Mutation information:
NumberExon/IntronNucleotide change Protein changeLocation Mutation typeConsequencesPhenotype InheritanceReference
67615c.2593C>Gp.Arg865GlyDIIS4MissenseP/﹢→N (125); G-LOFSMEINAVolkers L.2011

Functional information:
NumberNucleotide changeProtein changeLocationPhenotypeFunctional defect type Details of the major biophysical abnormalities.Reference
15c.2593C>Gp.Arg865Gly(R865G)DIIS4SMEIG-LOFA large increase in persistent current, and a hyperpolarized shift in the voltage dependence of activation in combination with the unaltered voltage dependence of inactivation; slower recovery from inactivation.Volkers L.2011

[c.2593C>G] Clinical description

The novel R865G mutation was detected in a boy who had right-sided hemiconvulsions with postictal hemiparesis since the age of nine months. He also experienced myoclonic jerks and complex partial seizures. His EEGs showed a near normal background pattern with isolated sharps and sharp waves in both hemispheres. He was diagnosed with DS. Magnetic resonance brain imaging was normal. At the age of 60 months, he was deemed to have a severe developmental delay with a developmental age of 29 months. After addition of levetiracetam to valproate and lamotrigine at the age of 6.5 years he is seizure free till to date.His family history was negative for febrile convulsions and epilepsy. His parents are consanguineous. DNA analysis of the parents was not available(Volkers L,et al. Eur J Neurosci. 2011 Oct;34(8): 1268-75. [21864321]).