Behbehani et al. (2014) described a multigenerational Arab family with 14 members affected with LHON.  Molecular analysis, including sequence analysis of all four mitochondrial genes and full mtDNA sequencing, was carried out on 13 of these patients belonging to three kindreds.  All maternally related descendants were found to carry two variants in the ND4L gene; T10609C and T10663C.  These variants were predicted to cause a p.Ile47Thr and p.Val65Ala change in the protein, respectively.  The first of these variants was not found in any of 144 ethnically matched control population, while the latter was detected in two of these controls, with a frequency of 0.01%.  Haplogroup analysis of the mtDNA revealed all subjects, except two, to belong to haplogroup L3’4 with 100% clustering.

Abu-Amero and Bosley (2006) studied the molecular and biological characteristics of mitochondria in patients with Leber hereditary optic neuropathy (LHON)-like optic neuropathies.  Thirty five patients (21 males and 14 females) and 159 matched controls from Saudi Arabia were included in this study.  Forty one non-synonymous mtDNA sequence variants were identified in LHON patients; 14 were pathogenic.  Of these variants, 21 were in complex I, seven in complex III, five in complex IV, six in complex V, one in tRNA glutamine, and one in 12S rRNA.  Similar to previous reports on mutation association with LHON, these mtDNA changes were transitions.  Three pathogenic variants were found within the MT-ND4L gene; A10543G, T10591G, and T10663C.  The T10591G and T10663C mutations were present in one patient each.  The A10543G and T10591G nucleotide changes were heteroplasmic.