ATXN2

This gene belongs to a group of genes that is associated with microsatellite-expansion diseases, a class of neurological and neuromuscular disorders caused by expansion of short stretches of repetitive DNA. The protein encoded by this gene has two globular domains near the N-terminus, one of which contains a clathrin-mediated trans-Golgi signal and an endoplasmic reticulum exit signal. The encoded cytoplasmic protein localizes to the endoplasmic reticulum and plasma membrane, is involved in endocytosis, and modulates mTOR signals, modifying ribosomal translation and mitochondrial function. The N-terminal region of the protein contains a polyglutamine tract of 14-31 residues that can be expanded in the pathogenic state to 32-200 residues. Intermediate length expansions of this tract increase susceptibility to amyotrophic lateral sclerosis, while long expansions of this tract result in spinocerebellar ataxia-2, an autosomal-dominantly inherited, neurodegenerative disorder. Genome-wide association studies indicate that loss-of-function mutations in this gene may be associated with susceptibility to type I diabetes, obesity and hypertension. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2016]

Ataxin 2

Involved in EGFR trafficking, acting as negative regulator of endocytic EGFR internalization at the plasma membrane.

Negative regulation of receptor internalization Source: UniProtKB
P-body assembly Source: UniProtKB
Regulation of cytoplasmic mRNA processing body assembly Source: GO_Central
Regulation of translation Source: UniProtKB
RNA metabolic process Source: UniProtKB
RNA transport Source: UniProtKB
Stress granule assembly Source: UniProtKB

Cytoplasm

Spinocerebellar ataxia 2 (SCA2): The disease is caused by variants affecting the gene represented in this entry. SCA2 is caused by expansion of a CAG repeat resulting in about 36 to 52 repeats in some patients. Longer expansions result in earlier the expansion, onset of the disease. Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to cerebellum degeneration with variable involvement of the brainstem and spinal cord. SCA2 belongs to the autosomal dominant cerebellar ataxias type I (ADCA I) which are characterized by cerebellar ataxia in combination with additional clinical features like optic atrophy, ophthalmoplegia, bulbar and extrapyramidal signs, peripheral neuropathy and dementia. SCA2 is characterized by hyporeflexia, myoclonus and action tremor and dopamine-responsive parkinsonism. In some patients, SCA2 presents as pure familial parkinsonism without cerebellar signs.
Amyotrophic lateral sclerosis 13 (ALS13): Disease susceptibility is associated with variants affecting the gene represented in this entry. An increased risk for developing amyotrophic lateral sclerosis seems to be conferred by CAG repeat intermediate expansions greater than 23 but below the threshold for developing spinocerebellar ataxia.
A neurodegenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord, resulting in fatal paralysis. Sensory abnormalities are absent. The pathologic hallmarks of the disease include pallor of the corticospinal tract due to loss of motor neurons, presence of ubiquitin-positive inclusions within surviving motor neurons, and deposition of pathologic aggregates. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of the cases.