Recombination occurs in human mitochondrial DNA, says a team from the Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, in a “proof of concept” paper in Science this week that they say overturns current dogma of maternal inheritance and non-recombination.

Investigating the basis for a mitchondrial myopathy in a patient described in 2002, members of Kraytsberg's group had discovered that his muscle contained about 90% paternal mtDNA carrying a detrimental mutation responsible for the disease, Khrapko told The Scientist by email.

Using a restriction enzyme recognizing only paternal sequence, and single-molecule polymerase chain reaction (PCR) to amplify it, 33 out of 450 PCR clones from the subject's muscle tissue were found to contain both maternal and paternal sequence. Several recombinants contained more than one breakpoint—segments that join polymorphisms of different (paternal/maternal) descent—and three breakpoint hotspots were described as “highly significant.”

“The relevance of our results to evolution studies...

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