Differential genetic susceptibility to child risk at birth in predicting observed maternal behavior

Abstract

This study examined parenting as a function of child medical risks at birth and parental genotype (dopamine D4 receptor; DRD4). Our hypothesis was that the relation between child risks and later maternal sensitivity would depend on the presence/absence of a genetic variant in the mothers, thus revealing a gene by environment interaction (GXE). Risk at birth was defined by combining risk indices of children's gestational age at birth, birth weight, and admission to the neonatal intensive care unit. The DRD4-III 7-repeat allele was chosen as a relevant genotype as it was recently shown to moderate the effect of environmental stress on parental sensitivity. Mothers of 104 twin pairs provided DNA samples and were observed with their children in a laboratory play session when the children were 3.5 years old. Results indicate that higher levels of risk at birth were associated with less sensitive parenting only among mothers carrying the 7-repeat allele, but not among mothers carrying shorter alleles. Moreover, mothers who are carriers of the 7-repeat allele and whose children scored low on the risk index were observed to have the highest levels of sensitivity. These findings provide evidence for the interactive effects of genes and environment (in this study, children born at higher risk) on parenting, and are consistent with a genetic differential susceptibility model of parenting by demonstrating that some parents are inherently more susceptible to environmental influences, both good and bad, than are others.

Figure 1. Mean maternal sensitivity based on risk at birth and the presence/absence of maternal DRD4-III 7-repeat allele.

Mean levels (and standard errors) of observed maternal sensitivity as a function of child risk at birth (low, medium, and high) and the presence or absence of maternal DRD4-7R allele. Mothers who are non-carriers of the 7 allele showed no difference in levels of sensitivity under conditions of high, medium, and low risk at birth. Mothers who are carriers of the 7 allele were more sensitive to low-risk children and less sensitive to high-risk children.