NDUFAF8 is a mitochondrial assembly factor required for the biogenesis of NADH:ubiquinone oxidoreductase complex I, the first enzyme complex in the oxidative phosphorylation chain. It stabilizes NDUFAF5, another early-stage assembly factor, and is essential for proper complex I assembly and function. Pathogenic bi-allelic variants in NDUFAF8 cause mitochondrial complex I deficiency 1, presenting clinically as Leigh syndrome—a severe neurological disorder characterized by symmetrical basal ganglia, thalamic, and brainstem lesions, developmental delay, and loss of motor skills in affected children 1. Beyond Leigh syndrome, NDUFAF8 variants have been identified in patients with autosomal recessive Leber hereditary optic neuropathy (arLHON), where disease presents with insidious-onset vision loss rather than the multi-system neurological phenotype 2. Reported variants include deep-intronic splicing mutations that may be overlooked during standard diagnostic screening 1. Lentiviral transduction with wild-type NDUFAF8 restores complex I assembly and biochemical function in patient-derived fibroblasts, establishing proof-of-concept for potential gene therapeutic approaches 1. Comprehensive genomic screening of both mitochondrial and nuclear genomes is critical for reliable molecular diagnosis, as genetic heterogeneity complicates phenotypic prediction.