Novel Mitochondrial Cytopathy Causing Mitochondrial Encephalomyopathy With Lactic Acidosis and Stroke-Like Episodes Syndrome and Tubulointerstitial Nephropathy.

Mitochondrial cytopathies, predominantly MT-TL1 mutations and, to a lesser extent, MT-ND5, have been associated with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), manifesting as multi-organ dysfunction. This is just the second instance of MELAS secondary to the pathogenic novel m.13091T>C variant of MT-ND5. Moreover, nephropathy associated with MT-ND5 mutation has only been reported in nine cases so far. A middle-aged man presented in a state of acute confusion with speech difficulty with both receptive and expressive aphasia. He had a background of refractory seizures, chronic atypical migraine, childhood-onset optic neuropathy, and end-stage renal disease requiring renal transplant. During admission, he had episodes of aggression and paranoid beliefs. Magnetic resonance (MR) imaging of the head showed multiple areas of cortical abnormality, unusual for age, including a large frontal infarct crossing arterial boundaries. Cerebrospinal fluid (CSF) protein and lactate were high, whereas, the electroencephalography (EEG) result was normal. Muscle biopsy mitochondrial DNA gene sequencing derived novel MT-ND5 gene variant m.13091T>C p.(Met252Thr). Kidney biopsy previously had shown interstitial fibrosis and tubular atrophy. He was managed as acute ischaemic stroke along with a combination of clobazam, levetiracetam, and eslicarbazepine for seizures. MELAS typically presents with seizures, stroke-like episodes, cortical visual loss, and recurrent migraine headaches. The previous reported case of m.13091T>C mutation followed a similar progression, however, there was no associated nephropathy and normal visual acuity. Kidney transplants in affected patients of MELAS have been associated with a high survival rate. MT-ND5 mutation-associated nephropathy has shown a variable manifestation, either as focal segmental glomerular sclerosis (FSGS) or tubulo-interstitial disease.
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