The m.3243A>G mitochondrial DNA mutation and related phenotypes. A matter of gender?
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The m.3243A>G “MELAS” (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) mutation is one of the most common point mutations of the mitochondrial DNA, but its phenotypic variability is incompletely understood. The aim of this study was to revise the phenotypic spectrum associated with the mitochondrial m.3243A>G mutation in 126 Italian carriers of the mutation, by a retrospective, database-based study (“Nation-wide Italian Collaborative Network of Mitochondrial Diseases”). Our results confirmed the high clinical heterogeneity of the m.3243A>G mutation. Hearing loss and diabetes were the most frequent clinical features, followed by stroke-like episodes. “MIDD” (maternally-inherited diabetes and deafness) and “PEO” (progressive external ophthalmoplegia) are nosographic terms without any real prognostic value, because these patients may be even more prone to the development of multisystem complications such as stroke-like episodes and heart involvement. The “MELAS” acronym is convincing and useful to denote patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Of note, we observed for the first time that male gender could represent a risk factor for the development of stroke-like episodes in Italian m.3243A>G carriers. Gender effect is not a new concept in mitochondrial medicine, but it has never been observed in MELAS. A better elucidation of the complex network linking mitochondrial dysfunction, apoptosis, estrogen effects and stroke-like episodes may hold therapeutic promises.
KeywordsA3243G MELAS MIDD Mitochondrial DNA PEO Stroke-like episodes
This work was supported by Telethon (grant number GUP09004). The authors are grateful to the Italian patient association “Mitocon” for the informatic support. The work of the “Besta” group of Milan was supported by the Pierfranco and Luisa Mariani Foundation Italy, Ricerca 2000; Fondazione Giuseppe Tomasello ONLUS and Fondazione Telethon-Italy grants GGP07019 and GPP10005. The work of the University of Milan group was supported by Associazione Amici del Centro Dino Ferrari, by the Telethon project GTB07001ER, and by a Telethon grant “Network of Genetic Biobanks” no GTB07001.
Conflicts of interest
The authors declare no conflicts of interest.
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