NDUFAF2 and Leber hereditary optic neuropathy: In the current study, we describe three patients (P1, P2, P4) from two separate families who presented with infantile onset nystagmus and evolving optic atrophy, and progressive neurodegeneration with profound brainstem disruption, due to a homozygous loss-of-function pathogenic variant in NDUFAF2. Another patient (P3), a sibling of two genetically confirmed patients (P2 and P4) with a rather similar phenotype, died abruptly before any genetic investigations could be performed.