Parental and child genetic contributions to obesity traits in early life based on 83 loci validated in adults: the FAMILY study.

BACKGROUND: The genetic influence on child obesity has not been fully elucidated.

OBJECTIVE: This study investigated the parental and child contributions of 83 adult body mass index (BMI)-associated single-nucleotide polymorphisms (SNPs) to obesity-related traits in children from birth to 5 years old.

METHODS: A total of 1402 individuals were genotyped for 83 SNPs. An unweighted genetic risk score (GRS) was generated by the sum of BMI-increasing alleles. Repeated weight and length/height were measured at birth, 1, 2, 3 and 5 years of age, and age-specific and sex-specific weight and BMI Z-scores were computed.

RESULTS: The GRS was significantly associated with birthweight Z-score (P = 0.03). It was also associated with weight/BMI Z-score gain between birth and 5 years old (P = 0.02 and 6.77 × 10-3 , respectively). In longitudinal analyses, the GRS was associated with weight and BMI Z-score from birth to 5 years (P = 5.91 × 10-3 and 5.08 × 10-3 , respectively). The maternal effects of rs3736485 in DMXL2 on weight and BMI variation from birth to 5 years were significantly greater compared with the paternal effects by Z test (P = 1.53 × 10-6 and 3.75 × 10-5 , respectively).

CONCLUSIONS: SNPs contributing to adult BMI exert their effect at birth and in early childhood. Parent-of-origin effects may occur in a limited subset of obesity predisposing SNPs.