Smoking as a product of gene–environment interaction

Figures & data

Figure 1.  A line-chart of the relationship between the serotonin transporter gene and the quality of family relations in association with the Fagerstrom Nicotine Dependence Index. Homozygous for the long allele (LL), Heterozygous (LS), Homozygous for the short allele (SS).

Table I.  Logistic regression models of 1) 5-HTTLPR genotype, 2) quality of family relations, 3) model adjusted for 5-HTTLPR and quality of family relations, and 4) gene and environment interaction in relation to smoking among adolescents.

	OR	95.0% CI for OR	P
1) 5-HTTLPR
LL (ref)
LS	3.34	1.63–6.83	0.001
SS	0.68	0.28–1.70	0.41
Nagelkerke R^2=0.141
2) Quality of family relations
Good quality of family relations (ref)
Poor quality of family relations	4.26	2.13–8.50	<0.001
Nagelkerke R^2=0.13
3) Adjusted model
LL (ref)
LS	3.23	1.56–6.99	0.001
SS	0.73	0.28–1.91	0.53
Good quality of family relations (ref)
Poor quality of family relations	4.09	1.97–8.49	<0.001
Nagelkerke R^2=0.24
4) Final interaction model
LL–Good relation (ref)
LS–Good relation	2.83	1.18–6.75	0.019
SS–Good relation	0.57	0.17–1.86	0.35
LL–Poor relation	2.73	0.78–9.57	0.12
LS–Poor relation	13.04	4.90–42.84	<0.001
SS–Poor relation	3.41	0.77–15.05	0.11
Nagelkerke R^2=0.24

Homozygous for the long allele (LL), Heterozygous (LS), Homozygous for the short allele (SS).

Figure 2.  A line-chart of the relationship between the serotonin transporter gene and the quality of family relations in association with proportion of individuals with cotinine levels above the median in the total sample.

Table II.  Logistic regression models of gene and environment interaction in relation to nicotine and cotinine among adolescents.

	OR	95.0% CI for OR	P
Nicotine: Final interaction model
LL—Good relation (ref)
LS—Good relation	1.16	0.54–2.59	0.71
SS—Good relation	1.12	0.45–2.82	0.80
LL—Poor relation	3.18	0.94–10.72	0.06
LS—Poor relation	3.21	1.19–8.64	0.02
SS—Poor relation	2.17	0.53–8.79	0.28
Nagelkerke R^2=0.07
Cotinine: Final interaction model
LL—Good relation (ref)
LS—Good relation	0.85	0.28–2.54	0.76
SS—Good relation	2.77	0.93–8.22	0.07
LL—Poor relation	4.11	1.15–14.73	0.03
LS—Poor relation	4.30	1.44–12.77	0.009
SS—Poor relation	2.26	0.47–10.95	0.31
Nagelkerke R^2=0.12