This condition is caused by mutations in a gene called NRCAM, which normally helps brain cells stick together and communicate properly. For the disorder to happen, a person needs to inherit a faulty copy of the gene from both parents. Diagnosis can be made through genetic testing, like whole exome or genome sequencing, or by direct gene sequencing. Different types of mutations have been observed in patients — some that completely stop the gene from working (called "loss-of-function"), and others that just slightly change how it works by changing a single amino acid ("missense" changes). Generally, patients with the more severe form of the condition usually have the loss-of-function mutations, while those with milder symptoms tend to have missense mutations.
NRCAM