ESPE2015 Poster Category 3 Late Breaking Posters (15 abstracts)
aDepartment of Paediatrics, G. dAnnunzio University, Chieti, Italy; bDepartment of Pharmacy, G. dAnnunzio University, Chieti, Italy; cUnit of General Pathology, Aging Research Center, G. dAnnunzio University Foundation, Chieti, Italy
Background: Genome-wide association studies have identified more than 60 SNPs associated with BMI. Additional genetic variants, such as copy number variations (CNV), have also been implicated in the pathogenesis of obesity. Recently, the highly polymorphic CNV in the salivary amylase (AMY1) gene has been associated with obesity risk in adults.
Objective and hypothesis: To assess the potential association between AMY1 copy number and BMI in a population of Caucasian school children.
Methods: 748 children (356 boys, mean age (±S.D.): 8.4±1.4 years) underwent anthropometric assessments (height, weight, and BMI) and collection of salivary samples for DNA extraction. AMY1 copies were evaluated by quantitative PCR.
Results: In the whole study population median AMY1 copies was 8 (range 227). A progressive decrease in BMI z-score was found across AMY1 quartiles (Q): Q1Q4, 0.64±1.04 vs 0.33±1.09 vs 0.56±1.01 vs 0.45±1.12, P=0.03. Post-hoc analysis revealed a significant difference in BMI z-score between AMY1 Q1 and Q2 (P=0.028).
After dividing the study population in BMI z-score deciles, AMY1 copy number was lower in children in the top decile (BMI z-score >1.8, n=74) than in the lower deciles: (BMI z-score <1.8, n=674): 8 vs 9, P=0.019. In addition, all children with >17 AMY1 copies had a BMI z-score in the lower deciles of the population distribution. In a logistic regression model, a significant and inverse association was found between AMY1 copies and BMI z-score in the top decile: 0.911 (95% CI: 0.8420.985).
Conclusions: In this first pediatric-only, population-based study, a higher AMY1 copy number emerged to be protective against obesity. These data confirm previous findings from adult studies and support a potential role of a higher expression of the salivary amylase, implicated in the first step of starch digestion, in protecting from excess weight gain. This finding could be of particular relevance for populations, such as ours, with a high dietary starch intake.