ABSTRACT
Background: Atypical hemolytic uremic syndrome (aHUS) is an ultra-rare disease. Therefore, studies involving large samples are scarce, making registries powerful tools to evaluate cases. We present herein the first analysis of the Brazilian aHUS Registry (BRaHUS). Methods: Analysis of clinical, laboratory, genetic and treatment data from patients inserted in the BRaHUS, from 2017 to 2020, as an initiative of the Rare Diseases Committee of the Brazilian Society of Nephrology. Results: The cohort consisted of 75 patients (40 adults and 35 pediatric). There was a predominance of women (56%), median age at diagnosis of 20.7 years and a positive family history in 8% of cases. Renal involvement was observed in all cases and 37% had low C3 levels. In the <2 years of age group, males were predominant. Children presented lower levels of hemoglobin (P = .01) and platelets (P = .003), and higher levels of lactate dehydrogenase (LDH) (P = .004) than adults. Genetic analysis performed in 44% of patients revealed pathogenic variants in 66.6% of them, mainly in CFH and the CFHR1-3 deletion. Plasmapheresis was performed more often in adults (P = .005) and 97.3% of patients were treated with eculizumab and its earlier administration was associated with dialysis-free after 3 months (P = .08). Conclusions: The cohort of BRaHUS was predominantly composed of female young adults, with renal involvement in all cases. Pediatric patients had lower hemoglobin and platelet levels and higher LDH levels than adults, and the most common genetic variants were identified in CFH and the CFHR1-3 deletion with no preference of age, a peculiar pattern of Brazilian patients.
ABSTRACT
BACKGROUND/AIMS: Fabry disease (FD), an X-linked lysosomal storage disorder, leads to accumulation of globotriaosylceramide. Screening in dialysis patients may identify genetic variants of unknown clinical significance. We aimed to characterize the pathogenicity of a novel GLA gene mutation identified during hemodialysis screening and the histologic findings of early Fabry nephropathy. METHODS: One out of 108 male hemodialysis patients screened for FD presented low α-galactosidase A activity. A novel missense mutation (p.G35V) in the GLA gene was detected. Family screening identified 11 additional cases (8 women). Clinical investigation was conducted in 10 patients (index case and 9 relatives). Pathogenicity of the new mutation was investigated by clinical and laboratory tests, cardiac and cranial magnetic resonance imaging, and kidney biopsy. RESULTS: Cardiac manifestations were detected in most patient from both genders, such as left ventricular hypertrophy and short PR interval. White matter lesion was present in 3 women. Pulvinar lesion of the thalamus and ischemic stroke were detected in male patients. Abnormal glomerular filtration rate (GFR) and/or albuminuria were present in 5 patients (3 women). Renal biopsies (n = 7) revealed globotriaosylceramide deposits in different cell types and foot processes effacement in all patients, including women with normal albuminuria. Despite a normal GFR, tubulointerstitial fibrosis ranging from 5 to 20% was present in young women and men with normal or high albuminuria, respectively. CONCLUSION: The novel missense mutation p.G35V leads to severe systemic manifestations of FD in men and women. Kidney histological changes, including tubulointerstitial fibrosis, may predate albuminuria and GFR changes in adult women. Novel non-invasive markers are required for early detection of Fabry nephropathy.
