OPA1 and autosomal dominant optic atrophy: In order to gain insight into the pathogenesis of ADOA and the factors influencing penetrance, we characterized three independent OPA1 pathogenic mutations from three different families, examined their effects on mitochondrial morphology and cellular function in transfected HeLa and RGC5 cells, and further investigated the relationship between the OPA1 mutations and disease penetrance and severity.