Table 2:

Studies of in-vivo molecular brain imaging of dopaminergic systems in 22q11.2 deletion syndrome

	Psychotic or non-psychotic illness	Radioligand	Presynaptic or postsynaptic	Main findings
14 22q11.2 deletion syndrome (4 male, 10 female), 16 healthy controls (5 male, 11 female)	No history of psychotic illness	[18F]-DOPA	Presynaptic	Significantly increased capacity of dopamine synthesis in 22q11.2 deletion syndrome89
13 22q11.2 deletion syndrome (8 male, 5 female), 12 healthy controls (8 male, 4 female)	Psychotic illness in seven (54%) of 13 patients with 22q11.2 deletion syndrome	[11C]-DTBZ	Presynaptic	Significantly increased binding of [11C]-DTBZ in 22q11.2 deletion syndrome in 12 patients without Parkinson’s disease; severely reduced binding in one patient with Parkinson’s disease75
12 22q11.2 deletion syndrome (4 male, 8 female), 16 healthy controls (4 male, 12 female)	No history of psychotic illness	[18F]-Fallypride	Postsynaptic	No association between dopamine release and amount of reward in 22q11.2 deletion syndrome in contrast to healthy controls90
15 22q11.2 deletion syndrome (Met 3 male and 7 female, Val 3 male and 2 female)	No history of psychotic illness	[123I]-IBZM	Postsynaptic	Significantly higher availability of D2/3 receptors in Val carriers91
12 22q11.2 deletion syndrome (5 male, 7 female),* 12 healthy controls (5 male, 7 female)	No history of psychotic illness	[123I]-IBZM	Postsynaptic	No differences in availability of D2/3 receptors92

All studies investigated striatal dopamine. Met=low activity COMT¹⁵⁸ allele. Val=high activity COMT¹⁵⁸ allele.

^*Same patients with 22q11.2 deletion syndrome as in Boot and colleagues.⁹¹