Table 1:

Repeat expansion diseases by location and pathomechanism.

Disease	Abbrev.	Inheritance	Host gene	Repeat motif	Location	Somatic instability	LOF	RBP sequestration	AUG-initiated protein GOF	RAN translation	Other
Unverricht-Lundborg disease	EPM1	AR	CSTB	CCCCGCCCCGCG	promoter		+
Baratela-Scott syndrome	BSS	AR	XYLT1	CGG	promoter/5’ UTR	+	+
Glutaminase deficiency	GAD	AR	GLS	CAG	5’ UTR	+	+
Spinocerebellar ataxia type 12	SCA12	AD	PPP2R2B	CAG	5’ UTR				+
Fragile XE syndrome	FRAXE	XL	AFF2	CCG	5’ UTR	+	+
Jacobsen syndrome	FRA11B	AD	CBL2	CCG	5’ UTR						+ a
Intellectual disability, associated with fragile site FRA2A	FRA2A	AD	AFF3	CGG	5’ UTR	+	+
Intellectual disability, associated with fragile site FRA12A	FRA12A	AD	DIP2B	CGG	5’ UTR		+
Fragile X syndrome	FXS	XL	FMR1	CGG	5’ UTR	+	+
Fragile X-associated primary ovarian insufficiency	FXPOI	XL	FMR1	CGG	5’ UTR	+				+
Fragile X-associated tremor/ataxia syndrome	FXTAS	XL	FMR1	CGG	5’ UTR	+		+		+
Neuronal intranuclear inclusion disease	NIID	AD	NOTCH2NLC	CGG	5’ UTR
Oculopharyngodistal myopathy 1	OPDM1	AD	LRP12	CGG	5’ UTR	+
Oculopharyngodistal myopathy 2	OPDM2	AD	GIPC1	CGG	5’ UTR
Oculopharyngeal myopathy with leukoencephalopathy	OPML	AD	LOC642361/NUTM2B-AS1	CGG/CCG	lncRNA	+
Cerebellar ataxia, neuropathy, vestibular areflexia syndrome	CANVAS	AR	RFC1	AAGGG	intron
Spinocerebellar ataxia type 10	SCA10	AD	ATXN10	ATTCT	intron	+		+
X-linked dystonia-parkinsonism	XDP	XL	TAF1	CCCTCT	intron	+	+
Myotonic dystrophy type 2	DM2	AD	CNBP	CCTG	intron	+		+		+
Autism spectrum disorder, associated with fragile site FRA7A	FRA7A	AD	ZNF713	CGG	intron	+	+
Fuchs endothelial corneal dystrophy	FECD	AD	TCF4	CTG	intron	+		+		+
Friedreich’s ataxia	FA	AR	FXN	GAA	intron	+	+
Spinocerebellar ataxia type 36	SCA36	AD	NOP56	GGCCTG	intron			+		+
C9ORF72 amyotrophic lateral sclerosis/frontotemporal dementia	C9 ALS/FTD	AD	C9ORF72	GGGGCC	intron	+	+	+		+
Spinocerebellar ataxia type 31	SCA31	AD	BEAN1/TK2	TGGAA/TTCCA	intron			+		+
Familial adult myoclonic epilepsy 1	FAME1	AD	SAMD12	TTTCA	intron	+
Familial adult myoclonic epilepsy 2	FAME2	AD	STARD7	TTTCA	intron
Familial adult myoclonic epilepsy 3	FAME3	AD	MARCH6	TTTCA	intron	+
Familial adult myoclonic epilepsy 4	FAME4	AD	YEATS2	TTTCA	intron
Familial adult myoclonic epilepsy 6	FAME6	AD	TNRC6A	TTTCA	intron
Familial adult myoclonic epilepsy 7	FAME7	AD	RAPGEF2	TTTCA	intron
Spinocerebellar ataxia type 37	SCA37	AD	DAB1	TTTCA	intron
Dentatorubral-pallidoluysian atrophy	DRPLA	AD	ATN1	CAG	CDS	+		+	+
Huntington’s disease	HD	AD	HTT	CAG	CDS	+		+	+	+
Spinal and bulbar muscular atrophy	SBMA	XL	AR	CAG	CDS	+	+		+
Spinocerebellar ataxia type 1	SCA1	AD	ATXN1	CAG	CDS	+	+		+
Spinocerebellar ataxia type 2	SCA2	AD	ATXN2	CAG	CDS		+	+	+
Spinocerebellar ataxia type 3	SCA3	AD	ATXN3	CAG	CDS	+		+	+
Spinocerebellar ataxia type 6	SCA6	AD	CACNA1A	CAG	CDS				+
Spinocerebellar ataxia type 7	SCA7	AD	ATXN7	CAG	CDS	+			+
Spinocerebellar ataxia type 17	SCA17	AD	TBP	CAG	CDS	+	+		+
Pseudoachondroplasia and multiple epiphyseal dysplasia	PSACH/MED	AD	COMP	GAC	CDS		+		+
Blepharophimosis, ptosis, and epicanthus inversus syndrome	BPES	AD	FOXL2	GCN	CDS		+
Cleidocranial dysplasia	CCD	AD	RUNX2	GCN	CDS		+
Congenital central hypoventilation syndrome	CCHS	AD	PHOX2B	GCN	CDS	+ c	+
Hand-foot-genital syndrome	HFGS	AD	HOXA13	GCN	CDS	+ c	+
Holoprosencephaly 5	HPE	AD	ZIC2	GCN	CDS	+ c	+
Oculopharyngeal muscular dystrophy	OPMD	AD	PABPN1	GCN	CDS		+		+
Synpolydactyly 1	SPD	AD	HOXD13	GCN	CDS		+
X-linked hypopituitarism	XH	XL	SOX3	GCN	CDS		+
X-linked intellectual disability b	XLID	XL	ARX	GCN	CDS	+ c	+
Spinocerebellar ataxia type 8	SCA8	AD	ATXN8OS/ATXN8	CTG/CAG	3’ UTR/CDS			+	+	+
Myotonic dystrophy type 1	DM1	AD	DMPK	CTG	3’ UTR	+		+		+
Huntington’s disease-like 2	HDL2	AD	JPH3	CTG	3’ UTR		+	+

^aFRA11B expansion causes hypermethylation and is associated with chromosomal breakage and deletion of the telomeric end of 11q.²⁷¹

^bLoss-of-function mutations in ARX are associated with a spectrum of clinical phenotypes, including X-linked infantile spasm syndrome, X-linked lissencephaly with ambiguous genitalia, X-linked myoclonic epilepsy and intellectual disability, Partington syndrome, Ohtahara syndrome, and Proud syndrome.²⁷²

^cSomatic mosaicism documented in carriers only.^273–276