Before genetic testing results, involvement of mitochondrial genes such as the SLC25A46 gene or the OPA3 gene has been evoked because of their known association with severe form of sensory motor axonal neuropathy, optic atrophy and gastrointestinal dysmobility (Abrams et al., 2015; Horga et al., 2019). The gene discussed is OPA3; the disease is optic atrophy.