OBJECTIVES: Monoamine oxidase A (MAOA) modulates metabolism of serotonin and 
dopamine metabolism, neurotransmitters involved in regulation of appetite and 
food intake. The gene coding for MAOA contains a 30-bp tandem repeat (uVNTR) 
polymorphism in its promoter region that has been previously identified to be 
associated with obesity with mixed findings in the literature. Our goals were to 
replicate the population effects of this functional polymorphism on obesity 
risk, and to further explore gender differences and interaction effects with 
negative stressors.
METHODS: Analyses were conducted with data on genotypes, measured weight and 
height, and self-reported behavioural characteristics among 1101 Chinese 
adolescents 11-15 years old living in Wuhan, China.
RESULTS: Girls with the high-activity allele had significantly lower body mass 
index (BMI; β = -0.25 ± 0.98, P = 0.011) compared to those with the low activity 
allele. Experience of negative familial stressors (e.g., death or illness of 
family members, hit or scolded by parents and increased quarrelling with 
parents, parents argued frequently) significantly weakened this protective 
genetic effect on BMI (P for interaction = 0.043). Stratified analyses showed a 
significant protective genetic effect on BMI only within the stratum of low 
stress level (β = -0.44 ± 0.14, P = 0.002). No similar effect was observed among 
boys.
CONCLUSIONS: Our findings confirm the genetic effects of MAOA uVNTR polymorphism 
on BMI in a Chinese adolescent population and suggest potential genetic 
interactions with negative familial stressors.