A database study from two children's hospitals searched through brain magnetic imaging studies for likely MELAS patients. 124 studies from 14 MELAS patients (average age 16 years) were found. These revealed that gyral necrosis (the black toenail sign) is a common imaging feature which correlates with the disease duration.
MELAS is a genetic disorder (maternal inheritance - mtDNA) that results from mutation in one of several genes found in the DNA of mitochondria of the maternal ovum (sperm cells do not contribute to mitochondria in the developing embryo). Signs and symptoms (particularly involving the central nervous system and muscles) often appear in childhood after a normal period of growth and include muscle weakness and pain, recurrent headaches, loss of appetite vomiting and seizures. Many have single or multiple stroke-like episodes which damage the brain. Most have lactic acidosis.