Human amylase gene copy number variation as a determinant of metabolic state

ABSTRACT

Introduction: Humans have multiple genes encoding amylase that are broadly divided into salivary (AMY1) and pancreatic (AMY2) genes. They exhibit some of the greatest copy numbers of any human gene, an expansion possibly driven by increased dietary starch intake. Within the population, amylase gene copy number is highly variable and there is evidence of an inverse association between AMY1 copy number and BMI.

Areas covered: We examine the evidence for the link between AMY1 and BMI, its potential mechanisms, and the metabolic effects of salivary and pancreatic amylase, both in the gastrointestinal tract and the blood.

Expert commentary: Salivary amylase may influence postprandial ‘cephalic phase’ insulin release, which improves glucose tolerance, while serum amylase may have insulin-sensitizing properties. This could explain the favorable metabolic status associated with higher AMY1 copy number. The association with BMI is harder to explain and is potentially mediated by increased flux of undigested starch into the ileum, with resultant effects on short-chain fatty acids (SCFAs), changes in gut microbiota and effects on appetite and energy expenditure in those with low copy number. Future research on the role of amylase as a determinant of metabolic health and BMI may lead to novel therapies to target obesity.

KEYWORDS:

• Obesity
• insulin resistance
• diabetes mellitus
• salivary amylase
• AMY1 copy number
• pancreatic amylase
• AMY2 copy number
• serum amylase
• copy number variation
• cephalic phase insulin release
• CPIR

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosure

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose

Additional information

Funding

This article was not funded.

Notes on contributors

Thomas M. Barber

All authors contributed toward the preparation of this manuscript.