Five KCNB1 mutants (L211P, R312HG379R, G381R, and F416L) linked to severe infancy or early-onset epileptic encephalopathy exhibited markedly defective conduction.
Despite the lack of prenatally described cases, we hypothesized that maldevelopment of lateral brain ventriculomegaly could be very early sonographic sign of disturbed ADNP expression causing Helsmoortel-Van der Aa syndrome, but in some extent also of KCNB1 related early-onset epileptic encephalopathy.
Recently, de novo heterozygous missense KCNB1 mutations have been identified in three patients with epileptic encephalopathy and a patient with neurodevelopmental disorder.