Epileptic seizures and syndromes in twins: the importance of genetic factors.
ABSTRACT The role of genetic factors in the occurrence of epilepsy syndromes was studied in twins recruited from the population-based Danish Twin Registry. A total of 34,076 twins were screened for epilepsy. Cases were confirmed and classified by two neurologists according to the classification systems of the International League Against Epilepsy (ILAE). A total of 214 twin pairs with epileptic seizures and 190 pairs with epilepsy were ascertained. Significantly higher concordance rates were found for monozygotic (MZ) compared to dizygotic (DZ) twins for both epileptic seizures (0.56 for MZ and 0.21 for DZ pairs, P<0.001) and for epilepsy (0.49 for MZ and 0.16 for DZ pairs, P<0.001). Concordance rates were also higher for MZ twins compared to DZ twins for both generalized epilepsy (0.65 for MZ and 0.12 for DZ) and for localization-related epilepsy (0.30 for MZ and 0.10 for DZ). In twin pairs where both members had seizures, 83% of MZ and 65% of DZ pairs had the same major epilepsy syndrome. Genetic factors were found to account for 80% of the liability to both epileptic seizures and epilepsy. In conclusion, analysis of this neurologist-verified epilepsy twin data set has confirmed that genetic factors have a substantial impact on the etiology of epileptic seizures as well as on the occurrence of both generalized and partial epilepsies.
- Annals of Human Genetics 09/2007; 29(1):51 - 76. · 2.22 Impact Factor
Article: Classical twin studies and beyond.[show abstract] [hide abstract]
ABSTRACT: Twin studies have been a valuable source of information about the genetic basis of complex traits. To maximize the potential of twin studies, large, worldwide registers of data on twins and their relatives have been established. Here, we provide an overview of the current resources for twin research. These can be used to obtain insights into the genetic epidemiology of complex traits and diseases, to study the interaction of genotype with sex, age and lifestyle factors, and to study the causes of co-morbidity between traits and diseases. Because of their design, these registers offer unique opportunities for selected sampling for quantitative trait loci linkage and association studies.Nature Reviews Genetics 12/2002; 3(11):872-82. · 41.06 Impact Factor
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ABSTRACT: Before one starts the hunt for quantitative trait loci (QTLs) for a complex trait, it is necessary to show that the trait is genetically influenced. This evidence is most likely to come from the classical twin study--the demonstration that monozygotic twins are more similar for the trait than dizygotic twins. The strengths and weaknesses of twin studies are discussed, and it is suggested that, far from becoming irrelevant with advances in molecular biology, they can improve the efficiency of QTL detection and play an important role in unravelling developmental genetic mechanisms.Nature Genetics 01/1998; 17(4):387-92. · 35.21 Impact Factor