Background

Prior studies have shown that single nucleotide polymorphisms (SNPs) within the brain-derived neurotrophic factor (BDNF) and fat mass and obesity-associated (FTO) genes are associated with obesity, but data are limited on the effects of these SNPs on appetite and food intake, especially their role as mediators for obesity in a predominantly African American pediatric cohort with severe obesity. We hypothesized that among minority youth with obesity, carriers of obesity-risk alleles will have more severe obesity and higher intake of fat than non-carriers.

Methods

We studied 573 youth enrolled in an urban outpatient multidisciplinary weight management clinic. Appetite was assessed using the caregiver-reported Dykens Hyperphagia Questionnaire. Habitual dietary intake was estimated using the self-reported Block Food Frequency Questionnaire. Patients were genotyped using TaqMan SNP assays for FTO intronic rs9939609, BDNF intronic rs12291063, and BDNF Val66Met rs6265. Differences in dietary intake by genotype were assessed by ANCOVAs adjusting for age, sex, race, and BMI-Z.

Results

Participants were age 12.3±3.5y, BMI 147±29% of the 95th percentile, 60% female, and 60% African American. Total intake (kcal/kg total body weight) was similar across genotypes for all 3 SNPs studied. FTO rs9939609 minor A allele was associated with increased BMI-Z only in females (p=.03). BDNF rs6265 minor T allele was associated with higher hyperphagia score (p=.04). BDNF rs6265 T allele was associated with higher BMI-Z only in African Americans (p=.002). Carriers of BDNF rs6265 T allele (p=.03) and FTO rs9939609 A allele (p=.02) reported higher cheese intake. Carriers of BDNF intronic rs12291063 minor C allele reported higher fried chicken intake (p=.003).

Conclusions

Among children with severe obesity, carriers of FTO and BDNF SNPs may be predisposed to greater appetite and increased consumption of high fat foods. Genetic variants may potentially may be beneficial to consider for individualized weight management.