Table 3.

Maternal smoking by GABBR2 haplotypes among 1022^a case- and control-mothers.

			OR of smokingc			No. of cigarettes smoked
Haplotypeb	Haplotype frequency (%)	One or two copies	OR	95% CI	P valuee	Coefficientd	95% CI	P valuee
C-a-c	14	One	0.9	0.6–1.2	0.58	0.6	−0.7–1.9	0.32
		Two	1.3	0.5–3.4		3.0	−1.3–7.2
t-a-c	12	One	0.8	0.6–1.1	0.41	1.1	−0.4–2.5	0.36
		Two	0.8	0.3–2.3		0.3	−2.9–3.5
C-G-c	23	One	0.8	0.6–1.1	0.33	−0.3	−1.6–0.9	0.39
		Two	0.8	0.4–1.4		−1.5	−3.6–0.7
C-a-T	11	One	1.0	0.7–1.4	0.64	0.3	−1.1–1.8	0.76
		Two	0.5	0.2–1.9		0.9	−1.7–3.6
t-a-T	12	One	1.1	0.8–1.5	0.03	0.5	−0.9–1.9	0.33
		Two	0.1	0.0–0.6		−1.6	−4.5–1.2
C-G-T	28	One	Ref.	-	-	Ref.	-	-
		Two

^aHaplotypes could be predicted for a total of 1022 mothers from the offspring-parent trios using HAPLIN.

^bHaplotypes of rs1435252-rs3780422-rs2779562.

^cOdds ratio of maternal smoking during the first trimester of pregnancy estimated by frequency-weighted logistic regression, using the probability distribution of possible haplotypes for each mother as predicted by HAPLIN from the offspring-parent trios.

^dRegression analysis of number of cigarettes smoked per day during the first trimester of pregnancy by frequency-weighted linear regression, using the probability distribution of possible haplotypes for each mother as predicted by HAPLIN from the offspring-parent trios.

^eP values for effect of one or two copies of the haplotype.

Abbreviations: GABBR2, gamma-aminobutyric acid B receptor 2; OR, odds ratio; CI, confidence interval; ref, reference haplotype.