Mitochondrial DNA depletion syndrome (MDS or MDDS): one of a number of diseases characterized by a decrease in the amount of mitochondrial DNA in affected body tissues. Mitochondria are structures within cells that are important for converting food into an energy form that cells can use, and they contain a small amount of DNA, although most of a cell's DNA resides within its nucleus. MDDS condition are genetic (inherited) and are passed to offspring in an autosomal recessive manner. The condition is usually fatal in infancy. Different forms of the condition affect the muscles (myopathic form), the liver (hepatopathic), or the or both the muscles and brain (encephalomyopathic). The condition gained much public attention in 2017 due to media reports of a boy named Charlie Gard born with the condition in the UK.
REFERENCE: National Institutes of Health; National Institute of Neurological Disorders and Stroke. "Mitochondrial Myopathy Information Page."