Table 2.

Summary of genetic screening studies systematically investigating patients with HD phenocopies^a

	Reference	No. of Patients Screened	Genes Screened								No. of Patients (%) in Whom a Definite Diagnosis Could Be Established	Diagnosis Reached
			PRNP (Prion/HDL1)	JPH3 (HDL2)	TBP (HDL4/SCA17)	ATN1 (DRPLA)	SCA1, 2 and 3	C9orf72	Ferritin	Other
1	Stevanin et al.11 Brain 2003	252	+	+	+	+					4 (1.6)	2 with HDL2, 2 with SCA17
2	Keckarevic et al.13 Int J Neurosci 2005	48	+	+					+		None	–
3	Costa Mdo et al.14 J Hum Gen 2006	107	+	+	+	+				2 candidate genes: CREBBP and POU3F2	None	–
4	Wild et al.12 Mov Disord 2008	285	+	+	+	+	+		+	FXN (Friedreich Ataxia)	8 (2.8)	5 with HDL4, 1 with Prion disease, 1 with HDL2, 1 with Friedreich ataxia
5	Sulek‐Piatkowska et al.15 Neurol Neurochir Pol 2008	224		+	+	+					1 (0.44)	1 with SCA17
6	Rodrigues et al.16 Arquivos de neuro‐psiquiatria 2011	29		+	+	+	+			VPS13A (chorea‐acanthocytosis)	5 (17.2)	3 with HDL2, 2 with ChAc
7	Koutsis et al.17 J Neurol 2012	21		+	+	+	+			SCA8, SCA12	1 (4.8)	1 with SCA8
8	Moss et al.40 Neurology 2014	514						+			10 (1.9)	10 with C9orf72
9	Kostic et al.73 J Neurol 2014	39						+			1 (2.6)	1 with C9orf72
10	Koutsis et al.74 Neurobiol Aging 2015	40						+			2 (5)	2 with C9orf72
TOTAL		1,559a									33 (2.1)

^aIt remains unclear in how far the cohort reported by Moss et al., 2014, includes the 285 patients studied by Wild et al., 200812; the studies were performed at the same center.

PRNP, prion protein gene; HD, Huntington's disease; HDL, Huntington's disease‐like disorder; SCA 17, spinocerebellar ataxia 17.