Table 2.

Included studies global intellectual functioning

Authors	N	Age	Comparison	Subdomain(s)	Instrument(s)	Results
Ross et al, 2008	47 XXY	4‐9;11 years 10‐17;8 years	Normed scores	GCA	DAS	Older boys < younger boys
Ross et al, 2009	93 XXY 21 XYY	4‐18 years	Control group	GCA	DAS	XXY = XYY < controls
				VP		XXY = XYY < controls
				NVP		XXY = XYY < controls
				Spatial cluster		XXY < XYY = controls
Cordeiro et al, 2012	95 XXY 29 XYY	4‐18 years	Normed scores	VIQ‐PIQ Gap	DAS, WASI or WISC	XXY VIQ < PIQ XYY VIQ < PIQ
Bruining et al, 2009	47 XXY	6‐19 years	Normed scores	FSIQ	WISC or WASI	XXY < controls
				PIQ		XXY < controls
				VIQ		XXY < controls
Ratcliffe, 1999	19 XXY 19 XYY 16 XXX	6‐8 years	Control group	PIQ	WISC	XXY < controls XYY < controls XXX < controls
				VIQ		XXY < controls XYY < controls XXX < controls
Rovet et al, 1995; 1996	21‐29 XXY	6‐18 years	Control group	PIQ	WISC or WASI	XXY < controls
				VIQ		XXY < controls
				VIQ‐PIQ Gap		XXY VIQ < PIQ
Netley, 1986	73 XXY 32 XXX 28 XYY	Mxxy = 10.3 years Mxxx = 10.5 years Mxyy = 9.5 years	Normed scores	FSIQ	WISC or WASI	XXY < controls XXX < controls XYY n.s.
				PIQ		XXY n.s. XYY n.s. XXX < controls
				VIQ		XXY < controls XXX < controls XYY n.s.
				VIQ‐PIQ Gap		XXX VIQ < PIQ

Abbreviations: DAS, Differential Ability Scales; FSIQ, full scale intelligence quotient; GCA, General Conceptual Ability; n.s., no significant differences; IQ, intelligence; NVP, Nonverbal Performance; PIQ, performance intelligence quotient; WASI, Wechsler Abbreviated Scale of Intelligence; VIQ, verbal intelligence quotient; VP, Verbal Performance; WISC, Wechsler Intelligence Scale for Children.