Families

What is a KCNMA1-linked channelopathy?
The KCNMA1 gene encodes for a human potassium channel, a type of protein that allows brain cells to conduct electrical signals.  Variants in the gene can result in ‘KCNMA1-linked channelopathy,’ a disorder thought to involve abnormal electrical signaling in the brain and possibly other tissues. The disorder is characterized by overlapping combinations of movement disorder, seizures and epilepsy disorder, developmental delay, intellectual disability, and structural malformations of the brain and sometimes other tissues. Patients have a wide range of severities and symptoms. Most commonly, a type of movement disorder experienced by some patients called ‘Paroxysmal Non-kinesigenic Dyskinesia’ (PNKD) manifests as ‘drop attacks,’ where patients temporarily lose control of their muscles and become immobilized. Other terms that may be used to describe these episodes include atonia, akinesia or non-narcoleptic cataplexy.

How many people are affected by the KCNMA1-linked channelopathy?
KCNMA1 variants have a low prevalence in the population because it is a rare disease. Currently, there are approximately 103 patients documented to have KCNMA1 variants associated with the disorder.

How does the syndrome get passed on to future generations?
Questions like this are best answered by a licensed geneticist. Most KCNMA1 variants occur ‘de novo,’ due to a random spontaneous mutation. A few variants have been inherited from a parent.  In most cases, it is thought that one copy of the mutated KCNMA1 variant is enough to result in patient symptoms.