Lactic Acidosis, Hypotension, and Sensorineural Hearing Loss Following Intentional Metformin Overdose

Abstract Introduction: Maternally inherited diabetes and deafness (MIDD) is a multisystem disorder characterized by insulinopenia and sensorineural hearing loss. This rare form of monogenic diabetes is most commonly associated with the A3243G mutation of mitochondrial DNA (mtDNA). The same mutation is seen in 80 percent of patients with MELAS (Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes). MIDD and MELAS have overlapping features suggesting a continuum of expression for the A3243G mutation. Clinical Case: A 41-year-old male was referred for genetic testing and counseling by his ophthalmologist following detection of bilateral punched-out retinal pigment epithelium (RPE) lesions on routine exam. His medical history was significant for type 1 diabetes mellitus (T1DM) diagnosed at the age of 21 and bilateral sensorineural hearing loss diagnosed at the age of 38. The referral was triggered by patient reported family history of MELAS in two of his brothers who were both diagnosed at the age of 10 and died at the ages of 20 and 27. Whether the patient was previously tested during early childhood remains unclear. His medical history was negative for stroke-like episodes or seizures. Neurologic evaluation revealed mild fluent aphasia with paraphasic errors and some comprehension difficulties. MRI of the brain without contrast showed no focus of restricted diffusion. Mitochondrial DNA sequence analysis was performed. A pathogenic variant (m.3243 A>G) was detected in the MT-TL1 gene at approximately 25% heteroplasmy. The patient was advised to avoid metformin given increased risk for lactic acidosis. He was also instructed against use of statins. At the age of 45, the patient presented to the emergency department (ED) with a complaint of headache, vertigo and incoordination. Physical examination revealed left homonymous hemianopsia, right horizontal nystagmus and bilateral upper extremity dysmetria. MRI of the brain without contrast showed a large area of predominantly cortical restricted diffusion involving the right temporal and occipital region with associated T2/FLAIR hyper-intensity. Cross over between the PCA and MCA territories was suggestive of a stroke-like episode related to MELAS. The patient received a bolus of IV arginine at 0.5 g/kg followed by an IV infusion of 0.5 g/kg/day for 3 days. He was later transitioned to oral arginine 5g three times daily and was discharged to a rehab facility. Clinical Lesson: This case demonstrates the evolution of MIDD to MELAS, supporting the concept that both syndromes represent a spectrum of the same disease. A few case reports describe the progression of MIDD to MELAS. Why some patients develop MELAS and others develop MIDD is unclear but may be related to heteroplasmy. Early identification of MIDD and MELAS is crucial given associated comorbidities and unique management issues.

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Hypoglycemia with lactic acidosis caused by a new MRPS2 gene mutation in a Chinese girl: a case report

BMC Endocrine Disorders ◽

10.1186/s12902-021-00924-1 ◽

2022 ◽

Vol 22 (1) ◽

Author(s):

ChangZhi Liu ◽

WeiRan Zhou ◽

QuanE Liu ◽

ZaiXin Peng

Keyword(s):

Hearing Loss ◽

Lactic Acidosis ◽

Sensorineural Hearing Loss ◽

Gene Mutation ◽

Clinical Manifestations ◽

Severe Hypoglycemia ◽

Sensorineural Hearing ◽

Chinese Girl ◽

Recurrent Vomiting ◽

Mitochondrial Defects

Abstract Background Mitochondrial ribosomal protein S2 (MRPS2) gene mutation, which is related to severe hypoglycemia and lactic acidosis, is rarely reported globally. Case presentation We report a case of a new MRPS2 gene mutation in a Chinese girl who presented with hypoglycemia and lactic acidosis. A homozygous C.412C > G variant that could cause complex oxidative phosphorylation deficiency and had not been reported before was identified. The clinical manifestations included recurrent vomiting, hypoglycemia, lactic acidosis, sensorineural hearing loss, and gall bladder calculi. Hypoglycemia and lactic acidosis improved after the administration of sugary liquid and supportive treatments. Conclusions Recurrent hypoglycemia with lactic acidosis and sensorineural hearing loss should lead to suspicion of mitochondrial defects and the early refinement of genetic tests.

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