How common is KCNT2-related disorder?
Only three families are currently known around the world with a KCNT2-related condition, and we are still learning more about this condition.
What are the main symptoms associated with KCNT2-related disorder?
KCNT2-related disorder presents with seizures in the first weeks of life. Seizures can be of different types including stiffening of the body (tonic), jerking and changes in breathing or heart rate. The seizures are quite frequent (many per day) and often difficult to treat. Typically, the seizures are associated with abnormal brain wave patterns on EEG during this time. Children have some degree of developmental impairment involving one or more domains (motor, social, language, cognition). These features become present by early childhood.
How is KCNT2-related disorder inherited?
Individuals with KCNT2-related disorder typically come from families that have no family history of neurodevelopmental disorders or congenital conditions. The KCNT2 gene change occurs for the first time in the person with the condition. On occasion, one parent may have the KCNT2 mutation (gene change) in some of their egg or sperm cells but not be affected, as no other organ in their body has the mutation. This is called germline mosaicism and means that there is a very small chance that they may have another affected child. It would be important to discuss this possibility with your genetics team if you are planning another pregnancy.
What are the chances of an individual with KCNT2-related disorder having a child with KCNT2-related disorder?
While it is unlikely that an individual with KCNT2-related disorder who is severely affected will partner and have children, a carrier of a KCNT2 mutation that does go on to have children will have a 50% chance with each pregnancy of passing on the KCNT2 mutation. Children who inherit a KCNT2 mutation from their parent will experience a similar level of challenges as their parent; some may even experience difficulties and symptoms not seen in their parent. Genetic counselling is available through the local genetic service when planning a pregnancy and in early pregnancy.