The serotonin transporter gene-linked polymorphic region (5-HTTLPR) may moderate an individual's response to stress. This study analyzes how the infant 5-HTTLPR may interact with the level of their mother's emotional state to affect infant irritability.
A prospective study was carried out with 314 newborns and their mothers. Infant irritability and the mother emotional state were evaluated at 8 and 32 weeks after childbirth. These variables were correlated with the 5-HTTLPR genotypes of both the infants and their mothers. The irritability score of infants with the s allele of 5-HTTLPR showed a linear relationship with their mother's anxiety at both 8 (P= 0.009) and 32 weeks (P= 0.008). In Infants carrying the ll genotype irritability was independent of their mother's anxiety.
This study provided evidence that the promoter 5-HTTLPR polymorphism could moderate the influence of the mother's anxiety on infant irritability.