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TitleMild Leber Hereditary Optic Neuropathy (LHON) in a Western European family due to the rare Chinese m.14502T>C mutation
PurposeLHON is a maternally inherited bilateral blinding disorder. Over 90% of cases is due to one of 3 primary mitochondrial DNA (mtDNA) point mutations: m.11778G>A, m.3460G>A and m.14484T>C. The remaining 10% of cases are associated with>40 point mutations with variable penetrance and incidence between different ethnic backgrounds.
MethodsThree sisters with a proven homoplasmic m.14502T>C mutation in the MT-ND6 gene underwent a detailed ophthalmic workup.
ResultsThe 24 year-old index patient was referred for acute visual loss to counting fingers in the right eye. Optic atrophy developed, confirmed on OCT. Functional testing showed severe color deficiency, an absolute central scotoma, and loss of P100 on PVEP. All testing of the left eye was unremarkable. The patient was in general good health but displayed marked use of alcohol and tobacco. An etiologic workup including brain imaging and biochemical tests for auto-immune, cardiovascular,inflammatory, infectious and toxic causes were all negative. Mt-DNA analysis did not reveal a common LHON point mutation but a rare Chinese m.14502T>C mutation.
A family workup showed bilateral temporal pallor of the optic disc without functional impact in a 30 year-old sister who smoked 20 cigarettes a day. A 27 year-old sister without tobacco use had a normal exam.
ConclusionThe rare Chinese m.14502T>C mutation in the MT-ND6 gene was linked to mild LHON in a Western European family. Penetrance in this family was likely to be triggered by alcohol and tobacco abuse. A full mtDNA sequence is warranted in case of high clinical suspicion of LHON lacking the 3 common mutations. Smoking cessation and reduction of alcohol use should be discussed to avoid further visual loss.
Conflict of interestNo
Authors 1
Last nameVANDEPUTTE
InitialsJ
DepartmentUZ Gent
CityGent
Authors 2
Last nameSENECA
InitialsS
DepartmentCtr Medical Genetics,VUB
CityBrussel
Authors 3
Last nameDE ZAEYTIJD
InitialsJ
DepartmentUZ Gent
CityGent
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