Objective: To determine whether 2 single nucleotide polymorphisms (SNPs) in the obesity genes the fat mass and obesity associated gene (FTO) and the insulin induced gene 2 (INSIG2) are associated with class III, or morbid, obesity in patients undergoing bariatric weight loss operations.
Design: Retrospective analysis of genotype and clinical data.
Setting: Large rural tertiary care health system.
Patients: A total of 707 adult patients with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of at least 40 undergoing open or laparoscopic Roux-en-Y gastric bypass operations for morbid obesity or its comorbid medical problems at Geisinger Medical Center, Danville, Pennsylvania.
Results: The mean BMI in the predominantly white female cohort was 51.2. Approximately 21% of patients were homozygous for the FTO obesity SNP variant, 13% were homozygous for the INSIG2 obesity SNP variant, and 3.4% were homozygous for both. Mean BMIs in the groups homozygous for each of these genes were not significantly different from nonhomozygotes. However, FTO/INSIG2 double homozygotes and homozygote/heterozygote pairs had significantly higher BMIs than the other groups.
Conclusion: Increased BMI in morbid obesity is associated with a combination of FTO and INSIG2 SNPs.