As other studies have reported [32,59], the clinical phenotype for SBG1-FB-MT-ATP6-T8993G was classic ‘LS’, while for SBG2-FB MT-ATP6-T8993G was ‘developmental delay, abnormal gait’; and for SBG3-FB-MT-ATP6-T9185C a mild myopathy and late disease onset. This evidence concerns the gene MT-ATP6 and Global developmental delay.