Abstract
<title>Abstract</title> <p>The role that genetic factors versus nongenetic factors play in surgical procedures that aim to assist with weight loss is an ongoing area of discussion. One such post-sleeve gastrectomy complication that may arise in some patients is gastroesophageal reflux disease (GERD). Here, we observed two monozygotic (MZ) female twins who experienced worsening GERD symptoms after sleeve gastrectomy and differing GERD outcomes after Roux-en-Y gastric bypass conversion. We reviewed both patients’ medical, surgical, and social histories, medications, self-assessed severity of GERD symptoms, and objective follow-up studies. One twin had a history of GERD before undergoing sleeve gastrectomy, and both had different surgeons performing their respective surgeries. Both twins’ symptoms initially worsened after sleeve gastrectomy, whereas after Roux-en-Y gastric bypass conversion, one twin experienced decreased GERD severity. This study provides insight into the role genetics may play in the development of GERD after sleeve gastrectomy and Roux-en-Y gastric bypass conversion, with observations suggesting that genetic factors may not be the primary driver of postoperative GERD severity.</p>