Abstract
The FTO rs9939609 risk allele is linked to risk of obesity. Whether causality involves
fatty acid (FA) metabolism remains to be fully investigated in adults with obesity.
We tested for associations of the risk allele with the FA composition of android and
gynoid subcutaneous adipose tissue. We recruited 95 participants with obesity class
2 and 3 and without diabetes, median BMI 42.8 (25th, 75th percentiles: 39.5, 46.5) kg/
m2
. Participants carried no (TT, n=33), one (AT, n=31), or two (AA, n=31) copies of
the FTO risk allele. Biopsies were obtained by aspiration and total FA composition
determined by gas chromatography-mass spectrometry (GC-MS). In the cohort overall, there were no significant genotype associations with any single FA. In males with
the TT allele, mass of oleic acid (18:1n-9) in the gynoid depot was higher compared
with the AT allele when corrected for depot size. We interpret these findings with
caution due to the small numbers of males with the TT genotype. Disregarding genotype, in the cohort overall, proportions of saturated FAs were higher, and proportions
of monounsaturated FAs lower in android versus gynoid adipose tissue, confirming
previous studies. We found previously unreported sex-related differences in FA composition (weight %) and content (weight % corrected for depot mass). Our findings on
FTO genotype are generally negative; observations to the contrary require confirmation as does the non-genetic and novel results on sex-related differences.