Classification of familial neonatal convulsions

Myokymia and neonatal epilepsy caused by a mutation in the voltage sensor of the KCNQ2 K + channel

“…Among these, BFNC are characterized by familial occurrence, normal psychomotor development, and a low rate of subsequent epilepsies (12-15%). Multifocal or generalized tonic-clonic convulsions typically start around day 3 after birth and disappear spontaneously after a few weeks or months (25,26). The major locus for BFNC is localized on chromosome 20q13.3 (27) and mutations of the K ϩ channel gene KCNQ2 have been identified as the underlying cause (12,13).…”

KCNQ2 encephalopathy: Emerging phenotype of a neonatal epileptic encephalopathy

“…Although BFNS is considered a benign condition, patients have a slightly increased risk of epilepsy later in life. 5,6 Mutations in KCNQ2 and KCNQ3, which encode the voltage-gated potassium channels Kv7.2 and Kv7.3 have been identified in 60% to 70% of families with BFNS. [7][8][9][10] Both genes are expressed in the central nervous system, where their gene products form heteromultimeric channels that mediate the M-current (IKM), a slowly activating, noninactivating potassium conductance that inhibits neuronal excitability.…”

A novel mutation in KCNQ2 gene causes benign familial neonatal convulsions in a Chinese family

“…The functional expression of some KCNQ2 mutations in Xenopus oocytes caused a 20-30% decrease in M-current compared with the wild-type. This slight loss of KCNQ2/KCNQ3 channel activity is sufficient to lead an hyperexcitability of certain neurons and thereby cause epilepsy [3,9]. Co-expression of the wild-type and the mutated protein led to a reduction of currents but not to a dominant negative effect.…”

“…The serum chemistry and neuroradiological examinations, interictal electroencephalogram (EEG), and psychomotor development are usually normal. However, 10% to 15% of patients have the risk of seizure recurrence later in life which are mostly described as generalized tonic or tonic -clonic seizures [1][2][3][4].…”