The following mutations in MSH2 and MLH1 were described in their investigated Tunisian LS families; MSH2 (p.Gln402X, p.Pro472ThrfsX4, p.Arg243Gln, p.Ser281X and p.Gly713ArgfsX4) and MLH1 (p.Ala111Asp, p.Gln197ArgfsX8, p.His718Tyr, p.Lys392SerfsX9, p.Arg226X and p.Glu153PhefsX8) [20]. This evidence concerns the gene MLH1 and Leigh syndrome.