A Genetic Variant in the Ghrelin Gene Predicts Who Will Lose the Most Weight After Gastric Bypass Surgery | Research

The takeaway

Patients carrying the rs696217 T allele in the preproghrelin gene lost significantly more weight after gastric bypass (38% vs 31% BMI reduction at 1 year), while a CD40L gene variant predicted poorer outcomes.

38.1% vs 30.5% BMI reduction
Patients carrying the T allele in the preproghrelin gene (rs696217) achieved significantly greater BMI reduction one year after gastric bypass surgery (p<0.001).

What the researchers found

Patients heterozygous for the rs696217 SNP (GT genotype) in the preproghrelin gene achieved 38.1% BMI reduction at 52 weeks post-surgery, compared to 30.5% for GG homozygotes (p<0.001). Carrying the rs1126535 C allele in the CD40L gene was associated with lower BMI reduction at 52 weeks (28.1% vs 33.2%, p=0.049). Variants in the ghrelin receptor (rs490683), another preproghrelin SNP (rs27647), and adiponectin gene (rs2241766) showed no significant association with weight loss outcomes.

Why it matters

Bariatric surgery is a major intervention with variable outcomes, and predicting who will benefit most could improve patient selection and counseling. The ghrelin system is central to appetite regulation, and knowing that a genetic variant in the ghrelin gene predicts better surgical outcomes strengthens the case for personalized medicine in obesity treatment. It also reinforces ghrelin's importance as a therapeutic target.

How the study worked

Prospective cohort study of 100 otherwise healthy obese patients (mean age 45, 65% female, mean BMI 48.0 kg/m²) who underwent Roux-en-Y gastric bypass between 2014-2015. Five SNPs in genes encoding ghrelin, ghrelin receptor, adiponectin, and CD40L were genotyped from circulating lymphomonocyte DNA. Patients were followed at 6, 26, and 52 weeks post-surgery, with 79 completing the 52-week follow-up.

What this study cannot tell us

The sample size of 100 patients is modest, with only 79 completing 52-week follow-up. The CD40L finding (p=0.049) is borderline significant and may not replicate. The study tested only a limited panel of SNPs — other genetic variants may contribute to weight loss outcomes. Single-center design limits generalizability. The mechanism by which rs696217 influences post-surgical weight loss was not investigated. Follow-up was limited to one year.

How to read the evidence

This is a prospective observational cohort study with genetic analysis and 1-year follow-up. While the prospective design and clear endpoint are strengths, the modest sample size, limited SNP panel, and lack of mechanistic investigation are limitations. The primary finding (rs696217) is statistically robust; the CD40L finding is borderline.

When this study was published

Published in 2017, this study contributed to the emerging field of pharmacogenomics in obesity treatment. The concept of using genetic markers to personalize obesity interventions has continued to gain traction.

The bigger picture

As obesity treatment becomes more personalized, genetic profiling could help determine whether patients are better candidates for surgery, GLP-1 medications, or other approaches. This study adds ghrelin gene variants to the growing list of genetic predictors of treatment response. Combined with pharmacogenomic data from GLP-1 agonist studies, a comprehensive genetic profile for obesity treatment selection may eventually emerge.

Questions still open

What is the mechanism by which the rs696217 preproghrelin variant leads to greater weight loss after gastric bypass?
Could this genetic marker also predict response to GLP-1 agonist medications for weight loss?
Would a panel of multiple genetic markers more accurately predict bariatric surgery outcomes than any single SNP?

Common questions

Can genetics predict how much weight you'll lose after bariatric surgery?

This study found that a specific genetic variant in the gene encoding ghrelin (the 'hunger hormone') predicted significantly greater weight loss after gastric bypass — 38% vs 31% BMI reduction at one year. While not yet used in clinical practice, genetic testing could eventually help personalize obesity treatment decisions.

What role does ghrelin play in weight loss after surgery?

Ghrelin is a peptide hormone that stimulates appetite. After gastric bypass, ghrelin levels typically change, which contributes to reduced hunger. Patients with a specific variant in the preproghrelin gene (rs696217 T allele) may have different ghrelin signaling that makes them respond better to the surgery's appetite-reducing effects.

Read the original research

Heterozygosity for the rs696217 SNP in the Preproghrelin Gene Predicts Weight Loss After Bariatric Surgery in Severely Obese Individuals.

Obesity surgery, 27(4), 961-967

View on PubMed ↗Publisher’s paper ↗

Citation

Vitolo, Edoardo; Santini, Eleonora; Seghieri, Marta; Giannini, Livia; Coppedè, Fabio; Rossi, Chiara; Dardano, Angela; Solini, Anna. (2017). Heterozygosity for the rs696217 SNP in the Preproghrelin Gene Predicts Weight Loss After Bariatric Surgery in Severely Obese Individuals.. Obesity surgery, 27(4), 961-967. https://doi.org/10.1007/s11695-016-2387-6