Table 1.

Overview of clinical trials mentioned in the text

	Target cell/injection	Disease	Transgene	Vector	Refs.
Ex vivo	T-lymphocytes	ADA-SCID	ADA	Gammaretroviral	Blaese et al (1995)
	HSC	ADA-SCID	ADA	Gammaretroviral	Aiuti et al (2002)
		SCID-X1	IL2Rγc	Lentiviral	Cavazzana-Calvo et al (2000)
		WAS	WASP	(±SIN design)	Boztug et al (2010) and Aiuti et al (2013)
		X-CGD	gp91phox		Ott et al (2006)
	HSC	β-Thalassaemia	β-Globin	SIN-lentiviral	Cavazzana-Calvo et al (2010)
	HSC	X-ALD	ABCD1	SIN-lentiviral	Cartier et al (2009)
	HSC	MLD	ARSA	SIN-lentiviral	Biffi et al (2013)
	HSC	HIV	ZFNs targeting CCR5 (knock out)	Adenoviral	Burnett et al (2012) and Lee et al (2013)
	Hepatocytes	Familial hypercholesterinemia	LDL receptor	Gammaretroviral	Grossman et al (1994)
	T-lymphocytes	B-cell malignancies	Anti-CD19 CAR	SIN lentiviral	Kalos et al (2011), Kochenderfer et al (2010) and Porter et al (2011)
				SB-transposon	Swierczek et al (2012)
	Keratinocytes	Epidermolysis bullosa	laminin 5 β3	Gammaretroviral	Mavilio et al (2006)
In vivo	Intratumoural	Head and neck squamous cell carcinoma	p53	Adenovirus (Gendicine®)	Wilson (2005) and Shi & Zheng (2009)
	Intramuscular	LPLD	LPL	AAV1 (Glybera®)	Bryant et al (2013) and Kastelein et al (2013)
	Systemic/portal vein	OTCD	OTC	Adenovirus	Raper et al (2002, 2003)
	Subretinal	LCA	RPE65	AAV2	Bainbridge et al, 2008; Hauswirth et al, 2008; Maguire et al, 2008
	Intracerebral (subthal. nucl.)	Parkinson's disease	GAD	AAV2	Kaplitt et al (2007) and LeWitt et al (2011)
	Intracerebral	Canavan disease	ASPA	AAV2	Leone et al (2012)
	Intramuscular, systemic/portal vein	Haemophila B	FIX	AAV2	Kay et al (2000)
				AAV2, AAV8	Manno et al (2006)
					Nathwani et al (2011)
	Coronary artery infusion	Heart failure	SERCA2a	AAV1	Jessup et al (2011)