In such case, patients might possibly get a false positive classification as mitochondrial (group 1) based on biochemical criteria Still, concerning SLC19A3, either being primary or secondary, this gene should be tested in patients with Leigh syndrome, and should be in all MD panels, because it is a treatable condition, even though, having a secondary effect, it may not have been included in the MitoCarta database. The gene discussed is SLC19A3; the disease is Leigh syndrome.