Beneficial effect of a high number of copies of salivary amylase AMY1 gene on obesity risk in Mexican children.
OBJECTIVE
Childhood obesity is a major public health problem in Mexico, affecting one in every three children. Genome-wide association studies identified genetic variants associated with childhood obesity, but a large missing heritability remains to be elucidated. We have recently shown a strong association between a highly polymorphic copy number variant encompassing the salivary amylase gene (AMY1 also known as AMY1A) and obesity in European and Asian adults. In the present study, we aimed to evaluate the association between AMY1 copy number and obesity in Mexican children.


METHODS
We evaluated the number of AMY1 copies in 597 Mexican children (293 obese children and 304 normal weight controls) through highly sensitive digital PCR. The effect of AMY1 copy number on obesity status was assessed using a logistic regression model adjusted for age and sex.


RESULTS
We identified a marked effect of AMY1 copy number on reduced risk of obesity (OR per estimated copy 0.84, with the number of copies ranging from one to 16 in this population; p = 4.25 × 10(-6)). The global association between AMY1 copy number and reduced risk of obesity seemed to be mostly driven by the contribution of the highest AMY1 copy number. Strikingly, all children with >10 AMY1 copies were normal weight controls.


CONCLUSIONS
Salivary amylase initiates the digestion of dietary starch, which is highly consumed in Mexico. Our current study suggests putative benefits of high number of AMY1 copies (and related production of salivary amylase) on energy metabolism in Mexican children.
Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico.
María A
MA
Mejía-Benítez
Amélie
A
Bonnefond
Loïc
L
Yengo
Marlène
M
Huyvaert
Aurélie
A
Dechaume
Jesús
J
Peralta-Romero
Miguel
M
Klünder-Klünder
Jaime
J
García Mena
Julia S
JS
El-Sayed Moustafa
Mario
M
Falchi
Miguel
M
Cruz
Philippe
P
Froguel
D015992:Body Mass Index; D050260:Carbohydrate Metabolism / Q000235:genetics*; D002648:Child; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D006801:Humans; D016015:Logistic Models; D008297:Male; D008800:Mexico / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology / Q000235:genetics*; D011634:Public Health; D055291:Salivary alpha-Amylases / Q000235:genetics / Q000378:metabolism*
C524788:AMY1A protein, human; D055291:Salivary alpha-Amylases