How is "Abdominal Skinfold Thickness" encoded by the genome?
Measurement of skinfold thickness with a skinfold caliper is a simple and inexpensive technique to rank individuals in terms of relative total fatness, or to assess subcutaneous fat at various regions of the body. Skinfold testing provides a more accurate body assessment than body mass index (BMI), which is a measurement of relative body weight but not body composition, because lean mass weighs far more than fat.
A polymorphism in the vicinity of the NYD-SP18 gene has been reported to be highly related to BMI. Recent studies reported that the effect of the NYD-SP18 rs6971091 polymorphism on BMI values is even greater than that of the FTO variants that have a well-established effect on body weight. Additionally, the intronic variant rs4854344 within the TMEM18 gene is, based on the results of a GWA (genome-wide association) study, a very strong predictor of BMI/body weight in whites. Original results have also been replicated in children/adolescents. However, a few studies have examined the possible effect of this gene in determining the success of interventions leading to body weight loss in children/adolescents.
The aim of this large study was to assess how the NYD-SP18 (rs6971091) and TMEM18 (rs4854344 ) gene variants affect the efficacy of a 1-month weight loss program in children/adolescents. In total, 684 unrelated, white, non-diabetic children were genotyped. The weight loss program comprised individualized dietary changes aimed at achieving a caloric intake of 5000 kJ for children aged 8–10 years old and 7000 kJ for adolescents 11–15 years old. Children performed 5 units of supervised physical activity daily, totalling at least 120 minutes of endurance training. The exercise program consisted of aerobic and resistance training complemented by playing ball games, swimming, and brisk walking. Anthropometric and biochemical examinations were performed before and after 4 weeks of the program. Results showed that the mean weight loss achieved was 5.20±2.02 kg. AA homozygotes of rs6971091 had significantly higher abdominal skinfold value before and after the intervention, while no significant associations between BMI decrease and the both NYD-SP18 and TMEM18 variants were found. Associations between all anthropometrical and biochemical changes and genes remained non-significant after data were adjusted for sex, age, and baseline values.
Generally, directly comparing intervention studies focused on body weight loss is very difficult, principally due to the different study protocols used. This study, in which patients are virtually isolated and given an identical menu, minimizes the intra-study variability caused by different energy intake values. Also, the intensity and frequency of physical activity performed was highly variable in other studies, but uniform in our study. The fact that both these factors were strictly controlled in this study is undoubtedly a strong point. Unfortunately, however, such a strict regime cannot be sustained over the long term. If you would like to know more about this research, you can read the study;
https://pubmed.ncbi.nlm.nih.gov/30341978/
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