Nevertheless, it should be stressed that DOA is frequently associated to secondary symptoms, most often neurosensory deafness (Amati-Bonneau et al., 2005), but also external ophthalmoplegia, myopathy, peripheral neuropathy, ataxia, and spastic paraplegia for OPA1 patients (Yu-Wai-Man et al., 2010), and cataract, postural tremor, extrapyramidal signs, ataxia, areflexia, and neurosensory deafness for OPA3 patients (Reynier et al., 2004; Ayrignac et al., 2012; Grau et al., 2013). Here, OPA1 is linked to sensorineural hearing loss disorder.