COVID-19, it is suggested that it may play a protective role against COVID-19 infection. Based on these cases, we suggest that FD is not a risk factor for severe COVID-19.

Fabry disease: GLA deletion alters a canonical splice site in a family with neuropsychiatric manifestations.

Fabry disease (FD) is a rare X-linked glycosphingolipidosis caused by mutations in GLA, a gene responsible for encoding α-galactosidase A, an enzyme required for degradation of glycosphingolipids, mainly globotriaosylceramide (Gb3) in all cells of the body. FD patients present a broad spectrum of clinical phenotype and many symptoms are shared with other diseases, making diagnosis challenging. Here we describe a novel GLA variant located in the 5' splice site of the intron 3, in four members of a family with neuropsychiatric symptoms. Analysis of the RNA showed the variant promotes alteration of the wild type donor site, affecting splicing and producing two aberrant transcripts. The functional characterization showed absence of enzymatic activity in cells expressing both transcripts, confirming their pathogenicity. The family presents mild signs of FD, as angiokeratoma, cornea verticillata, acroparesthesia, tinnitus, vertigo, as well as accumulation of plasma lyso-Gb3 and urinary Gb3. Interestingly, the man and two women present psychiatric symptoms, as depression or schizophrenia. Although psychiatric illnesses, especially depression, are frequently reported in patients with FD and studies have shown that the hippocampus is an affected brain structure in these patients, it is not clear whether the Gb3 accumulation in the brain is responsible for these symptoms or they are secondary. Therefore, new studies are needed to understand whether the accumulation of Gb3 could produce neuronal alterations leading to psychiatric symptoms.

Upregulation of ASIC1a channels in an in vitro model of Fabry disease.

Neuropathic pain is one of the key features of the classical phenotype of Fabry disease (FD). Acid sensing ion channels (ASICs) are H+-gated cation channels, which belong to the epithelial sodium channel/DeGenerin superfamily, sensitive to the diuretic drug Amiloride. Molecular cloning has identified several distinct ASIC subunits. In particular the ASIC1a subunit has been associated to pain and its upregulation has been documented in animal models of pain. We analyzed the expression of ASIC1a channels in cellular models that mimic the accumulation of glycosphingolipids in FD (FD-GLs) like Gb3, and LysoGb3. We used mouse primary neurons from brain cortex and hippocampus -supraspinal structures that accumulate FD-GLs-, as well as HEK293 cells. Incubation with Gb3, lysoGb3 and the inhibitor (1-deoxy-galactonojirymicin, DJG) of the enzyme α-galactosidase A (Gla) lead to the upregulation of ASIC1a channels. In addition, activation of ASIC1a results in the activation of the MAPK ERK pathway, a signaling pathway associated with pain. Moreover, accumulation of glycosphingolipids results in activation of ERK, an effect that was prevented by blocking ASIC1a channels with the specific blocker Psalmotoxin. Our results suggest that FD-GLs accumulation and triggering of the ERK pathway via ASIC channels might be involved in the mechanism responsible for pain in FD, thus providing a new therapeutic target for pain relief treatment.

Rare inherited kidney diseases: an evolving field in Nephrology / Doenças renais hereditárias raras: um campo em evolução na Nefrologia

Abstract There are more than 150 different rare genetic kidney diseases. They can be classified according to diagnostic findings as (i) disorders of growth and structure, (ii) glomerular diseases, (iii) tubular, and (iv) metabolic diseases. In recent years, there has been a shift of paradigm in this field. Molecular testing has become more accessible, our understanding of the underlying pathophysiologic mechanisms of these diseases has evolved, and new therapeutic strategies have become more available. Therefore, the role of nephrologists has progressively shifted from a mere spectator to an active player, part of a multidisciplinary team in the diagnosis and treatment of these disorders. This article provides an overview of the recent advances in rare hereditary kidney disorders by discussing the genetic aspects, clinical manifestations, diagnostic, and therapeutic approaches of some of these disorders, named familial focal and segmental glomerulosclerosis, tuberous sclerosis complex, Fabry nephropathy, and MYH-9 related disorder.

Resumo As doenças renais genéticas raras compreendem mais de 150 desordens. Elas podem ser classificadas segundo achados diagnósticos como (i) distúrbios do crescimento e estrutura, (ii) doenças glomerulares, (iii) tubulares e (iv) metabólicas. Nos últimos anos, houve uma mudança de paradigma nesse campo. Os testes moleculares tornaram-se mais acessíveis, nossa compreensão sobre os mecanismos fisiopatológicos subjacentes a essas doenças evoluiu e novas estratégias terapêuticas foram propostas. Portanto, o papel do nefrologista mudou progressivamente de mero espectador a participante ativo, parte de uma equipe multidisciplinar, no diagnóstico e tratamento desses distúrbios. O presente artigo oferece um panorama geral dos recentes avanços a respeito dos distúrbios renais hereditários raros, discutindo aspectos genéticos, manifestações clínicas e abordagens diagnósticas e terapêuticas de alguns desses distúrbios, mais especificamente a glomeruloesclerose segmentar e focal familiar, complexo da esclerose tuberosa, nefropatia de Fabry e doença relacionada ao MYH9.

Rare inherited kidney diseases: an evolving field in Nephrology.

There are more than 150 different rare genetic kidney diseases. They can be classified according to diagnostic findings as (i) disorders of growth and structure, (ii) glomerular diseases, (iii) tubular, and (iv) metabolic diseases. In recent years, there has been a shift of paradigm in this field. Molecular testing has become more accessible, our understanding of the underlying pathophysiologic mechanisms of these diseases has evolved, and new therapeutic strategies have become more available. Therefore, the role of nephrologists has progressively shifted from a mere spectator to an active player, part of a multidisciplinary team in the diagnosis and treatment of these disorders. This article provides an overview of the recent advances in rare hereditary kidney disorders by discussing the genetic aspects, clinical manifestations, diagnostic, and therapeutic approaches of some of these disorders, named familial focal and segmental glomerulosclerosis, tuberous sclerosis complex, Fabry nephropathy, and MYH-9 related disorder.