SCN2A and Familial paroxysmal ataxia: For example, SCN2A mutations that lead to gain of function or loss of function of the encoded sodium voltage-gated channel Nav1.2 can manifest as a spectrum of phenotypes, such as seizure disorders [7], intellectual disability [8], autism spectrum disorder [9], episodic ataxia [10], and schizophrenia [11], with different phenotypic combinations, including one report of overlap of all phenotypes in the same individual [12].