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ATXN7

Synonyms
ADCAII, OPCA3, SCA7, SGF73
External resources
Summary
The autosomal dominant cerebellar ataxias (ADCA) are a heterogeneous group of neurodegenerative disorders characterized by progressive degeneration of the cerebellum, brain stem and spinal cord. Clinically, ADCA has been divided into three groups: ADCA types I-III. ADCAI is genetically heterogeneous, with five genetic loci, designated spinocerebellar ataxia (SCA) 1, 2, 3, 4 and 6, being assigned to five different chromosomes. ADCAII, which always presents with retinal degeneration (SCA7), and ADCAIII often referred to as the 'pure' cerebellar syndrome (SCA5), are most likely homogeneous disorders. Several SCA genes have been cloned and shown to contain CAG repeats in their coding regions. ADCA is caused by the expansion of the CAG repeats, producing an elongated polyglutamine tract in the corresponding protein. The expanded repeats are variable in size and unstable, usually increasing in size when transmitted to successive generations. This locus has been mapped to chromosome 3, and it has been determined that the diseased allele associated with spinocerebellar ataxia-7 contains 37-306 CAG repeats (near the N-terminus), compared to 4-35 in the normal allele. The encoded protein is a component of the SPT3/TAF9/GCN5 acetyltransferase (STAGA) and TBP-free TAF-containing (TFTC) chromatin remodeling complexes, and it thus plays a role in transcriptional regulation. Alternative splicing results in multiple transcript variants.

Variant counts

The variants found in rare patients tested by 3billion are classified and counted according to ACMG guidelines. The variants with over 5% variant frequency in population genome databases ( gnomAD, dbSNP, etc) are excluded.

Pathogenic
6
Likely pathogenic
0
VUS
2,251
Likely benign
8,653
Benign
0

Patient phenotypes

Proportions of phenotypes among 3 patients carrying pathogenic or likely pathogenic variants on ATXN7 gene are displayed below.

Phenotype class
Patients in 3billion (%)
Abnormality of head or neck
33.3%
Abnormality of the genitourinary system
33.3%
Abnormality of the musculoskeletal system
33.3%
Abnormality of the nervous system
33.3%
Abnormal cellular phenotype
0%
Abnormality of blood and blood-forming tissues
0%
Abnormality of limbs
0%
Abnormality of metabolism homeostasis
0%
Abnormality of prenatal development or birth
0%
Abnormality of the breast
0%
Abnormality of the cardiovascular system
0%
Abnormality of the digestive system
0%
Abnormality of the ear
0%
Abnormality of the endocrine system
0%
Abnormality of the eye
0%
Abnormality of the immune system
0%
Abnormality of the integument
0%
Abnormality of the respiratory system
0%
Abnormality of the thoracic cavity
0%
Abnormality of the voice
0%
Constitutional symptom
0%
Growth abnormality
0%
Neoplasm
0%

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