Rare primary mitochondrial DNA mutations and probable synergistic variants in leber's hereditary optic neuropathy

Alessandro Achilli, Luisa Iommarini, Anna Olivieri, Maria Pala, Baharak Hooshiar Kashani, Pascal Reynier, Chiara La Morgia, Maria Lucia Valentino, Rocco Liguori, Fabio Pizza, Piero Barboni, Federico Sadun, Anna Maria de Negri, Massimo Zeviani, Helene Dollfus, Antoine Moulignier, Ghislaine Ducos, Christophe Orssaud, Dominique Bonneau, Vincent ProcaccioBeate Leo-Kottler, Sascha Fauser, Bernd Wissinger, Patrizia Amati-Bonneau, Antonio Torroni, Valerio Carelli

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Abstract

Background: Leber's hereditary optic neuropathy (LHON) is a maternally inherited blinding disorder, which in over 90% of cases is due to one of three primary mitochondrial DNA (mtDNA) point mutations (m.11778G>A, m.3460G>A and m.14484T>C, respectively in MT-ND4, MT-ND1 and MT-ND6 genes). However, the spectrum of mtDNA mutations causing the remaining 10% of cases is only partially and often poorly defined. Methodology/Principal Findings: In order to improve such a list of pathological variants, we completely sequenced the mitochondrial genomes of suspected LHON patients from Italy, France and Germany, lacking the three primary common mutations. Phylogenetic and conservation analyses were performed. Sixteen mitochondrial genomes were found to harbor at least one of the following nine rare LHON pathogenic mutations in genes MT-ND1 (m.3700G>A/p.A132T, m.3733G>A-C/p.E143K-Q, m.4171C>A/p.L289M), MT-ND4L (m.10663T>C/p.V65A) and MT-ND6 (m.14459G>A/p.A72V, m.14495A>G/p.M64I, m.14482C>A/p.L60S, and m.14568C>T/p.G36S). Phylogenetic analyses revealed that these substitutions were due to independent events on different haplogroups, whereas interspecies comparisons showed that they affected conserved amino acid residues or domains in the ND subunit genes of complex I. Conclusions/Significance: Our findings indicate that these nine substitutions are all primary LHON mutations. Therefore, despite their relative low frequency, they should be routinely tested for in all LHON patients lacking the three common mutations. Moreover, our sequence analysis confirms the major role of haplogroups J1c and J2b (over 35% in our probands versus 6% in the general population of Western Europe) and other putative synergistic mtDNA variants in LHON expression.

Original languageEnglish
Article numbere42242
JournalPLoS One
Volume7
Issue number8
DOIs
Publication statusPublished - 3 Aug 2012
Externally publishedYes

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Achilli, A., Iommarini, L., Olivieri, A., Pala, M., Hooshiar Kashani, B., Reynier, P., ... Carelli, V. (2012). Rare primary mitochondrial DNA mutations and probable synergistic variants in leber's hereditary optic neuropathy. PLoS One, 7(8), [e42242]. https://doi.org/10.1371/journal.pone.0042242