Our data confirm MT-ATP6/8 defect as prevalently associated with LS, as reported in previously described large cohort studies.22 The prevalence of NARP syndrome in our cohort was comparable with the results of a previous clinical-genetics study12 in a cohort of patients with MT-ATP6 variants that showed only 8% of patients with NARP. Here, MT-ATP6 is linked to NARP syndrome.