Peculiar combinations of individually non-pathogenic missense mitochondrial DNA variants cause low penetrance Leber’s hereditary optic neuropathy

Leonardo Caporali, Luisa Iommarini, Chiara La Morgia, Anna Olivieri, Alessandro Achilli, Alessandra Maresca, Maria Lucia Valentino, Mariantonietta Capristo, Francesca Tagliavini, Valentina Del Dotto, Claudia Zanna, Rocco Liguori, Piero Barboni, Michele Carbonelli, Veronica Cocetta, Monica Montopoli, Andrea Martinuzzi, Giovanna Cenacchi, Giuseppe De Michele, Francesco TestaAnna Nesti, Francesca Simonelli, Anna Maria Porcelli, Antonio Torroni, Valerio Carelli

Research output: Contribution to journalArticlepeer-review


We here report on the existence of Leber’s hereditary optic neuropathy (LHON) associated with peculiar combinations of individually non-pathogenic missense mitochondrial DNA (mtDNA) variants, affecting the MT-ND4, MT-ND4L and MT-ND6 subunit genes of Complex I. The pathogenic potential of these mtDNA haplotypes is supported by multiple evidences: first, the LHON phenotype is strictly inherited along the maternal line in one very large family; second, the combinations of mtDNA variants are unique to the two maternal lineages that are characterized by recurrence of LHON; third, the Complex I-dependent respiratory and oxidative phosphorylation defect is co-transferred from the proband’s fibroblasts into the cybrid cell model. Finally, all but one of these missense mtDNA variants cluster along the same predicted fourth E-channel deputed to proton translocation within the transmembrane domain of Complex I, involving the ND1, ND4L and ND6 subunits. Hence, the definition of the pathogenic role of a specific mtDNA mutation becomes blurrier than ever and only an accurate evaluation of mitogenome sequence variation data from the general population, combined with functional analyses using the cybrid cell model, may lead to final validation. Our study conclusively shows that even in the absence of a clearly established LHON primary mutation, unprecedented combinations of missense mtDNA variants, individually known as polymorphisms, may lead to reduced OXPHOS efficiency sufficient to trigger LHON. In this context, we introduce a new diagnostic perspective that implies the complete sequence analysis of mitogenomes in LHON as mandatory gold standard diagnostic approach.

Original languageEnglish
Article numbere1007210
JournalPLoS Genetics
Issue number2
Publication statusPublished - Feb 1 2018

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics
  • Genetics(clinical)
  • Cancer Research


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