Our results evidence that components of the N-module were the most significantly downregulated in mitochondria from the VN of Vglut2:Ndufs4cKO mice, indicating a critical role of this accessory subunit in the assembly and/or stability of the N-module component of CI, and confirming previous studies in LS patients harboring NDUFS4 mutations (Scacco et al., 2003) and Ndufs4-deficient mice (Calvaruso et al., 2012; Leong et al., 2012; Valsecchi et al., 2012). Here, NDUFS4 is linked to Leigh syndrome.