No Evidence for Association of BMI with Salivary Amylase Gene Copy Number in the UK 1958 Birth Cohort.

Abstract

In a 2014 publication, evidence was presented supporting the association of BMI with the copy number of the salivary amylase 1 (AMY1) gene, with an unprecedented effect size of -0.15 kg/m² (SE 0.02) per copy of AMY1. Most well-powered attempts to reproduce these findings have not been successful. However, because of different study designs, a significant association may still apply under restricted conditions such as in particular age groups. This study specifically tested the BMI-AMY1 association at different age points in the same individuals using longitudinal BMI information from participants in the UK 1958 Birth Cohort study. This study measured the AMY1 copy number by paralogue ratio tests in genomic DNA and by using array comparative genomic hybridization data. BMI data from 1958 Birth Cohort participants were available from eight different age points between 7 and 50 years. No evidence, even at nominal significance, was found for association of the AMY1 copy number with BMI at any age point in approximately 1,400 members of the 1958 Birth Cohort or in 2,835 people from two disease cohorts from the Wellcome Trust Case Control Consortium. The results do not support an association between BMI and AMY1 copy number at any age point.