Table 1.

Genes affected by polyglutamine expansion and the function of their protein products where known. In some cases repeat expansion affects more than one gene product.

Polyglutamine expansion diseases
Disease name	Products of expanded gene	Wild-type number of repeats (repeat sequence)	Repeat expansion in disease	Protein function
Huntington disease (HD)	Huntingtin	6-34 (CAG)	36-121	Transcriptial repressor, membrane trafficking, endocytosis
Spinal and bulbar muscular atrophy (SBMA)/Kennedy's disease	Androgen receptor	9-36 (CAG)	38-62	Nuclear receptor, Androgen response
Dentatorubral-pallidoluysian atrophy	Atrophin 1	7-34 (CAG)	49-88	Nuclear receptor corepressor, Transcriptional corepressor
SCA1	Ataxin-1, alt-ATXN1	6-39 (CAG)	40-82	RNA processing, Transcription factor, Transcriptional corepressor, general repressor of transcription
SCA2 and amyotrophic lateral sclerosis (ALS)	Ataxin-2	15-24 (CAG)	27-33 for ALS, 32-200 for SCA2	RNA binding protein
SCA3, Machado-Joseph disease	Ataxin-3	13-36 (CAG)	61-84	Transcription factor, Transcriptional coactivator, Transcriptional repressor, Histone H2B deubiquitinase
SCA6	α1A voltage-dependent calcium channel subunit, and α1ACT	4-18 (CAG)	19-33	Voltage-gated calcium channel, Transcription factor
SCA7	Ataxin-7	4-35 (CAG)	36-460	Integral member of SAGA complex, regulation of histone acetylation and ubiquitination.
SCA17	TATA box binding protein (TBP)	25-42 (CAG)	47-63	General transcription factor, member of TFIID complex