Finding FXTAS in patients with SCA12-like manifestation suggests that TRE in the 5'UTR of the gene is the common cue connecting two disorders with common phenotype of tremor/ataxia.
SCA12 is an autosomal dominant cerebellar ataxia characterized by onset in the fourth decade of life with action tremor of arms and head, mild ataxia, dysmetria, and hyperreflexia.
Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7.
The expansion of a CAG repeat upstream of the PP2APR55beta gene has been recently reported as a novel cause of a dominantly inherited ataxia (SCA12) in a kindred with limb tremor as an early feature.