The c.1A>C SDHA variant was identified in trans with a c.1571C>T p.(Ala524Val) SDHA missense variant (discussed in missense SDHA variant section) in a clinically-affected child who presented with Leigh syndrome (Case 6,Table 1); only marginal amounts of the c.1A>C-associated transcript were detectable, presumably utilising the in-frame methionine occurring at Met114, but would nevertheless be non-functional due to the absence of the N terminal residues of the protein which serve to target the apoprotein to the mitochondria [20]. This evidence concerns the gene SDHA and Leigh syndrome.