BAIAP2 rs8079781, postnatal smoking exposure, and emotional problems in Japanese children aged 5 years: the Kyushu Okinawa Maternal and Child Health Study.

BAIAP2 might be implicated in neurodevelopmental and psychiatric conditions via abnormal development of human cerebral asymmetry. The present prebirth cohort study examined the relationship between BAIAP2 single nucleotide polymorphism (SNP) rs8079781 and the risk of behavioral problems in Japanese children aged 5 years. Subjects were 1175 mother-child pairs. Emotional problems, conduct problems, hyperactivity problems, peer problems, and low prosocial behavior were assessed using the parent version of the Strengths and Difficulties Questionnaire. Compared with the CC genotype of SNP rs8079781, at least one T allele was significantly inversely related to childhood emotional problems: the adjusted OR was 0.68 (95% CI 0.46-0.998, P = 0.049). Nevertheless, this significant inverse association disappeared after adjustment for multiple comparisons (adjusted P = 0.245). No associations were observed between SNP rs8079781 and childhood conduct problems, hyperactivity problems, peer problems, or low prosocial behavior. An independent positive relationship was observed between smoking in the household during the first year of life and emotional problems in children with the CC genotype, but not in those with at least one T allele (P for interaction = 0.04). This study is the first to show that at least one T allele of SNP rs8079781 was independently associated with a reduced risk of emotional problems in children aged 5 years, but this inverse association fell below significance after adjustment for multiple comparisons. The influence of smoking in the household during the first year of life might rely on rs8079781.