NDUFS2 and Leber hereditary optic neuropathy: Secondly, both patients complained of a rather sudden painless loss of visual acuity, similar to those observed in maternally inherited LHON, although without optic disk elevation or edema, which is distinct from what is generally observed for other autosomal optic neuropathies, except for a recent report presenting a LHON-like patient with bi-allelic NDUFS2 mutations [22].