Kidney involvement in MELAS syndrome: Description of 2 cases

Abstract

Introduction: MELAS syndrome -myopathy, encephalopathy, lactic acidosis and stroke-like episodes- is a maternally-inherited mitochondrial cytopathy related to several mitochondrial DNA mutations, with the A3243G mutation in tRNA^Leu gene being the most frequent of them.

Patients and methods: Apart from its typical symptomatology, patients usually exhibit a maternally-inherited history of neurosensory deafness and insulin-dependent type 2 diabetes mellitus (T2DM). Recent studies have shown that few patients carrying a A3243G mutation also suffer from renal dysfunction, usually in form of focal segmental glomerulosclerosis (FSGS).

Results: In this study we examine kidney involvement in 2 unrelated patients with a A3243G mutation by genetic testing. Both have a maternally-inherited neurosensory deafness and insulin-dependent T2DM. A renal biopsy was performed in both patients. One patient developed nephrotic proteinuria and renal insufficiency, with FSGS findings being observed in the kidney biopsy, whereas the other suffered from mild proteinuria and renal insufficiency, with non-specific glomerular changes.

Conclusion: The presence of FSGS or other kidney involvement accompanied by hereditary neurosensory deafness and T2DM could be suggestive of a A3243G tRNA^Leu mutation and should prompt a genetic testing and an evaluation of potential extrarenal involvement.

Keywords: A3243G mutation; Chronic kidney disease; Citopatía mitocondrial; Focal segmental glomerulosclerosis; Glomeruloesclerosis focal segmentaria; Insuficiencia renal crónica; Mitochondrial cythopathy; Mutación A3243G.