Table 1. List of monogenic causes of chorea.

Gene	Main associated phenotype	Gene product	Inheritance	Age of onset	Diagnostic clues
HTT	Huntington disease	Huntingtin	AD (CAG expansion)	Childhood to late adulthood	Cognitive decline, psychiatric disturbances Progressive course MRI: caudate nucleus head atrophy
PRNP	HDL1	Prion protein	AD (octapeptide coding repeat expansion)	Adulthood	Dementia and psychiatric features Possible parkinsonism at onset and longer survival than HD
JPH3	HDL2	Junctophilin 3	AD (CAG/CTG expansion)	Adulthood	Parkinsonism may be first manifestation High frequency in people with black African ancestry
TBP	- HDL4 - Spinocerebellar ataxia type 17	TATA box-binding protein	AD (CAG expansion)	Childhood to adulthood	Ataxia and cognitive decline Frequent parkinsonism MRI: cerebellar atrophy
ATN1	Dentatorubral-pallidoluysian atrophy	Atrophin-1	AD (CAG expansion)	Childhood to adulthood	Seizures, myoclonus and cognitive decline MRI: Cerebellar and brainstem atrophy (especially pons) High frequency in Japan
C9orf72	FTD/MND	Chromosome 9 Open Reading Frame 72	AD (GGGGCC expansion)	Childhood to adulthood	Prominent cognitive and psychiatric features Pyramidal signs MRI: diffuse cerebral atrophy
FTL	Neuroferritinopathy	Ferritin light chain	AD	Teenage to late adulthood	Action-specific facial dystonia Reduced ferritin plasma levels MRI: iron deposition in basal ganglia and cortical pencil lining
SLC20A2 PDGFB PDGFRB XPR1	Idiopathic Basal Ganglia Calcification (IBGC)	Na-dependent phosphate transporter type 2 Platelet-derived growth factor βpolypeptide Platelet-derived growth factor receptor, β Xenotropic and polytropic retroviruses receptor	AD	Symptoms: early to late adulthood Calcium deposition: childhood to adolescence	CT scan: basal ganglia, cerebellar dentate nuclei and subcortical white matter calcification
VPS13A	Chorea-acanthocytosis	Chorein	AR	Early adulthood	Severe oromandibular dystonia with lip and tongue biting Head drops Peripheral axonal neuropathy Elevated serum CK MRI: caudate nucleus head atrophy
XK	Macleod syndrome	Kell blood group protein	X-linked recessive	Adulthood	Peripheral sensorimotor neuropathy Cardiomyopathy Elevated serum CK
ATM	Ataxia-telangiectasia	Ataxia-telangiectasia mutated gene	AR	Childhood to adulthood	Oculocutaneous telangiectases Sensorimotor neuropathy Elevated serum alpha-fetoprotein Predisposition to malignancy MRI: cerebellar atrophy
APTX SETX PNKP	Ataxia with oculomotor apraxia (AOA) type 1, 2, and 4	Aprataxin Senataxin Polynucleotide kinase 3’-phosphatase	AR	Childhood to adulthood	Sensorimotor neuropathy Hypoalbuminemia in AOA1 Hypercholesterolemia in AOA1 and AOA4 Elevated alpha-fetoprotein in AOA2 and AOA4 MRI: cerebellar atrophy
RNF216	Gordon-Holmes syndrome	Ring finger protein 216	AR	Adulthood	Hypogonadism MRI: cerebellar atrophy
NKX2-1	NKX2-1-related chorea	Thyroid transcription factor 1	AD/De novo	Infancy	Non-progressive course Hypotonia and early falls Learning difficulties Frequent pulmonary and thyroid dysfunction
ADCY5	ADCY5-related chorea	Adenylate cyclase 5	AD/De novo	Infancy to childhood	Normal cognition Dystonia and myoclonus may become prominent with age Severe diurnal and nocturnal exacerbations Axial hypotonia and delayed milestones in most severe cases
PDE10A	PDE10A-related chorea	Phosphodiesterase 10A	De novo/AR	Infancy to childhood	Delayed milestones and language development and dysarthria in cases with recessive mutations MRI: symmetrical T2-hyperintense bilateral striatal lesions in cases with dominant de novo mutations
GPR88	GPR88-related chorea	G protein-coupled receptor 88	AR	Childhood	Language delay and learning disabilities
GNAO1	Early infantile epileptic encephalopathy type 17 (Ohtahara syndrome)	Gαo	De novo	Infancy to childhood	Progressive and severe movement disorder associated with developmental delay, with or without seizures
FOXG1	Congenital Rett disease	Forkhead Box G1	De novo	Infancy to early childhood	Severe intellectual disability, absent language, acquired microcephaly MRI: corpus callosum abnormalities, frontal or frontotemporal underdevelopment mild cerebellar hypoplasia, and delayed myelination.
SYT1	Severe motor delay and intellectual disability	Synaptotagmin-1	De novo	Infancy	Severe delayed motor development without seizures
SCN8A	- Early infantile epileptic encephalopathy type 13 - BFIS	NaV1.6α-subunit of voltage-gated Na channels	AD/De novo	Infancy to childhood	Paroxysmal dystonia/chorea triggered by sudden movements or emotional stress Focal EEG abnormalities during attacks

AD: autosomal dominant; AR: autosomal recessive; BFIS: Benign familial infantile seizures; HDL: Huntington’s disease-like.