The Spinocerebeller Ataxias


The spinocerebellar ataxias are a group of autosomal dominantly inherited ataxias with heterogeneous presentation. Characteristic CAG repeat expansions in the coding sequences at several loci have been detected for certain of these disorders. Hence, a direct DNA test can provide an unequivocal diagnostic result for what are often complex clinical presentations. The loci reponsible for this group of disorders continues to grow and are the subject of research strategies evaluating trinucleotide (especially CAG trinucleotide) repeat expansions. A recent comprehensive clinical and molecular genetic reference is provided by Koshy and Zoghbi (1997), Brain Pathology 7:927-942. Although this is a recent review, it is out of date as the locus for SCA7 has been recently described (David et al. (1997) Nature Genetics 17:65-70; Koob et al. (1998) Nature Genetics 18:72-75.)

The Table below provides a cross-reference of SCA genetic loci and a variety of alternative clinical names. In addition, by clicking on the highlighted OMIM reference number, you will be linked to the appropriate OMIM page. These pages provide current reviews of the genetics and clinical features of these disorders.


Gene Name Locus Alternative Name OMIM Link
SCA 1
6p23
 Spinocerebellar atrophy I; Olivopontocerebellar atrophy I (OPCA 1); Menzel type OPCA
#164400
SCA 2
12q24
 Spinocerebellar atrophy II; Olivopontocerebellar atrophy I, Holguin type; OPCA 2; Spinocerebellar ataxia, Cuban type
#183090
SCA 3
14q24.3-q31
 Spinocerebellar atrophy III; Machado-Joseph Disease; Azorean neurologic disease; Joseph disease; Spinopontine atrophy with nigrospinodentatal degeneration
#183085
#109150
SCA 4
16q22.1
 Spinocerebellar ataxia, autosomal dominant with sensory axonal neuropathy
#600223
SCA 5
11p11-q11
 None
#600224
SCA 6
19q13
 None
#183086
SCA 7
3p21.1-p12
 Olivopontocerebellar atrophy III (OPCA III); OPCA with retinal degeneration; OPCA with macular degeneration and external ophthalmoplegia; ADCA type 2
#164500
SCA 8
10q24
 Infantile-onset spinocerebellar ataxia (IOSCA); spinocerebellar ataxia, infantile, with sensory neuropathy
#271245