Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-Like Episodes/Leigh Overlap Syndrome Due to Variant m.13513G>A in MT-ND5.

Mitochondrial disorders are caused due to variants in genes located on the mitochondrial DNA or the nuclear DNA. Here, we report a case with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)/Leigh overlap syndrome due to variant m.13513G>A in ND5. A 60-month-old female with a congenital, complex, multisystem phenotype was diagnosed with MELAS/Leigh overlap syndrome due to variant m.13513G>A in ND5. Brainstem involvement resulted in dysphagia, dysarthria, and respiratory failure with recurrent episodes of aspiration, respiratory insufficiency, desaturations, lack of respiratory drive, hypercapnia, and pneumonia. Treatment was symptomatic and included non-invasive ventilation, antibiotics, implantation of a percutaneous endoscopic gastrostomy, anti-seizure drugs, anti-dystonia medication, a cocktail of vitamins and antioxidants, and analgesics. Despite these measures, the outcome was poor as the patient died at the age of 62 months after being discharged to home palliative care. In summary, the m.13513G>A variant can manifest as MELAS/Leigh overlap syndrome with Leigh syndrome dominating. Because of brainstem involvement leading to respiratory dysfunction, dysarthria, and dysphagia, the outcome is poor, despite symptomatic measures.