Table 1.

CSR phenotype in cells deficient for various DNA repair factors that might be involved in the NHEJ pathway during CSR.

protein	model	CSR efficiency	proliferation defect	GL transcription	type of junctions	significant shift towards use of microhomology	frequency of junctional mutationsa	references
ATM	human	reduced (IgA)	n.a.b	n.a.	Sμ–Sα	yes (7.2 versus 1.8 bp)	reduced	Pan et al. (2002)
					Sμ–Sγ	yes (2.5 versus 1.2 bp)	reduced
	mouse	reduced (IgA, IgG1, IgG2a, IgG3, IgE)	no	normal	Sμ–Sγ1	yes (2.6 versus 1.2 bp)	n.a.	Lumsden et al. (2004)
		7–50% of controls
	mouse	reduced (IgG1, IgG2b, IgG3)	no	normal	Sμ–Sγ1	no (1.9 versus 2.0 bp)	reduced	Reina-San-Martin et al. (2004)
		30% of controls
H2AX	mouse	reduced (IgG1)	no	normal	n.a.	n.a.	n.a.	Petersen et al. (2001)
		24–50% of controls
	mouse	reduced (IgG3)	no	n.a.	n.a.	n.a.	n.a.	Celeste et al. (2002)
		30% of controls
	mouse	reduced (IgG1)	no	normal	Sμ–Sγ1	no (1.8 versus 1.7 bp)	reduced (n.s.)c	Reina-San-Martin et al. (2003)
MDC1	mouse	reduced (IgG1)	no	n.a.	n.a.	n.a.	n.a.	Lou et al. (2006)
		50–75% of controls
53BP1	mouse	reduced (IgG1)	no	normal	n.a.	n.a.	n.a.	Ward et al. (2004)
		7% of controls
	mouse	reduced (all Ig classes)	no	normal	Sμ–Sγ1	no (0.9 versus 1.1 bp)	reduced	Manis et al. (2004)
		2–10% of controls
	mouse	n.a.	n.a.	n.a.	Sμ–Sγ1	no (2.5 versus 2.0 bp)	normal	Reina-San-Martin et al. (2007)
NBS	human	reduced (IgA and IgG)	n.a.	n.a.	Sμ–Sα	yes (3.6 versus 1.8 bp)	normal	Pan et al. (2002) and Lahdesmaki et al. (2004)
					Sμ–Sγ	yes (2.3 versus 1.2 bp)	normal
	mouse	reduced (IgG1 and IgG3)	no	normal	Sμ–Sγ1	no (2.9 versus 2.3 bp)	normal	Kracker et al. (2005)
		approx. 50% of controls
	mouse	reduced (IgG1)	yes	normal	Sμ–Sγ1	no (1.4 versus 0.8 bp)	normal	Reina-San-Martin et al. (2005)
		approx. 50% of controls
Mre11	human	reduced (IgA and IgG)	n.a.	n.a.	Sμ–Sα	no (2.6 versus 1.8 bp)	reduced C to T	Lahdesmaki et al. (2004)
					Sμ–Sγ	no (1.8 versus 1.2 bp)	n.a.
ATR	human	normal (IgA and IgG)	n.a.	n.a.	Sμ–Sα	yes (3.0 versus 1.8 bp)	reduced	Pan-Hammarstrom et al. (2006)
					Sμ–Sγ	yes (1.8 versus 1.2 bp)	reduced (n.s.)
Ku70	mouse	impaired (IgG1, IgG2b, IgG3 and IgE) not detectable	yes	normal	n.a.	n.a.	n.a.	Manis et al. (1998)
Ku80	mouse	impaired (IgG1 and IgG3)	yes	normal	n.a.	n.a.	n.a.	Casellas et al. (1998)
		not detectable
DNA-PKcs	mouse	reduced (IgE)	no	normal	n.a.	n.a.	n.a.	Rolink et al. (1996)
		100- to 250-fold less
	mouse	impaired (all the isotypes except IgG1) not detectable	no	normal	Sμ–Sγ1	no	n.a.	Manis et al. (2002)
	mouse	reduced (IgA, IgG1, IgG3 and IgG2b)	no	n.a.	n.a.	n.a.	n.a.	Bosma et al. (2002)
		30–50% of controls
	mouse	reduced (IgG1, IgG2a, IgG2b, IgG3, IgE)	yes	n.a.	Sμ–SγSμ–Sϵ	yes (3.4 versus 2.3 bp)	reduced(reduced C)	Cook et al. (2003)
		40–70% of controls
	mouse	near normal (IgG2b, IgG3, and IgA)	n.a.	n.a.	n.a.	n.a.	n.a.	Kiefer et al. (2007)
DNA ligase IV	human	reduced (IgA and IgG)	n.a.	n.a.	Sμ–Sα	yes (9.8 versus 1.8 bp)	reduced	Pan-Hammarstrom et al. (2005)
					Sμ–Sγ	no (1.3 versus 1.2 bp)	normal
	mouse	reduced (IgG1 and IgE)	n.a.	n.a.	?	yes	n.a.	Yan et al. (2007)
		50% of controls
XRCC4	mouse	reduced (IgG1 and IgG3)	no	yes	Sμ–Sγ1	no	n.a.	Soulas-Sprauel et al. (2007)
		40–75% of controls
	mouse	reduced (IgG1 and IgG3)	no	n.a.	Sμ–Sγ	yes	reduced	Yan et al. (2007)
		20–50% of controls			Sγ–Sϵ
					Sμ–Sϵ

^aMutations around junctions, ±15 bp for human study and ±50 bp for mouse study.

^bn.a., not analysed.

^cn.s., not significant.