Clinical Characteristics

Most children with KCNN2 mutations are slower to develop physical, emotional, social and communication skills than expected (developmental delay). 90% of adolescents or adult patients have limitations in their intellectual functions including difficulties in learning and communicating (intellectual disability) and may also have impaired social skills or restricted interests (autism). More than half of affected subject will present abnormal movement or problems in coordination and balance during their life. These abnormal movements differ from one person to the other and include cerebellar ataxia, tremors, rigidity and/or slowness, motor tics (head jerking, eye blinking), or other neurological symptoms. A few patients will have epilepsy. Older subjects may present psychotic episodes or psychiatric features.

Clinical variability
The severity of KCNN2-related disorders is variable from one patient to the other: some patients will be severely impaired while other will have a milder handicap.