Ma. Honein et al., Family history, maternal smoking, and clubfoot: An indication of a gene-environment interaction, AM J EPIDEM, 152(7), 2000, pp. 658-665
Citations number
55
Categorie Soggetti
Envirnomentale Medicine & Public Health","Medical Research General Topics
Although epidemiologic studies of some birth defects have suggested a gene-
smoking interaction, the possibility of this interaction in clubfoot has no
t been examined. The authors analyzed risk factors among 346 infants with i
solated clubfoot and 3,029 infants without defects from the Atlanta Birth D
efects Case-Control Study. All infants were born during 1968-1980, and moth
ers were interviewed in 1982-1983. The authors examined the family history-
smoking interaction as an indication of a gene-environment interaction. The
y defined "smoking" as smoking any time during the first 3 months of pregna
ncy and "family history" as having a first-degree relative with clubfoot. C
onditional logistic regression (matching variables: race, birth hospital, a
nd birth period) was used to obtain effect estimates. The adjusted odds rat
ios were 1.34 (95% confidence interval (CI): 1.04, 1.72) for smoking only,
6.52 (95% CI: 2.95, 14.41) for family history only, and 20.30 (95% CI: 7.90
, 52.17) for a joint exposure of smoking and family history. The effect est
imate for the joint exposure was higher than would be expected under either
an additive or a multiplicative model of interaction and showed a statisti
cally significant departure from additivity. This study confirms the import
ance of familiar factors and smoking in the etiology of clubfoot and identi
fies a potentially important interaction.