Table 5.

Interactions of DBH -1021TT+TC vs CC with variants of IL1A and IL6 in AD risk

Interaction with	Dataset	Numbers		Power*	Adjusted† synergy factor (95% CI, p)
		Controls	AD
IL1A -889TT vs TC+CC	All	6137	1535	93%	1.9 (1.2-3.1, 0.005)
	North Europe	5678	1078	87%	1.7 (1.02-2.8, 0.04)
	North Spain	459	457	32%	3.4 (0.9-12.3, 0.07)
IL6 -174GG vs GC+CC	All	6161	1565	95%	1.3 (0.98-1.7, 0.07)
	North Europe	5692	1084	88%	1.5 (1.07-2.0, 0.02)
	North Spain	469	481	44%	0.94 (0.5-1.7, 0.85)

The first column indicates the models used to represent the SNPs, IL1A -889T/C and IL6 -174G/C, in the analyses of interactions with DBH -1021C/T.

AD = Alzheimer's disease, DBH = dopamine β-hydroxylase, CI = confidence interval.

* Power to detect a synergy factor of 1.9 (first interaction) or 1.5 (second interaction) at p < 0.05.

^† All analyses controlled for centre, age, sex and genotype of apolipoprotein E ε4.

Results in bold are significant at p < 0.05.