Objective: Low birth weight is suggested to be a risk factor for a wide variety of negative outcomes, including low educational attainment, but the role of cognition-related genetic influences on this association remains unclear. The objective of this study was to study whether variation in the dopamine receptor gene (dopamine receptor D2 polymorphism, rs1800497) modifies the association between birth weight and educational attainment in adulthood.
Methods: We studied the association between birth weight (range: 1440-4980 g) and educational attainment in 659 men and 832 women aged 27 to 39. Birth weight, gestational age, and parental education were assessed at ages 6 to 18. The genotyping was performed using TaqMan 5' nuclease assay.
Results: After adjustment for age, parental education, and gestational age, birth weight was associated with educational attainment in men with A1/A1 or A1/A2 (n = 245) genotype but not in men carrying A2/A2 (n = 414) genotype. In women, no moderating effect of dopamine receptor D2 polymorphism was found.
Conclusions: Dopamine receptor D2 genotype is suggested to modify the association between birth weight and adulthood educational attainment over the whole birth weight range so that carriers of A1 allele capitalize on optimal birth weight, whereas a low birth weight seems to be a risk among them. These data support the hypothesis that the effect of birth weight on educational attainment depends on genetic influences. Gender-related difference may refer to an environmental effect (ie, to a better goodness-of-fit between girls' school behaving and expectations of school) that may mask a genetic effect.