MT-ND5 and Kearns-Sayre syndrome: In these studies, RNA mitochondrial import induced the heteroplasmy shift in several cellular models: a) human cybrid cells and patient’s fibroblasts bearing a heteroplasmic point mutation in ND5 gene [19] and b) human cybrid cell line bearing 60% of mtDNA affected by a large deletion (nucleotides 8363–15438) underlying a case of frequent mitochondrial pathology, the Kearns Sayre Syndrome (KSS) [12].