Supplementary Material for: FTO genotypes (rs9939609 T>A) are associated with increased added sugar intake in healthy young adults

Introduction: Single-nucleotide polymorphism (SNP) rs9939609 in the FTO gene has been associated with dietary intake and appetite traits mainly in participants with obesity, however it remains widely unexplored in normal weight participants. Thus, the aims of this study were 1) to compare the changes in subjective appetite sensations, ghrelin, and insulin concentrations according to the SNP rs9939609 T>A in FTO and 2) to compare dietary intake between rs9939609 genotype groups in normal weight young participants.
Methods: We conducted a quasi-experimental study involving 88 normal-weight participants to analyze subjective perception of appetite, hormonal response for hunger and satiety, and dietary intake according to the rs9939609 SNP. Participants received a standardized single breakfast. Visual Analogue Scales (VAS) were utilized for assessing the subjective perception of appetite at fasting and immediately after breakfast and at 30, 60, 90, and 120 minutes postprandially. Glucose, lipid profile, ghrelin, and insulin were measured at fasting and at 120 minutes after breakfast. Dietary intake was assessed with a 3-day food record. The SNP was determined by allelic discrimination with TaqMan probes. To compare dietetic, biochemical, and the subjective appetite sensations, Student T test, ANCOVA test, and the repeated measures ANOVA were used. The linear regression model and the linear mixed model were used for the association analysis. Pearson correlation was used to test the correlation between two quantitative variables.
Results: A total of 88 people participated, 81.8% were female, with a mean BMI of 21.8 ± 2.0 kg/m2 and a mean age of 20.6 ± 2.0. Genotype frequencies of the rs9939609 SNP were 52 % for the TT allele and 48 % for the TA/AA. The subjective perception of appetite named hunger, fullness, satiety, desire to eat, and prospective food consumption were similar between genotypes of the rs9939609. Participants with the TA/AA genotype showed a higher intake of added sugar (p=0.039) than TT participants. No differences were found in ghrelin, insulin, glucose, or lipid parameters between genotypes.
Conclusion: Carriers of the A allele from FTO gene SNP rs9939609 may have an increased preference for foods, specifically for added sugars.

引言：FTO基因中的单核苷酸多态性（Single-nucleotide polymorphism, SNP）rs9939609主要与肥胖人群的膳食摄入及食欲特征相关，但目前针对体重正常人群的相关研究仍未得到充分探索。因此，本研究的两大目标为：1）对比携带FTO基因rs9939609 T>A位点多态性的受试者的主观食欲感受、饥饿素（ghrelin）及胰岛素浓度变化；2）对比体重正常青年人群中不同rs9939609基因型组的膳食摄入差异。
方法：本研究纳入88名体重正常受试者，开展类实验研究，以依据rs9939609 SNP位点分析受试者的食欲主观感知、饥饿与饱腹感的激素反应及膳食摄入情况。所有受试者均进食标准化单次早餐。研究采用视觉模拟评分法（Visual Analogue Scales, VAS），分别于空腹状态、早餐后即刻及餐后30、60、90、120分钟评估受试者的食欲主观感知。于空腹时及早餐后120分钟采集血样，检测血糖、血脂谱、饥饿素（ghrelin）及胰岛素水平。膳食摄入情况通过3天食物记录法进行评估。rs9939609位点多态性采用TaqMan探针进行等位基因分型检测。为比较膳食、生化指标及主观食欲感受的组间差异，本研究分别采用t检验、协方差分析（ANCOVA）及重复测量方差分析；关联分析则采用线性回归模型与线性混合模型；两定量变量间的相关性采用Pearson相关分析进行检验。
结果：本研究共纳入88名受试者，其中女性占比81.8%，平均年龄为20.6±2.0岁，平均身体质量指数（Body Mass Index, BMI）为21.8±2.0 kg/m²。rs9939609 SNP位点的基因型频率分别为：TT型52%，TA/AA型48%。不同rs9939609基因型受试者的饥饿感、饱腹感、满足感、进食欲望及预期食物摄入量等主观食欲感知指标均无显著组间差异。TA/AA基因型受试者的添加糖摄入量显著高于TT型受试者（p=0.039）。不同基因型受试者的饥饿素、胰岛素、血糖及血脂参数均无显著组间差异。
结论：携带FTO基因rs9939609位点A等位基因的受试者，可能对食物具有更高的偏好性，尤其偏好添加糖类食品。