Mitochondria are organelles responsible for critical cellular functions. Mitochondria have their own DNA (mtDNA) and are inherited maternally, that is, transmitted only through the female line. mtDNA sequence is used to verify maternal lineages. In horse cloning, mtDNA analysis in conjunction with nuclear DNA testing is used to validate that an individual is a clone.
The sample requirement is a sample from the subject animal along with a sample from at least one of the subject's maternal relatives.