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Progressive myoclonic epilepsy as an adult-onset manifestation of Leigh syndrome due to m.14487T>C.

Authors: Dermaut, B  Seneca, S  Dom, L  Smets, K  Ceulemans, L  Smet, J  De Paepe, B  Tousseyn, S  Weckhuysen, S  Gewillig, M  Pals, P  Parizel, P  De Bleecker, JL  Boon, P  De Meirleir, L  De Jonghe, P  Van Coster, R  Van Paesschen, W  Santens, P 
Citation: Dermaut B, etal., J Neurol Neurosurg Psychiatry. 2010 Jan;81(1):90-3.
Pubmed: (View Article at PubMed) PMID:20019223
DOI: Full-text: DOI:10.1136/jnnp.2008.157354

BACKGROUND: m.14487T>C, a missense mutation (p.M63V) affecting the ND6 subunit of complex I of the mitochondrial respiratory chain, has been reported in isolated childhood cases with Leigh syndrome (LS) and progressive dystonia. Adult-onset phenotypes have not been reported. OBJECTIVES: To determine the clinical-neurological spectrum and associated mutation loads in an extended m.14487T>C family. METHODS: A genotype-phenotype correlation study of a Belgian five-generation family with 12 affected family members segregating m.14487T>C was carried out. Clinical and mutation load data were available for nine family members. Biochemical analysis of the respiratory chain was performed in three muscle biopsies. RESULTS: Heteroplasmic m.14487T>C levels (36-52% in leucocytes, 97-99% in muscle) were found in patients with progressive myoclonic epilepsy (PME) and dystonia or progressive hypokinetic-rigid syndrome. Patients with infantile LS were homoplasmic (99-100% in leucocytes, 100% in muscle). We found lower mutation loads (between 8 and 35% in blood) in adult patients with clinical features including migraine with aura, Leber hereditary optic neuropathy, sensorineural hearing loss and diabetes mellitus type 2. Despite homoplasmic mutation loads, complex I catalytic activity was only moderately decreased in muscle tissue. INTERPRETATION: m.14487T>C resulted in a broad spectrum of phenotypes in our family. Depending on the mutation load, it caused severe encephalopathies ranging from infantile LS to adult-onset PME with dystonia. This is the first report of PME as an important neurological manifestation of an isolated mitochondrial complex I defect.

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CRRD Object Information
CRRD ID: 6482231
Created: 2012-04-19
Species: All species
Last Modified: 2012-04-19
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.