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Genotype associated with high-risk body fat patterns in black, white obese children
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The FADS1 genotype was associated with an unfavorable body composition and high-risk body fat distribution patterns in black and white children with severe obesity, according to study results presented at the 2018 AGA James W. Freston Conference.
“We conducted this study because we noticed that most of our patients eat modern western diets which contain lots of refined sugars, carbohydrates and high fat,” Webb A. Smith, PhD, an assistant professor of pediatrics at The University of Tennessee Health Science Center and an exercise physiologist at Le Bonheur Children’s Hospital, told Healio Gastroenterology and Liver Disease. “These are well documented to increase the risk of numerous medical conditions including obesity, heart disease and diabetes. However, we also noticed that not all patients with these eating habits develop these health complications. We wanted to determine if we could identify factors that may explain why patients respond differently to unhealthy dietary patterns.”
The researchers recruited children with obesity who presented to Le Bonheur Children’s Hospital Healthy Lifestyle Clinic for participation in the study.
A medical provider evaluated each child as part of routine clinical care. The researchers then reviewed the patients’ clinical diagnoses and assessed body composition and anthropometrics.
Blood samples were obtained for routing clinical testing and remaining blood was banked before discard. Banked samples were used to perform FADS1 genotyping using a FADS1 Taqman SNP genotyping assay.
The main aim of the study, according to Smith, was to evaluate FADS1 variants and associations with metabolic health, and body composition in children with severe obesity.
The researchers conducted genotyping on 288 black (66% girls; body fat 47% ± 6%) and 132 white (59% girls; body fat 48% ± 7%) children with obesity.
Genotype frequencies were 95.8% GG, 2.4% GT, and 1.8% TT in black children and 75.0% GG, 22.7% GT, and 2.3% TT in white children.
Body fat percentage (P = .001) and visceral fat area (P < .001) were significantly higher in black children who were considered high metabolizers (GG risk allele) after stratifying by race and adjusting for age and sex.
White children who had a GG risk allele also had significantly higher body fat percentage (P = .005) and visceral fat area (P < .001) compared with patients who had GT or TT genotypes.
There were significant differences in proportion of children diagnosed with elevated triglyceride, abnormal liver function, and elevated LDL by FADS1 (GG vs. GT and TT) genotype (P < .01), but no association with low HDL or insulin resistance.
“The study confirmed what we expect from adult studies in that African Americans are more likely to be high metabolizers than Caucasians,” Smith said. “In this pilot project, we found that in our group of 441 children with severe obesity that the high metabolizers (GG risk allele) had significantly higher body fat, and in particular high-risk visceral body fat. Visceral body fat is more concerning since it has been linked to higher risks of cardiovascular and metabolic complication. When we looked at metabolic health, the African American children who were high metabolizers had significantly higher rates of elevated LDL, triglycerides and abnormal liver function.”
The results are significant, according to Smith, because the identified risk allele is more likely to impact black children and may explain part of the elevated risk for metabolic health complications.
Once confirmed, the results could provide direction for precision nutrition counseling, according to Smith.
“The high metabolizer group would likely need to limit overall polyunsaturated fatty acids (PUFA) intake as well as focus heavily on balancing omega 6 and omega 3 intake,” Smith said. “While low metabolizers would likely need to increase overall PUFA intake while also focusing on balanced intake. Additionally, these results may be useful for determining how to screen and care for patients by better understanding risk of developing metabolic complications and facilitating early treatment.” – by Ryan McDonald
Reference:
Smith WA, et al. Association of FADS1 genotype with metabolic health and body composition in children with obesity. Presented at: 2018 AGA James W. Freston Conference; Arlington, Va.; Aug. 18-19, 2018.
Disclosures: Smith reports no relevant financial disclosures.