Infrared spectroscopy as a new approach for early fabry disease screening: a pilot study.

BACKGROUND: Fabry disease (FD) is a rare X-linked lysosomal storage disorder marked by alpha-galactosidase-A (α-Gal A) deficiency, caused by pathogenic mutations in the GLA gene, resulting in the accumulation of glycosphingolipids within lysosomes. The current screening test relies on measuring α-Gal A activity. However, this approach is limited to males. Infrared (IR) spectroscopy is a technique that can generate fingerprint spectra of a biofluid's molecular composition and has been successfully applied to screen numerous diseases. Herein, we investigate the discriminating vibration profile of plasma chemical bonds in patients with FD using attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy. RESULTS: The Fabry disease group (n = 47) and the healthy control group (n = 52) recruited were age-matched (39.2 ± 16.9 and 36.7 ± 10.9 years, respectively), and females were predominant in both groups (59.6% and 65.4%, respectively). All patients had the classic phenotype (100%), and no late-onset phenotype was detected. A generated partial least squares discriminant analysis (PLS-DA) classification model, independent of gender, allowed differentiation of samples from FD vs. control groups, reaching 100% sensitivity, specificity and accuracy. CONCLUSION: ATR-FTIR spectroscopy harnessed to pattern recognition algorithms can distinguish between FD patients and healthy control participants, offering the potential of a fast and inexpensive screening test.

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.

What should rheumatologists know about Gaucher disease and Fabry disease? Connecting the dots for an overview.

Gaucher and Fabry diseases are lysosomal storage disorders in which deficient enzyme activity leads to pathological accumulation of sphingolipids. These diseases have a broad phenotypic presentation. Musculoskeletal symptoms and pain complaints are frequently reported by patients. Thus, rheumatologists can be contacted by these patients, contributing to the correct diagnosis, earlier indication of appropriate treatment and improvement of their prognosis. This review describes important concepts about Gaucher and Fabry diseases that rheumatologists should understand to improve patients' quality of life and change the natural history of these diseases.

Differences Between Two Distinct Hypertrophic Cardiac Conditions: Fabry Disease versus Hypertrophic Cardiomyopathy. / Diferenças entre Duas Condições Cardíacas Hipertróficas Distintas: Doença de Fabry Versus Cardiomiopatia Hipertrófica.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) and Fabry disease (FD) are genetically inherited diseases with left ventricular hypertrophy (LVH) phenotype characteristics that cause adverse cardiac outcomes. OBJECTIVES: To investigate the demographic, clinical, biochemical, electrocardiographic (ECG), and echocardiographic (ECHO) differences between HCM and FD. METHODS: 60 HCM and 40 FD patients were analyzed retrospectively as a subanalysis of the 'LVH-TR study' after excluding patients with atrial fibrillation, pace rhythm, bundle branch blocks, and second and third-degree atrioventricular (AV) blocks. The significance level was accepted as <0.05. RESULTS: Male gender (p=0.048) and creatinine (p=0.010) are significantly higher in favor of FD; however, ST depression (p=0.028), QT duration (p=0.041), interventricular septum thickness (IVSd) (p=0.003), posterior wall thickness (PWd) (p=0.009), moderate-severe mitral regurgitation (MR) (p=0.013), and LV mass index (LVMI) (p=0.041) are significantly higher in favor of HCM in the univariate analyses. In multivariate analysis, statistical significance only continues in creatinine (p=0.018) and QT duration (0.045). FD was positively correlated with creatinine (rho=0.287, p=0.004) and HCM was positively correlated with PWd (rho=0.306, p=0.002), IVSd (rho=0.395, p<0.001), moderate-severe MR (rho=0.276, p<0.005), LVMI (rho=0.300, p=0.002), relative wall thickness (RWT) (rho=0.271, p=0.006), QT duration (rho=0.213, p=0.034) and ST depression (rho=0.222, p=0.026). CONCLUSION: Specific biochemical, ECG, and ECHO characteristics can aid in the differentiation and early diagnosis of HCM and FD.

FUNDAMENTO: A cardiomiopatia hipertrófica (CMH) e a doença de Fabry (DF) são doenças herdadas geneticamente com características fenotípicas de hipertrofia ventricular esquerda (HVE) que causam resultados cardíacos adversos. OBJETIVOS: Investigar as diferenças demográficas, clínicas, bioquímicas, eletrocardiográficas (ECG) e ecocardiográficas (ECO) entre CMH e DF. MÉTODOS: 60 pacientes com CMH e 40 pacientes com DF foram analisados retrospectivamente como uma subanálise do "estudo LVH-TR" após exclusão de pacientes com fibrilação atrial, ritmo de estimulação, bloqueios de ramo e bloqueios atrioventriculares (AV) de segundo e terceiro graus. O nível de significância foi aceito como <0,05. RESULTADOS: O sexo masculino (p=0,048) e a creatinina (p=0,010) são significativamente maiores a favor da DF; entretanto, infradesnivelamento do segmento ST (p=0,028), duração do QT (p=0,041), espessura do septo interventricular (SIVd) (p=0,003), espessura da parede posterior (PWd) (p=0,009), insuficiência mitral moderada a grave (IM) (p=0,013) e o índice de massa ventricular esquerda (IMVE) (p=0,041) são significativamente maiores a favor da CMH nas análises univariadas. Na análise multivariada, a significância estatística apenas permanece na creatinina (p=0,018) e na duração do intervalo QT (0,045). A DF foi positivamente correlacionada com a creatinina (rho=0,287, p=0,004) e a CMH foi positivamente correlacionada com o PWd (rho=0,306, p=0,002), IVSd (rho=0,395, p<0,001), IM moderada-grave (rho= 0,276, p<0,005), IMVE (rho=0,300, p=0,002), espessura relativa da parede (ERP) (rho=0,271, p=0,006), duração do QT (rho=0,213, p=0,034) e depressão do segmento ST (rho =0,222, p=0,026). CONCLUSÃO: Características bioquímicas, ECG e ECO específicas podem auxiliar na diferenciação e no diagnóstico precoce da CMH e da DF.

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.

Pilot study of newborn screening for six lysosomal diseases in Brazil.

BACKGROUND: Lysosomal diseases (LDs) are progressive life-threatening disorders that are usually asymptomatic at birth. Specific treatments are available for several LDs, and early intervention improves patient's outcomes. Thus, these diseases benefit from newborn screening (NBS). We have performed a pilot study for six LDs in Brazil by tandem mass spectrometry. METHODS: Dried blood spot (DBS) samples of unselected newborns were analyzed by the Neo-LSD™ kit (Perkin-Elmer) by MS/MS. Samples with low enzyme activity were submitted to the evaluation of specific biomarkers by ultra-performance liquid chromatography tandem-mass spectrometry as the second-tier, and were analyzed by a next-generation sequencing (NGS) multi-gene panel as the third-tier. All tests were performed in the same DBS sample. RESULTS: In 20,066 newborns analyzed, 15 samples showed activity of one enzyme below the cutoff. Two newborns had biochemical and molecular results compatible with Fabry disease, and five newborns had biochemical results and pathogenic variants or variants of unknown significance (VUS) in GAA. CONCLUSIONS: This study indicates that the use of enzyme assay as the first-tier test gives an acceptably low number of positive results that requires second/third tier testing. The possibility to run all tests in a DBS sample makes this protocol applicable to large-scale NBS programs.

Enfermedad de Fabry: revisión para el cardiólogo clínico / Fabry disease: review for the clinical cardiologist / Doença de Fabry: revisão para o cardiologista clínico

La enfermedad de Fabry es una afección genética producida por un déficit total o parcial de la enzima alfagalactosidasa A implicada en el catabolismo de glicoesfingolípidos. Dicha alteración genera el depósito lisosomal del residuo globotriasilceramida (Gb-3) a nivel multitisular, a predominio de los sistemas renal, cardíaco, nervioso y cutáneo. Debido a su baja prevalencia y su variada presentación clínica representa un verdadero reto diagnóstico. La combinación de antecedentes familiares de cardiopatía y afección renal, diferentes grados de hipertrofia del ventrículo izquierdo, sumado a afecciones cutáneas, neurológicas y enfermedad renal progresiva, deben hacer plantear la posibilidad de una enfermedad de Fabry. El cardiólogo que estudia un paciente con hipertrofia ventricular es quien debe sospecharla, y debe hacer un diagnóstico diferencial con miocardiopatías hipertróficas, cardiopatía hipertensiva u otras miocardiopatías por depósitos. Los aportes diagnósticos de la resonancia magnética cardíaca han sido de suma importancia en los últimos años. Los estudios enzimáticos y genéticos, antes de muy difícil adquisición en nuestro medio, son factibles en la actualidad. Un diagnóstico temprano es clave para iniciar el tratamiento enzimático sustitutivo, evitar un daño más extenso e irreversible, e identificar los familiares afectados en fases iniciales.

Fabry disease is a genetic condition caused by a total or partial deficiency of the enzyme alphagalactosidase A involved in the catabolism of glycosphingolipids. This alteration generates the lysosomal deposit of the globotriasylceramide residue (Gb-3) at the multi-tissue level, predominantly in the kidneys, heart, nervous system and skin. Due to its low prevalence and its varied clinical presentation, it represents a true diagnostic challenge. The combination of family history of heart disease and kidney disease, different degrees of hypertrophy of the left ventricle, added to skin and neurological conditions and progressive kidney disease, should raise the possibility of Fabry disease. The cardiologist who studies a patient with ventricular hypertrophy is the one who should suspect it and make a differential diagnosis of hypertrophic cardiomyopathies, hypertensive heart disease or other cardiomyopathies due to deposits. Diagnostic complementation with a cardiac resonance study has been extremely important in recent years. Enzymatic and genetic studies, previously very difficult to acquire in our environment, are currently feasible. An early diagnosis is key to starting enzyme replacement therapy, avoiding more extensive and irreversible damage, and allowing affected family members to be identified in the early stages.

A doença de Fabry é uma condição genética causada por uma deficiência total ou parcial da enzima alfagalactosidase A envolvida no catabolismo de glicoesfingolipídeos. Essa alteração gera o depósito lisossomal do resíduo globotriasilceramida (Gb-3) em nível multitecidual, predominantemente nos rins, coração, sistema nervoso e pele. Devido à sua baixa prevalência e à sua apresentação clínica variada, representa um verdadeiro desafio diagnóstico. A combinação de história familiar de cardiopatia e doença renal, diferentes graus de hipertrofia do ventrículo esquerdo, somada a condições dermatológicas e neurológicas e doença renal progressiva, deve levantar a possibilidade de doença de Fabry. O cardiologista que estuda um paciente com hipertrofia ventricular é quem deve suspeitar e fazer um diagnóstico diferencial de cardiomiopatias hipertróficas, cardiopatias hipertensivas ou outras cardiomiopatias por depósitos. A complementação diagnóstica com estudo de ressonância cardíaca tem sido de extrema importância nos últimos anos. Estudos enzimáticos e genéticos, anteriormente muito difíceis de adquirir em nosso meio, são atualmente viáveis. O diagnóstico precoce é fundamental para iniciar a terapia de reposição enzimática, para evitar danos mais extensos e irreversíveis, e permite que os familiares afetados sejam identificados nos estágios iniciais.

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) / Recomendações para o diagnóstico e manejo de pacientes pediátricos com doença de Fabry: documento do comitê de doenças raras da Sociedade Brasileira de Nefrologia (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.

A doença de Fabry (DF) é uma doença genética, com herança ligada ao cromossomo X, devido a variantes no gene GLA que codifica a enzima α-galactosidase A (α-GAL). O propósito do presente estudo foi criar um consenso objetivando padronizar as recomendações em relação ao acometimento renal da DF com orientações sobre o diagnóstico, rastreamento, e tratamento de pacientes pediátricos. Esse consenso é uma iniciativa do Comitê de Doenças Raras (Comdora) da Sociedade Brasileira de Nefrologia (SBN). Foram considerados para esta revisão estudos clínicos controlados randomizados e estudos com dados de vida real somados à experiência dos autores. O resultado desse consenso foi auxiliar no gerenciamento das expectativas de pacientes e médicos quanto aos resultados do tratamento. Assim, este documento de consenso recomenda a investigação dos familiares pediátricos de um caso índice, assim como de casos com clínica sugestiva. A partir do diagnóstico, avaliar todos os possíveis acometimentos da DF e graduar através de escalas. A partir de uma revisão extensa da literatura incluindo protocolos pediátricos e avaliando particularmente os casos pediátricos de estudos gerais, pode-se concluir que os benefícios do tratamento precoce são grandes, principalmente quanto aos parâmetros de dor neuropática e do acometimento renal, e suplantam os possíveis adversos que foram sobretudo manifestados por reações infusionais.

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.

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.

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.

Higher rate of rheumatic manifestations and delay in diagnosis in Brazilian Fabry disease patients.

BACKGROUND: Fabry disease (FD) is an X-linked lysosomal disorder due to mutations in the GLA gene resulting in defective enzyme alpha-galactosidase A. FD patients are frequently misdiagnosed, commonly for rheumatic diseases. Determining pathogenicity of a mutation depends of in silico predictions but mostly on available clinical information and interpretation may change in light of evolving knowledge. Similar signs and symptoms in carriers of GLA gene genetic variants of unknown significance or of benign variants may hamper diagnosis. This study reviews rheumatic and immune-mediated manifestations in a cohort of Brazilian FD patients with classic mutations and also in subjects with GLA gene A143T and R118C mutations. Misdiagnoses, time to correct diagnosis or determination of GLA gene status, time to treatment initiation and reasons for treatment prescription in A143T and R118C subjects are reviewed. METHODS: Genotype confirmed classic FD patients (n = 37) and subjects with GLA gene mutations A143T and R118C (n = 19) were referred for assessment. Subjects with R118C and A143T mutations had been previously identified during screening procedures at hemodialysis units. All patients were interviewed and examined by a rheumatologist with previous knowledge of disease and/or mutation status. A structured tool developed by the authors was used to cover all aspects of FD and of common rheumatic conditions. All available laboratory and imaging data were reviewed. RESULTS: Thirty-seven consecutive FD patients were interviewed - 16 male / 21 female (mean age: 43.1 years) and 19 consecutive subjects with GLA gene mutations R118C and A143T were evaluated - 8 male / 11 female (mean age: 39.6 years); 15 [R118C] / 4 [A143T]. Misdiagnosis in FD patients occurred in 11 males (68.8%) and 13 females (61.9%) of which 10 males and 9 females were previously diagnosed with one or more rheumatic conditions, most frequently rheumatic fever or "rheumatism" (unspecified rheumatic disorder). Median time for diagnosis after symptom onset was 16 years (range, 0-52 years). Twenty-two patients were treated with enzyme replacement therapy (ERT) - 13 male and 9 female. Median time to ERT initiation after FD diagnosis was 0.5 years (range, 0-15 years). Rheumatic manifestations occurred in 68.4% of R118C and A143T subjects. Two subjects had been prescribed ERT because of renal disease [R118C] and neuropsychiatric symptoms [A143T]. CONCLUSION: Misdiagnoses occurred in 64.8% of FD patients, most frequently for rheumatic conditions. Median time for correct diagnosis was 16 years. Rheumatic manifestations are also frequent in subjects with GLA gene R118C and A143T mutations. These results reinforce the need to raise awareness and increase knowledge about Fabry disease among physicians, notably rheumatologists, who definitely have a role in identifying patients and determining disease burden. Decision to start treatment should consider expert opinion and follow local guidelines.

Higher rate of rheumatic manifestations and delay in diagnosis in Brazilian Fabry disease patients

Abstract Background: Fabry disease (FD) is an X-linked lysosomal disorder due to mutations in the GLA gene resulting in defective enzyme alpha-galactosidase A. FD patients are frequently misdiagnosed, commonly for rheumatic diseases. Determining pathogenicity of a mutation depends of in silico predictions but mostly on available clinical information and interpretation may change in light of evolving knowledge. Similar signs and symptoms in carriers of GLA gene genetic variants of unknown significance or of benign variants may hamper diagnosis. This study reviews rheumatic and immune-mediated manifestations in a cohort of Brazilian FD patients with classic mutations and also in subjects with GLA gene A143T and R118C mutations. Misdiagnoses, time to correct diagnosis or determination of GLA gene status, time to treatment initiation and reasons for treatment prescription in A143T and R118C subjects are reviewed. Methods: Genotype confirmed classic FD patients (n = 37) and subjects with GLA gene mutations A143T and R118C (n = 19) were referred for assessment. Subjects with R118C and A143T mutations had been previously identified during screening procedures at hemodialysis units. All patients were interviewed and examined by a rheumatologist with previous knowledge of disease and/or mutation status. A structured tool developed by the authors was used to cover all aspects of FD and of common rheumatic conditions. All available laboratory and imaging data were reviewed. Results: Thirty-seven consecutive FD patients were interviewed - 16 male / 21 female (mean age: 43.1 years) and 19 consecutive subjects with GLA gene mutations R118C and A143T were evaluated - 8 male / 11 female (mean age: 39.6 years); 15 [R118C] / 4 [A143T]. Misdiagnosis in FD patients occurred in 11 males (68.8%) and 13 females (61.9%) of which 10 males and 9 females were previously diagnosed with one or more rheumatic conditions, most frequently rheumatic fever or "rheumatism" (unspecified rheumatic disorder). Median time for diagnosis after symptom onset was 16 years (range, 0-52 years). Twenty-two patients were treated with enzyme replacement therapy (ERT) - 13 male and 9 female. Median time to ERT initiation after FD diagnosis was 0.5 years (range, 0-15 years). Rheumatic manifestations occurred in 68.4% of R118C and A143T subjects. Two subjects had been prescribed ERT because of renal disease [R118C] and neuropsychiatric symptoms [A143T]. Conclusion: Misdiagnoses occurred in 64.8% of FD patients, most frequently for rheumatic conditions. Median time for correct diagnosis was 16 years. Rheumatic manifestations are also frequent in subjects with GLA gene R118C and A143T mutations. These results reinforce the need to raise awareness and increase knowledge about Fabry disease among physicians, notably rheumatologists, who definitely have a role in identifying patients and determining disease burden. Decision to start treatment should consider expert opinion and follow local guidelines.(AU)