Salivary Amylase Gene Copy Number Relates with BMI Z-Score and with Response to Lifestyle Intervention for Children with Overweight and Obesity.

The prevalence of childhood obesity has risen significantly, with numerous associated health risks. Emerging research suggests a potential role for genetic factors; particularly, copy number variations (CNVs) of the gene () may influence obesity through dietary behavior and metabolic regulation. This study aimed to examine the relationship between BMI z-score, dietary intake, and salivary gene copy number (CN) in children with overweight and obesity, and to assess the relationship between CN and the impact of lifestyle intervention on these parameters. The study included 90 children aged 2-6 years with overweight or obesity. Participants were randomized into either a parent support intervention group or a standard care control group. Anthropometric measurements, dietary intake, and salivary gene copy number were assessed at baseline and after a 9-month intervention. Positive correlations were found between gene copy number, BMI z-score, and carbohydrate intake, suggesting a potential role of this gene in dietary behavior-related obesity. The parent support intervention led to significant reductions in children's BMI, BMI z-score, and energy and macronutrient intake compared to standard care. Although there was no direct association between copy number and changes in BMI z-score, higher copy numbers were associated with greater reductions in polyunsaturated fatty acid intake. These findings highlight an interaction between salivary gene copy number, dietary intake, and obesity in children. These results support the relevance of genetic factors in obesity-related dietary patterns and emphasize the effectiveness of targeted family-based lifestyle interventions.