Low AMY1 Gene Copy Number Is Associated with Increased Body Mass Index in Prepubertal Boys

PLoS One. 2016 May 5;11(5):e0154961. doi: 10.1371/journal.pone.0154961. eCollection 2016.

Abstract

Background: Genome-wide association studies have identified more than 60 single nucleotide polymorphisms associated with Body Mass Index (BMI). Additional genetic variants, such as copy number variations (CNV), have also been investigated in relation to BMI. Recently, the highly polymorphic CNV in the salivary amylase (AMY1) gene, encoding an enzyme implicated in the first step of starch digestion, has been associated with obesity in adults and children. We assessed the potential association between AMY1 copy number and a wide range of BMI in a population of Italian school-children.

Methods: 744 children (354 boys, 390 girls, mean age (±SD): 8.4±1.4years) underwent anthropometric assessments (height, weight) and collection of saliva samples for DNA extraction. AMY1 copies were evaluated by quantitative PCR.

Results: A significant increase of BMI z-score by decreasing AMY1 copy number was observed in boys (β: -0.117, p = 0.033), but not in girls. Similarly, waist circumference (β: -0.155, p = 0.003, adjusted for age) was negatively influenced by AMY1 copy number in boys. Boys with 8 or more AMY1 copy numbers presented a significant lower BMI z-score (p = 0.04) and waist circumference (p = 0.01) when compared to boys with less than 8 copy numbers.

Conclusions: In this pediatric-only, population-based study, a lower AMY1 copy number emerged to be associated with increased BMI in boys. These data confirm previous findings from adult studies and support a potential role of a higher copy number of the salivary AMY1 gene in protecting from excess weight gain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Mass Index
  • Child
  • DNA Copy Number Variations / genetics*
  • DNA-Binding Proteins / genetics*
  • Digestion / genetics
  • Female
  • Gene Dosage / genetics*
  • Genome-Wide Association Study / methods
  • Humans
  • Male
  • Obesity / genetics
  • Polymorphism, Single Nucleotide / genetics
  • Saliva / metabolism
  • Starch / genetics
  • Transcription Factors / genetics*
  • Waist Circumference / genetics

Substances

  • DNA-Binding Proteins
  • MYCBP protein, human
  • Transcription Factors
  • Starch

Grant support

This study was supported in part by a grant from the Italian Ministry of Education, University and Research (MIUR): PRIN 2008SWXEAX. At the time of the study, MLM was supported by a “L’Oréal Italia per le Donne e la Scienza” (For Women in Science) fellowship. The authors confirm that the study funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.