Article title
Bao X, Downs J, Wong K, Williams S, Leonard H. Using a large international sample to investigate epilepsy in Rett syndrome. Developmental Medicine & Child Neurology. 2013;55(6):553-558. doi: 10.1111/dmcn.12093. Download snapshot, see article abstract.
Background
Seizures occur commonly in Rett syndrome. Studies have shown that the type of MECP2 mutation is likely to influence the development of epilepsy. Using a large sample size, we investigated the relationships between epilepsy and genotype, and the impact of medications used on seizure management.
What we did
We collected information from 685 girls with a pathogenic MECP2 mutation who were registered with the international database InterRett on the seizure characteristics and antiepileptic medications used. We then compared seizure frequency by age, and investigated the age or epilepsy onset, relationships with mutation type and the medications used.
What we found
Active epilepsy of at least monthly frequency occurred most commonly in those aged 12 to 17 years (54%). Half of the girls in the study had developed seizures by the age of 5 years, whilst those with large deletion and p.R133C had the earliest (3 years 5 months) and latest (>6 years) average onset of epilepsy respectively.
Comparing among genotypes, those with a large deletion and p.T158M had increased risk of developing active seizures. Girls with the p.R168X and p.255X mutations were at increased risk of drug resistant epilepsy, defined as having active seizures and taking two or more antiepileptic medications.
The five most commonly used medicines were valproate or depakote (used by 47%), carbamazepine or tegretol (used by 39%); lamotrigine or lamictal (used by 30%); levetiracetam or keppra (used by 24%) and topiramate or topamax (used by 19%).
For those with drug resistant epilepsy, levetiracetam, zonisamide, lamotrigine, clonazepam and oxcarbazepine were most likely to be used.
What it means
We confirmed that epilepsy occurs frequently in those aged 7 to 17 years and that genotype influences the age at onset and severity of epilepsy in Rett syndrome. We also showed the significance of the burden of epilepsy for those with Rett syndrome and their families, as one-third of those with epilepsy were still having seizures despite taking two or more antiepileptic medications.It will be important for future studies to look at in details the seizure characteristics (e.g. seizure type) and the medication used in a longitudinal manner.