Using new genetic screening technology, a few research groups are finding that a surprisingly large number of children with autism — at least five percent — have an underlying problem with their mitochondria, the energy factories of the cell.If confirmed by larger studies, these preliminary results point to intriguing pathways, such as those involved in calcium-ion signaling, that go awry in the subgroup of children, the researchers say.It's unclear, however, whether mitochondrial defects are the primary causes of the disorder."This contributes to this general idea that you need multiple hits in order to get autism," notes Ricardo Dolmetsch, assistant professor of neurobiology at Stanford University School of Medicine, who was not involved in the new studies.For example, Dolmetsch notes, one of the hits may be a defect in a mitochondrial protein that, coupled with defects in genes that control electrical excitability, or in genes that control calcium channels, leads to autism.Read more at...SFARI, December 2009.