Background: Genetic variability of metabolic enzymes may influence the effect of cigarette smoking on intrauterine development and on early neonatal events.
Aims: To investigate the role of adenosine deaminase genetic polymorphism on the effect of smoking on neonatal bilirubinemia and developmental parameters.
Study design: Analysis of association between adenosine deaminase phenotypes and neonatal developmental parameters. Prospective study of serum bilirubin level in relation to adenosine deaminase phenotype.
Methods: We have studied 360 consecutive newborn infants from the Caucasian population of Rome. Serum bilirubin concentration was determined at birth and every 24 h for the first five days.
Results: Overall maternal smoking is associated with a slight decrease in the incidence of phototherapy (13.4% in non smoking vs 11.7% in smoking mothers) and with a reduction of birth weight (3374 g in non smoking mothers vs 3133 g in smoking mothers). There is a significant interaction between smoke and adenosine deaminase. While in non smoking mothers the incidence of phototherapy in carriers of ADA 2 allele is higher than in ADA 1 phenotype, in infants from smoking mothers the pattern is reversed and the incidence of phototherapy in carriers of ADA 2 allele is lower than in infants with ADA 1 phenotype. Other neonatal bilirubin parameters follow a similar pattern of interaction between smoking and ADA. The negative effect of smoke on birth weight is much more evident in infant with ADA 1 phenotype than in those carrying the ADA 2 allele.
Conclusions: The data suggest that ADA phenotype modifies the effect of smoking on developmental and bilirubin parameters.