Webster's New World Medical Dictionary

mitochondrial
Referring to mitochondria.
mitochondrial disease
A mutation in the mito-
chondrial chromosome that is responsible for a dis-
ease. Known mitochondrial diseases include the eye
disease Leber hereditary optic atrophy; myoclonus
epilepsy with ragged red fibers (MERRF); and mito-
chondrial encephalopathy, lactic acidosis, and
stroke-like episodes syndrome (MELAS syndrome).
mitochondrial DNA
The DNA of the mitochon-
dria. Abbreviated mtDNA. There are 2 to 10 copies
of the mtDNA genome in each mitochondrion. The
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mitochondrial DNA
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mtDNA molecule is double-stranded and circular. It
is very small compared to the chromosomes in the
nucleus, and so it contains only a limited number of
genes. It is specialized in the information it carries,
and it encodes a number of the subunits in the mito-
chondrial respiratory-chain complex that the cell
needs in order to respire. It also contains genes for
some ribosomal RNAs and transfer RNAs. Mutations
in mtDNA can cause disease. These mutations often
impair the function of oxidative-phosphorylation
enzymes in the respiratory chain. This is especially
manifest in tissues with a high energy expenditure,
such as those of the brain and muscle. All mtDNA
comes from the oocyte at fertilization. Therefore,
inherited mtDNA mutations are transmitted from the
mother to both male and female offspring. 
mitochondrial encephalopathy, lactic
acidosis, and stroke-like episodes
See
MELAS syndrome.
mitochondrial encephalopathy, MELAS
See
MELAS syndrome.