The L158P substitution in the mitochondrially encoded ND4 subunit, observed in one patient with chronic progressive external ophthalmoplegia (Pulkes, Liolitsa, Nelson, & Hanna, 2003), was shown to affect complex I activity but not assembly when reconstructed in Chlamydomonas (Larosa, Coosemans, Motte, Bonnefoy, & Remacle, 2012). This evidence concerns the gene MT-ND4 and External ophthalmoplegia.