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FB2026_01
,
released March 12, 2026
This report describes spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 2 (SCAN2), one of several spinocerebellar ataxias with axonal neuropathy described in OMIM (see MIM:PS607250). This disease is also described as ataxia with oculomotor apraxia 2 (AOA2) and was formerly named spinocerebellar ataxia autosomal recessive 1 (SCAR1).
The human gene implicated in this disease is Senataxin (SETX), which encodes a probable RNA/DNA helicase involved in diverse aspects of RNA metabolism and DNA repair. There is a single ortholog in Drosophila, Setx, for which RNAi-targeting constructs and an allele caused by insertional mutagenesis have been generated. The SETX gene is also implicated in a second disease, amyotrophic lateral sclerosis 4 (see FBhh0000611.
Multiple UAS constructs of the human Hsap\SETX gene have been introduced into flies, including wild-type and variants associated with disease. Variant(s) implicated in human disease tested (as transgenic human gene, SETX): the R1363X variant form has been introduced into flies; this variant is associated with SCAN2.
The Drosophila Setx gene has not been genetically characterized.
[updated Jul. 2020 by FlyBase; FBrf0222196]
Autosomal recessive cerebellar ataxias (ARCA) are a heterogeneous group of rare neurological disorders involving both central and peripheral nervous system, and in some case other systems and organs, and characterized by degeneration or abnormal development of cerebellum and spinal cord, autosomal recessive inheritance and, in most cases, early onset occurring before the age of 20 years (Palau and Espinos, 2006; pubmed:17112370).
The hereditary ataxias are a group of genetic disorders characterized by slowly progressive incoordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs. [from Gene Reviews, Hereditary Ataxia Overview; pubmed:20301317; 2017.06.16]
See also Jayadev and Bird, 2013 (pubmed:23538602).
Autosomal recessive spinocerebellar ataxia is a neurologic disorder characterized by onset of progressive gait difficulties, eye movement abnormalities, and dysarthria in the first or second decade of life (summary, Dy et al, 2105; pubmed:26224725). [from MIM:609270; 2020.07.13]
Spinocerebellar ataxia with axonal neuropathy is an autosomal recessive neuromuscular disorder typically characterized by onset in the first or second decade of gait disturbance, slowly progressive distal muscle weakness, and axonal sensorimotor neuropathy with distal sensory impairment. [from MIM:218387, MIM:607250; 2020.07.14]
[SPINOCEREBELLAR ATAXIA, AUTOSOMAL RECESSIVE, WITH AXONAL NEUROPATHY 2; SCAN2](https://omim.org/entry/606002)
[SENATAXIN; SETX](https://omim.org/entry/608465)
Autosomal recessive spinocerebellar ataxia-1 is a neurodegenerative disorder characterized by juvenile onset of progressive cerebellar ataxia, axonal sensorimotor peripheral neuropathy, and increased serum alpha-fetoprotein. Oculomotor apraxia is a common but inconsistent finding, found in about 50% of patients; hence this disorder is sometimes referred to as 'ataxia-oculomotor apraxia-2' (AOA2). [from MIM:606002; 2017.09.12]
Autosomal recessive spinocerebellar ataxia-1 (SCAR1) is caused by homozygous or compound heterozygous mutation in the SETX gene. [from MIM:606002; 2017.09.12]
SETX (Senataxin) encodes a probable RNA/DNA helicase involved in diverse aspects of RNA metabolism, DNA repair, and genomic integrity. [Gene Cards, SETX; 2017.09.12]
Moreira et al. (2004; pubmed:14770181) suggested that senataxin may have both RNA and DNA helicase activities and that senataxin acts in the DNA repair pathway, like several other proteins defective in autosomal recessive cerebellar ataxias. [from MIM:608465; 2017.09.12]
One to one: 1 human to 1 Drosophila.
Moderate-scoring ortholog of human gene SETX (1 Drosophila to 1 human); Dmel\Setx shares 21% identity and 36% similarity with the human gene.