A novel potassium channel gene, KCNQ2, is mutated in an inherited epilepsy of newborns.

Idiopathic generalized epilepsies account for about 40% of epilepsy up to age 40 and commonly have a genetic basis. One type is benign familial neonatal convulsions (BFNC), a dominantly inherited disorder of newborns. We have identified a sub-microscopic deletion of chromosome 20q13.3 that co-segregates with seizures in a BFNC family. Characterization of cDNAs spanning the deleted region identified one encoding a novel voltage-gated potassium channel, KCNQ2, which belongs to a new KQT-like class of potassium channels. Five other BFNC probands were shown to have KCNQ2 mutations, including two transmembrane missense mutations, two frameshifts and one splice-site mutation. This finding in BFNC provides additional evidence that defects in potassium channels are involved in the mammalian epilepsy phenotype.

Syncope in childhood.

The records of 108 children, ages 2 to 19 years (mean age 11.3 years), who were referred to the pediatric neurology and pediatric cardiology clinics for syncope, were reviewed. Sixty-six cases were identified retrospectively, and 42 prospectively. Syncope was defined as transient and complete loss of consciousness with no etiology determined at the time of presentation. The mean follow-up was 2.0 years. In 27 cases (25%), an etiology for syncope was found, including migraines in 12 cases (11%), seizures in 9 cases (8%), and cardiac arrhythmias in 6 cases (6%). All other cases were classified as vasovagal (neurocardiogenic). The past medical history, family history, clinical features of each syncopal episode, and diagnostic tests of each subject were correlated to final diagnosis. No clinical or historical features reliably distinguished children with vasovagal syncope from those with other etiologies. Children referred for the evaluation of syncope have a significant incidence of serious but treatable disorders, which should be actively sought.