Digenic Leigh syndrome on the background of the m.11778G>A Leber hereditary optic neuropathy variant

• Published in: Brain (London, England : 1878) Vol. 147; no. 6; pp. 1967 - 1974
• Main Authors: Blickhäuser, Beryll, Stenton, Sarah L, Neuhofer, Christiane M, Floride, Elisa, Nesbitt, Victoria, Fratter, Carl, Koch, Johannes, Kauffmann, Birgit, Catarino, Claudia, Schlieben, Lea Dewi, Kopajtich, Robert, Carelli, Valerio, Sadun, Alfredo A, McFarland, Robert, Fang, Fang, La Morgia, Chiara, Paquay, Stéphanie, Nassogne, Marie Cécile, Ghezzi, Daniele, Lamperti, Costanza, Wortmann, Saskia, Poulton, Jo, Klopstock, Thomas, Prokisch, Holger
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 03.06.2024
• Subjects: Adolescent; Adult; Child; Child, Preschool; DNA, Mitochondrial - genetics; Electron Transport Complex I - genetics; Exome Sequencing; Female; Humans; Leigh Disease - genetics; Male; Mutation; NADH Dehydrogenase - genetics; Optic Atrophy, Hereditary, Leber - genetics; Young Adult; Leigh syndrome spectrum (LSS); digenic inheritance; Leber hereditary optic neuropathy (LHON); mitochondrial complex I (CI)
• ISSN: 0006-8950; 1460-2156; 1460-2156
• DOI: 10.1093/brain/awae057

Abstract Leigh syndrome spectrum (LSS) is a primary mitochondrial disorder defined neuropathologically by a subacute necrotizing encephalomyelopathy and characterized by bilateral basal ganglia and/or brainstem lesions. LSS is associated with variants in several mitochondrial DNA genes and more than 100 nuclear genes, most often related to mitochondrial complex I (CI) dysfunction. Rarely, LSS has been reported in association with primary Leber hereditary optic neuropathy (LHON) variants of the mitochondrial DNA, coding for CI subunits (m.3460G>A in MT-ND1, m.11778G>A in MT-ND4 and m.14484T>C in MT-ND6). The underlying mechanism by which these variants manifest as LSS, a severe neurodegenerative disease, as opposed to the LHON phenotype of isolated optic neuropathy, remains an open question. Here, we analyse the exome sequencing of six probands with LSS carrying primary LHON variants, and report digenic co-occurrence of the m.11778G > A variant with damaging heterozygous variants in nuclear disease genes encoding CI subunits as a plausible explanation. Our findings suggest a digenic mechanism of disease for m.11778G>A-associated LSS, consistent with recent reports of digenic disease in individuals manifesting with LSS due to biallelic variants in the recessive LHON-associated disease gene DNAJC30 in combination with heterozygous variants in CI subunits.Blickhäuser et al. examine why certain individuals carrying specific mitochondrial DNA variants primarily associated with optic neuropathy experience exceptionally severe Leigh syndrome spectrum disease. They conclude that the co-occurrence of these variants with a second variant in an interacting gene causes the more severe phenotype.