Ataxin 3

Ataxin-3 is a protein that in humans is encoded by the ATXN3 gene.

Clinical significance

Machado-Joseph disease, also known as spinocerebellar ataxia-3, is an autosomal dominant neurologic disorder. The protein encoded by the ATXN3 gene contains (CAG)n repeats in the coding region, and the expansion of these repeats from the normal 13-36 to 68-79 is the cause of Machado-Joseph disease. There is an inverse correlation between the age of onset and CAG repeat numbers. Alternatively spliced transcript variants encoding different isoforms have been described for this gene.

Interactions

Ataxin 3 has been shown to interact with:

• RAD23A,
• RAD23B, and
• VCP.

Model organisms

Model organisms have been used in the study of ATXN3 function. A conditional knockout mouse line called Atxn3^{tm1a(KOMP)Wtsi} was generated at the Wellcome Trust Sanger Institute. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Additional screens performed: - In-depth immunological phenotyping - in-depth bone and cartilage phenotyping

Atxn3 knockout mouse phenotype

Characteristic	Phenotype
All data available at.
Peripheral blood leukocytes 6 Weeks	Normal
Insulin	Normal
Haematology 6 Weeks	Normal
Homozygous viability at P14	Normal
Homozygous Fertility	Normal
Body weight	Normal
Neurological assessment	Normal
Grip strength	Normal
Dysmorphology	Normal
Indirect calorimetry	Normal
Glucose tolerance test	Normal
Auditory brainstem response	Normal
DEXA	Normal
Radiography	Normal
Eye morphology	Normal
Clinical chemistry	Normal
Haematology 16 Weeks	Normal
Peripheral blood leukocytes 16 Weeks	Normal
Heart weight	Normal
Salmonella infection	Normal
Cytotoxic T Cell Function	Normal
Spleen Immunophenotyping	Normal
Mesenteric Lymph Node Immunophenotyping	Normal
Bone Marrow Immunophenotyping	Normal
Epidermal Immune Composition	Normal
Influenza Challenge	Normal

External links

• GeneReviews/NCBI/NIH/UW entry on Spinocerebellar Ataxia Type 3