Novel mutation in potassium channel related gene KCTD7 and progressive myoclonic epilepsy.

Progressive myoclonic epilepsy (PME) is a heterogeneous group of epilepsies characterized by myoclonus, seizures and progressive neurological symptoms. The index patient was a 6-year old boy showing early-onset therapy resistant PME and severe developmental delay. Genome-wide linkage analysis identified several candidate regions. The potassium channel tetramerization domain containing 7 gene (KCTD7) in the 7q11.21 linkage region emerged as a suitable candidate. Sequence analysis revealed a novel homozygous missense mutation (p.R94W) in a highly conserved segment of exon 2. This is the second family with PME caused by KCTD7 mutations, hence KCTD7 mutations might be a recurrent cause of PME.