Table 1.

Summary of important genetic causes of chorea syndromes

Condition	Synonym	Inheritance	Position	Gene	Number of Exons	Triplet Repeat Disorderb	Regions of High Penetrance
HD		AD	4p16	HTT	67b	√	Venezuela and worldwide
HDL1		AD	20p13	PRNP	2	√
HDL2		AD	16q24	JPH3	5b	√	Black Africa
HDL4	SCA17	AD	6q27	TBP1	8b	√
Spinocerebellar ataxias, i.e, SCA1, SCA2, SCA3, SCA8, SCA12		AD				√
DRPLA	NOD, HRS	AD	12p13	ATN1	10b	√	Japan
C9orf72 repeat expansions	Typically associated with FTD–ALS	AD	9p21	C9orf72	12c		Finnland, Sweden, Spain
Neuroferritinopathy		AD	19q13	FTL1 a	4		Cumbrian region of northern England
Benign hereditary chorea	Thyroid‐lung syndrome	AD	14q13	TITF1	3
Benign hereditary chorea, type 2		AD	Linked to chr. 8q21	–	–
ADCY5‐associated chorea	Familial dyskinesia with facial myokymia	AD	3q21	ADCY5	21
Primary familial brain calcification	Idiopathic basal ganglia calcification, Fahr's disease	AD	8p11	SLC20A2	11
			5q32	PDGFRB	23
			22q12	PDGFB	7
			1q25	XPR1	25
Chorea‐acanthocytosis	Levine–Critchley syndrome	AR	9q21	VPS13A	73
McLeod syndrome		x‐linked	Xp21	XK	3
HDL3		AR	4p15	–	–
RNF216‐mediated neurodegeneration		AR	7p22	RNF216 (TRIAD3)	17
FRRS1L‐mediated chorea		AR	9q31	FRRS1L	5
Wilson disease	Hepatolenticular degeneration	AR	13q14	ATP7B	21
Ataxia telangiectsia	ATM syndrome	AR	11q22	ATM	66
Aceruloplasminemia		AR	3q24	CP	23

^aDisease‐causing triplet repeat located in exon 1 (HD and HDL2), exon 3 (HDL4/SCA17), exon 5 (DRPLA).

^bAlso associated with hereditary hyperferritinemia cataract syndrome.

^cExpanded hexanucleotide repeat (GGGGCC) located between the noncoding exons 1a and 1b of C9orf72.

HD, Huntington's disease; AD, autosomal dominant; HDL, Huntington‐like disorder; HTT, huntingtin; SCA 17, spinocerebellar ataxia 17; DRPLA, Dentatorubral‐pallidoluysian atrophy; NOD, Naito‐Oyanagi disease; HRS, Haw River Syndrome; FTD–ALS, frontotemporal dementia–amyotrophic lateral sclerosis; AR, autosomal recessive.