PP03.6 – 2785: MELAS: Getting straight to the point!

Abstract

Background MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes) can present mimicking childhood stroke. Recognition of this condition enables rapid genetic diagnosis, obviating the need of extensive mitochondrial investigations including muscle biopsy. Case A previously well eight year old girl with normal development presented with a short history of fever and vomiting. She went on to develop encephalopathy and lethargy and was noted to have right sided weakness. Neurological examination demonstrated brisk reflexes on her right side. A brain MRI revealed extensive abnormal high signal in the left occipital and temporal lobes and left thalamus with no diffusion restriction. Serum and CSF lactate levels were elevated at 4.5 and 4.1 mmol/L respectively. A family history of cardiomyopathy and diabetes was elicited in her mother. A clinical diagnosis of MELAS was made at this stage. Serum mitochondrial DNA studies confirmed the presence of m.3243A>G mutation at a level of 96%. Subsequent investigations identified the same mutation in her mother at a level of 55%. Our patient made good clinical recovery and was discharged with neurometabolic follow-up. Discussion MELAS is a maternally inherited multisystem mitochondrial disorder with varying phenotypes. In contrast to ischaemic strokes, changes on brain imaging usually do not conform to the distribution of arteries and diffusion restriction is absent. Traditionally, the work-up of a suspected mitochondrial disorder involves muscle biopsy, which typically shows ragged red fibres in MELAS. However, this stage of investigation can now be avoided with the advent of molecular genetic testing as m.3243A>G mutations are responsible for 80% of cases of MELAS. Conclusion A diagnosis of MELAS should be suspected when a patient presents with the above constellation of signs and symptoms. Molecular genetic testing provides rapid confirmation and may avoid the need for unnecessary invasive investigations.