X-linked spinocerebellar ataxias, not yet incorporated into formal classification system

Disorder	Distinguishing features	Gene or locus	Protein
FXTAS	Fragile X tremor/ataxia syndrome with intention tremor, parkinsonism, cognitive decline, and atrophy	FMR1	Fragile X mental retardation protein (FMRP) 1
SCAX1	Ataxia (olivopontocerebellar atrophy), hypotonia at birth, motor delay, difficulty standing	ATP2B3	ATPase plasma membrane Ca2+ transporting 3
SCAX2	Ataxia, head tremor, spasticity, cerebellar atrophy	Not yet identified
SCAX3	Ataxia, hypotonia, sensorineural deafness, optic atrophy	Not yet identified
SCAX4	Ataxia, pyramidal tract signs, adult-onset dementia	Not yet identified
SCAX5	Ataxia, neonatal hypotonia, motor delay, dysarthria	Not yet identified

FXTAS: fragile X tremor/ataxia syndrome; SCAX: spinocerebellar ataxia X-linked.

Graphic 133272 Version 1.0