NDUFB7 is an accessory subunit of mitochondrial Complex I (NADH:ubiquinone oxidoreductase) that functions in the electron transfer chain, facilitating electron transfer from NADH to ubiquinone 1. The protein is N-myristoylated and contains a CHCH domain, both of which are essential for its mitochondrial localization 2. NDUFB7 is critical for Complex I assembly and supercomplex formation 1. Pathogenic NDUFB7 mutations cause mitochondrial Complex I deficiency (nuclear type 39), characterized by severe multi-organ manifestations. Patients with biallelic NDUFB7 mutations present with lactic acidosis, brain abnormalities (pons abnormality, neuronal defects, encephalopathy), hypertrophic cardiomyopathy, growth restriction, and cardiorespiratory defects 13. Zebrafish Ndufb7 knockdown recapitulates these phenotypes, including elevated lactic acid and reduced oxygen consumption 1. Additionally, NDUFB7 upregulation in diabetic retinopathy promotes pathogenic retinal vascular endothelial cell proliferation and reduces apoptosis, regulated by miR-2861 4. NDUFB7 downregulation is also associated with COPD pathogenesis 5. Therapeutically, coenzyme Q10, vitamin B complex, and mitochondrial-targeted antioxidants (MitoQ) ameliorate disease manifestations 1, suggesting potential treatment strategies for Complex I deficiency.