the online version of this article ( doi:10.1007/s11011 - 014 - 9645-x ) contains supplementary material , which is available to authorized users .
video segment 2 : the patient at the age of 22 , he has been on levetiracetam for 2  months .
all authors declare no conflict of interest and the presented case study has been performed in accordance with the ethical standards laid down in the 1964 declaration of helsinki and its later amendments .
furthermore all authors declare that the submitted work has not been published before ( neither in english nor in any other language ) and that the work is not under consideration for publication elsewhere .
 mutations in nadh dehydrogenase ( nd ) subunits of complex i lead to mitochondrial encephalomyopathies associated with various phenotypes . 
 this report aims to present the patient s clinical symptomatology in the context of a very rare 13042g > a de novo mutation and with an emphasis on changing phenotypic expression and pronounced , long - standing response to levetiracetam.electronic supplementary materialthe online version of this article ( doi:10.1007/s11011 - 014 - 9645-x ) contains supplementary material , which is available to authorized users . 
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