ATP2B3 and essential thrombocythemia: SCAX1 (OMIM#302500, http://omim.org/entry/302500) was initially described by Bertini et al. as a neurological disorder characterized by hypotonia at birth, delayed motor development, difficulty standing, cerebellar fits (reminiscent of ET observed in the shaker rat), dysarthria, and slow eye movements followed by ataxia in the first years of life (Bertini et al., 2000).