The complete sequencing of mtDNA revealed the presence of two homoplasmic variants: the m.﻿11778G > A change in MTND4, known to be associated with Leber’s hereditary optic neuropathy (LHON), and the m.﻿﻿3337G > C change in MTND1. The latter is expected to cause the p.﻿Val11Leu substitution, affecting a poorly conserved amino acid residue (with leucine present in chicken). The gene discussed is MT-ND4; the disease is Leber hereditary optic neuropathy.