cytoplasmic organelles that produce the energy source ATP for most chemical
reactions in the body, contain their own distinct genome; mutations in mitochondrial
genes are responsible for several recognized syndromes and are always maternally
inherited since ova contain mitochondria, whereas sperm do not
Definition from: GeneReviews
from the University of Washington and the National Center for Biotechnology Information
Related discussion in the Handbook
See also Understanding Medical Terminology.