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Abstract Introduction: Membranoproliferative glomerulonephritis (MPGN) is a rare glomerular disease with a variable prognosis. A new classification based on the presence or absence of immunoglobulins and complement deposits in immunofluorescence microscopy (IF) of kidney biopsy has recently been proposed. The objectives of the study were to determine and compare the clinical, laboratory, and histopathological characteristics of those with primary or secondary MPGN, reclassify the primary ones based on IF findings, and evaluate kidney outcomes. Methods: This was an observational retrospective cohort study carried out in a single center (UNIFESP), based on the data collected from medical records of patients followed from 1996 to 2019. Results: Of 53 cases of MPGN, 36 (67.9%) were classified as primary and 17 (32.1%) as secondary MPGN. Most patients were hypertensive (84.9%) and had edema (88.7%) and anemia (84.9%); 33 (91.7%) patients classified as primary MPGN were reclassified as immune-complex-mediated and 3 (8.3%) as complement-mediated. The secondary MPGN group had hematuria more frequently (p <0.001) and a higher prevalence of deposits of IgG (p = 0.02) and C1q (p = 0.003). Regarding the outcome, 39% of the patients achieved partial or complete remission. Lower initial serum albumin and higher initial 24-hour proteinuria were factors associated with worst renal prognosis. Conclusions: According to the new histological classification, the vast majority of MPGN cases were classified as being mediated by immune complexes. There were few differences between primary and secondary MPGN in relation to their clinical and laboratory characteristics.
Resumo Introdução: Glomerulonefrite membranoproliferativa (GNMP) é uma doença glomerular rara com prognóstico variável. Recentemente, foi proposta uma nova classificação baseada na presença ou ausência de imunoglobulinas e depósitos de complemento na microscopia de imunofluorescência (IF) da biópsia renal. Os objetivos do estudo foram determinar e comparar as características clínicas, laboratoriais e histopatológicas daqueles com GNMP primária ou secundária, reclassificar as primárias com base em achados da IF e avaliar os desfechos renais. Métodos: Este foi um estudo de coorte observacional retrospectivo realizado em centro único (UNIFESP), com base nos dados coletados de prontuários de pacientes acompanhados de 1996 a 2019. Resultados: Dos 53 casos de GNMP, 36 (67,9%) foram classificados como GNMP primária e 17 (32,1%) como GNMP secundária. A maioria dos pacientes era hipertensa (84,9%) e apresentava edema (88,7%) e anemia (84,9%); 33 (91,7%) pacientes classificados como GNMP primária foram reclassificados como mediados por imunocomplexo e 3 (8,3%) como mediados por complemento. O grupo de GNMP secundária apresentou mais frequentemente hematúria (p <0,001) e maior prevalência de depósitos de IgG (p = 0,02) e C1q (p = 0,003). Com relação ao desfecho, 39% dos pacientes alcançaram remissão parcial ou completa. Albumina sérica inicial mais baixa e proteinúria de 24 horas inicial mais elevada foram fatores associados a pior prognóstico renal. Conclusões: De acordo com a nova classificação histológica, a grande maioria dos casos de GNMP foram classificados como sendo mediados por imunocomplexos. Houve poucas diferenças entre GNMP primária e secundária em relação às suas características clínicas e laboratoriais.
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SUMMARY Fabry disease (FD) is a recessive monogenic inheritance disease linked to chromosome X, secondary to mutations in the GLA gene. Its prevalence is estimated between 1:8,454 and 1:117,000 among males and is probably underdiagnosed. Mutations in the GLA gene lead to the progressive accumulation of globotriaosylceramide (Gb3). Gb3 accumulates in lysosomes of different types of cells of the heart, kidneys, skin, eyes, central nervous system, and gastrointestinal system, and may lead to different clinical scenarios. The onset of symptoms occurs during childhood, with acroparesthesia, heat intolerance, and gastrointestinal symptoms, such as nausea, vomiting, abdominal pain, and neuropathic pain. Subsequently, symptoms related to progressive impairment appear, such as angiokeratomas, cornea verticillata, left ventricular hypertrophy, myocardial fibrosis, proteinuria, and renal insufficiency. The latter being the main cause of death in FD. The gold standard for diagnosis is the genetic analysis in search of mutation, in addition to family history. In homozygous patients, the enzyme activity can also be used. Once the diagnosis is confirmed, the patient and their family should receive genetic counseling. The treatment, in turn, currently focuses mainly on replacing the enzyme that is absent or deficient by means of enzyme replacement therapy, with the purpose of avoiding or removing deposits of Gb3. Chaperones can also be used for the treatment of some cases. It is considered that the specific treatment should be initiated as soon as a diagnosis is obtained, which can change the prognosis of the disease.