Clinical features of MS associated with Leber hereditary optic neuropathy mtDNA mutations

Harding disease refers to both multiple sclerosis and Leber Hereditary optic neuropathy (LHON) occurring together. This study looked at the association between these 2 conditions occurring by chance or if the two disorders are mechanistically linked in a cohort in the UK, looking at the prevalence of MS cases with LHON mitochondrial DNA (mtDNA) mutations.

The new cases were compared to published cases and a meta-analysis of studies screening patients with MS for LHON mtDNA mutations was also carried out to find evidence of a genetic association. They identified twelve new patients and 44 cases in the literature. Features typical for LHON included lack of eye pain and poor visual prognosis, which is unusual for optic neuritis associated with MS.

Overall the number of cases of LHON-MS was within the range predicted by the chance occurrence of MS and the mtDNA mutations known to cause LHON. However the resulting disorder has a distinct phenotype indicating mechanistic interaction. This study shows that while there was no association between MS and LHON in this data set, patients with LHON-MS had a more aggressive course than MS.

Authors: Pfeffer G, Burke A

Source: Neurology. 2013 Nov 6. [Epub ahead of print]

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