A new pathophysiological mechanism to explain asymmetry in mitochondrial myopathies

Mitochondrial diseases are a heterogeneous group of disorders caused by alterations in mitochondrial DNAmacromolécule complexe, l’ADN est le support de l’hérédité (gènes). C’est le constituant des chromosomes. L’ADN est organisé en double hélice (deux brins complémentaires) et constitué de nucléotides de quatre types : adénine, guanine, cytosine et thymine. (missense mutations, sporadic large-scale deletions or mutations in nuclear maintenance genes). In these rare and complex diseases, symptoms can vary from person to person and between different tissues in a individual. More than 350 genes have been identified.

A team of French clinicians involving doctors from the Institute of Myology report the case of a 34 year old patient with highly asymmetric segmental and oculomotor muscle damage. Biochemical and genetic analyses of mitochondrial DNA were instrumental in explaining this exceptional presentation.

This case demonstrates that the highly asymmetric distribution of muscle wasting correlates with levels of heteroplasmy that can vary drastically for a given muscle type. The authors suggest that this is a new pathophysiological mechanism that may explain the asymmetry in hereditary myopathies.

Highly asymmetrical distribution of muscle wasting correlates to the heteroplasmy in a patient carrying a large-scale mitochondrial DNA deletion: a novel pathophysiological mechanism for explaining asymmetry in mitochondrial myopathies. Masingue M, Rucheton B, Bris C, Romero NB, Procaccio V, Eymard B. Neuromuscul Disord. 2022 Dec;32(11-12):923-930. doi: 10.1016/j.nmd.2022.10.006. Epub 2022 Oct 27. PMID: 36428163