Epilepsies in twins: Genetics of the major epilepsy syndromes

Authors

  • Dr Samuel F. Berkovic MD, FRACP,

    Corresponding author
    1. Department of Medicine (Neurology), University of Melbourne, Austin and Repatriation Medical Centre, Heidelberg (Melbourne)
    • Department of Neurology, Austin and Repatriation Medical Centre, Heidelberg (Melbourne), Victoria, 3084, Australia
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  • R. Anne Howell MSc,

    1. Department of Medicine (Neurology), University of Melbourne, Austin and Repatriation Medical Centre, Heidelberg (Melbourne)
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  • David A. Hay PhD,

    1. Department of Psychology, La Trobe University, Melbourne, Australia
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  • John L. Hopper PhD

    1. Department of Public Health and Community Medicine, Australin NHMRC Twin Registry, University of Melbourne, Melbourne, Australia
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Abstract

We studied twins to examine the genetics of epilepsy syndromes. We ascertained 358 twin pairs in whom one or both reported seizures. After evaluation, 253 of 358 (71%) had seizure disorders and 105 pairs were false positives. Among the monozygous (MZ) pairs, more were concordant for seizures (48 of 108; casewise concordance = 0.62 ± 0.05) than among the dizygous (DZ) pairs (14 of 145; casewise concordance = 0.18 ± 0.04). In 94% of concordant MZ pairs, and 71% of concordant DZ pairs, both twins had the same major epilepsy syndrome. When analyzed according to major epilepsy syndrome, the casewise concordances for generalized (MZ = 0.82; DZ = 0.26), both idiopathic (MZ = 0.76; DZ = 0.33) and symptomatic (MZ = 0.83; DZ = 0), were greater than those for partial epilepsies (MZ = 0.36; DZ = 0.05), with intermediate values seen for febrile seizures (MZ = 0.58; DZ = 0.14) an dunclassified epilepsies (MZ = 0.53; DZ = 0.18). We conclude that genetic factors are particularly important in the generalized epilepsies but also play a role in the partial epilepsies. The high frequency of concordant MZ pairs with the same major syndrome strongly suggets there are syndrome-specific genetic determinants rather than a broad genetic predisposition to seizures.

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