[Two new cases of Leigh syndrome caused by mutation m.13513G> A in the MTND5 gene]

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.

MELAS with multiple stroke-like episodes due to the variant m.13513G>A in MT-ND5

Mitochondrial encephalopathy, lactic acidosis, and stroke‐like episodes (MELAS) is characterized by metabolic stroke, seizures, cognitive decline, lactic acidosis, ragged‐red fibers, headache, and vomiting, and in 80% of cases due to the mtDNA variant m.3243A>G. We report the case of a MELAS patient carrying a variant in subunit‐5 of the respiratory chain (MT‐ND5), rarely reported in MELAS. The patient is a 33‐year‐old male, who experienced a series of stroke‐like episodes (StLEs) since age 23 years, which manifested clinically as seizures transient sensory disturbances, weakness, and visual or cognitive impairment. Over 9 years, these StLEs were misinterpreted as ischemic strokes, respectively, as cerebral vasculitis. He presented with mild, recurrent elevations of the creatine kinase. Initially, anti‐seizure drugs and steroids appeared to be beneficial. Despite good recovery of each single StLE, the patient experienced a progressive decline of cognitive functions and activities of daily living. Cerebral imaging showed corresponding stroke‐like lesions in changing locations. At age 32y, genetic work‐up revealed the variant m.13513G>A in MT‐ND5. The patient profited significantly from a cocktail with anti‐oxidants/cofactors. This case shows that the variant m.13513G>A in MT‐ND5 can manifest as MELAS that StLEs recover spontaneously and that the course of MELAS is slowly progressive.