SLC18A3 and Cognitive impairment: Nevertheless, the observation of intrauterine death in a SLC18A3 patient with a homozygous nonsense variant (c.1116C>A, p.Cys372*) accords with lethality of homozygous VAChT knock-out, whereas animals with a 70% reduction of expression levels of VAChT are myasthenic and have cognitive deficits [5,28].