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FB2026_01
,
released March 12, 2026
This report describes autosomal recessive spinocerebellar ataxia 13, a subtype of autosomal recessive spinocerebellar ataxia.. The human gene implicated is GRM1, which encodes BAF nuclear assembly factor 1, GRM1 is also associated with spinocerebellar ataxia 44 (MIM:617691), which has an autosomal dominant inheritance pattern. There is one low-scoring fly ortholog, Dmel\mGluR, the only Drosophila metabotropic glutamate receptor, for which multiple genetic reagents, including loss of function alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated.
Wild-type Hsap\GRM1 has been introduced into flies, but has not been used to model disease.
Mushroom body-specific RNAi knockdown of Dmel\mGluR resulted in flies moving less frequently and more slowly after startling, and in flies exhibiting a decrease in spontaneous motor behavior.
[updated June 2024 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, AUTOSOMAL RECESSIVE 13; SCAR13](https://omim.org/entry/614831)
[GLUTAMATE RECEPTOR, METABOTROPIC, 1; GRM1](https://omim.org/entry/604473)
Autosomal recessive spinocerebellar ataxia-13 (SCAR13) is an autosomal recessive neurologic disorder characterized by delayed psychomotor development beginning in infancy. Affected individuals show mildly to profoundly impaired intellectual development with poor or absent speech as well as gait and stance ataxia and hyperreflexia. Most individuals also have eye movement abnormalities. Brain MRI shows cerebellar atrophy and ventriculomegaly (Guergueltcheva et al., 2012, pubmed:22901947). [from MIM:614831; 2024.06.12]
Autosomal recessive spinocerebellar ataxia-13 (SCAR13) is caused by homozygous mutation in the GRM1 gene on chromosome 6q24. [from MIM:614831; 2024.06.12]
GRM1 encodes a metabotropic glutamate receptor that functions by activating phospholipase C. [provided by RefSeq, May 2013]
Many to one (many human to 1 Drosophila); GRM1 has one low-scoring Drosophila ortholog, mGluR.
High-scoring ortholog of human GRM3, moderate scoring ortholog of human GRM2, low-scoring ortholog of GRM1, GRM4, GRM6, GRM7, GRM8 (1 Drosophila to many human).