Neurological and non-neurological complications in adult-onset “Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis and Stroke-like episodes” syndrome: a diagnostic challenge for internal medicine. A narrative review

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episode (MELAS) syndrome is a rare genetic mitochondrial disease. Children are the most affected, but this syndrome can manifest at any age. The mA3243G is the most common mutation related to MELAS syndrome. Neurological complications are more frequently discussed in literature. However, it is imperative to address and discuss the non-neurological manifestations so that clinicians do not inadvertently overlook this disease. These are more common in adult patients and may appear before neurological symptoms. We conducted a narrative review of articles published between 2012 and 2024, with particular focus on on non-neurological disorders of MELAS syndrome. We found 657 papers related to MELAS syndrome. Only 31 papers discussed non-neurological complications. We divided those into cardiovascular, endocrinological, digestive, renal, and nutritional symptoms. The most prevalent disorders include hypertrophic cardiomyopathy, Wolff-Parkinson-White syndrome, chronic renal disease, intestinal pseudo-obstruction syndrome and malnutrition. The authors of this narrative review seek to shine light on non-neurological manifestations of MELAS syndrome. These are rarely described in the medical literature, despite their potentially significant clinical implications, especially in adult patients. Understanding the neurological and non-neurological complications associated with MELAS syndrome is essential for achieving a timely and definitive diagnosis.