Individuals with KCNB1 encephalopathy have variable degrees of neurodevelopmental disorders associated with epilepsy.
About half of the patients also have behavioral disorders, including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).
In some individuals with KCNB1-related disorders, seizures can occur early in life and impact further the neurodevelopment giving a developmental and epileptic encephalopathy ( (KCNB1-DEE). In this group, seizures are frequent and resistant to anti seizure medications. In others, seizures may occur later in childhood and might be more responsive to therapies. Common seizure types may include:
• Generalized tonic-clonic seizures
• Infantile spasms
• Tonic seizures
• Clonic seizures
• Myoclonic seizures
• Atypical absence seizures
• Atonic seizures
Many individuals with KCNB1-related disorders may also have:
• Hypotonia
• Spasticity
• Movement disorders, particularly ataxia, dystonia or chorea
• Behavior disorders, including aggression, hyperactivity
• Autism spectrum disorder (ASD)
• Borderline long QT and/or autonomic nervous system abnormalities
Some patients might present ophtalmologic disorders (either strabismus or cortical visual impairment), gasto-intestinal issues, and sleep disorders.
KCNB1