PSUN248 Mitochondrial diabetes - a rare but important cause of diabetes

BACKGROUND: Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) syndrome is a rare mitochondrial disorder which presents with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. Mitochondrial diabetes is the cause in 1% of all diabetic patients. Here we present a case of a patient with insulin dependent diabetes mellitus (DM) who experienced sensorineural deafness and was diagnosed with MELAS. CASE: 33-year-old female presented with stroke like symptoms in December 2018. Medical history was significant for Diabetes Mellitus (DM), bilateral deafness and end stage renal disease requiring peritoneal dialysis with subsequent kidney transplant. On presentation, she had left sided weakness, lab work revealed lactic acidosis. MRI brain showed large areas of restricted diffusion in right hemisphere and cerebral edema. CSF analysis was positive for lactate and pyruvate. Left lower extremity muscle biopsy and mitochondrial genome analysis were positive for m.3243A>G in the MT-TL1 with 80% heteroplasmy, confirming the diagnosis of MELAS. Patient was started on Arginine, CoQ10, Levetiracetam, phenytoin, IVIG and her symptoms improved. DM was diagnosed in 2013 when patient was on peritoneal dialysis. Family history significant for type 2 DM in maternal uncle. DISCUSSION: Mitochondrial diseases are rare, maternally inherited, heterogeneous conditions caused by mutations in mitochondrial DNA and present with a variety of clinical symptoms. Mitochondrial diabetes results from the 3243 A>G gene mutation, responsible for both MELAS and Mitochondrial inherited diabetes and deafness (MIDD). MELAS presents with encephalopathy, stroke like symptoms and lactic acidosis (1). MIDD presents with nerve deafness, which usually occurs at an early age (2). In our patient, she presented with neurological symptoms suggesting MELAS and bilateral deafness suggesting MIDD. Her presentation is unusual and constitutes an overlap between both disorders. CONCLUSION: Early recognition and diagnosis of mitochondrial diabetes is important. The diagnosis has important genetic implications for other family members. This case report highlights the presentation of MELAS and MIDD and importance of genetic studies in the confirmation of diagnosis 1) D. M. Sproule and P. Kaufmann, "Mitochondrial encephalopathy, lactic acidosis, and strokelike episodes: basic concepts, clinical phenotype, and therapeutic management of MELAS syndrome," Annals of the New York Academy of Sciences, vol. 1142, pp. 133–158, 20082) Murphy R, Turnbull DM, Walker M, Hattersley AT. Clinical features, diagnosis and management of maternally inherited diabetes and deafness (MIDD) associated with the 3243A>G mitochondrial point mutation. Diabetic Medicine 2008. Apr;25(4): 383-99. doi: 10.1111/j.1464-5491.2008.02359.x.Epub 2008 Feb 18. PMID: 18294221. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.