[A3243G mitochondrial DNA mutation and heterogeneous phenotypic expression]

mitochondrial DNA (DNAmt) mutations are associated with several clinical manifestations affecting different systems. They are usually underdiagnosed even with the relatively high prevalence in certain populations. The diagnosis can be established on clinical data, histopathologic studies and biochemical abnormalities in the respiratory chain, or the finding of the specific causal mutation in the DNAmt.

we describe a patient and her family history, affecting neurologic, cardiovascular and endocrine systems. We established the diagnosis of MELAS syndrome (mitochondrial encephalomy-opathy, lactic acidosis and stroke-like episodes) with the collaboration of the Laboratory of Molecular Neurogenetics of the Department of Neurology of Columbia University in New York, NY, USA to whom we sent peripheral blood DNA. The DNA was amplified by polymerase chain reaction (PCR) and subjected to restriction fragment length polymorphism analysis. The study was positive for the point mutation adenine (A) for guanine (G) on the position 3243 of DNAmt. We make a brief clinical description. We also review DNAmt, related mutations and clinical expressions of the disease. We also highlighted the prevalence of DNAmt mutations in certain clinical situations.