Roux-en-Y gastric bypass surgery (RYGB) accounts for about 80% of bariatric procedures in the US and is usually done laparoscopically. During RYGB, a small part of the proximal stomach is detached from the rest of the stomach, creating a stomach pouch of < 30 mL. Which of the following preexisting conditions has been shown to go into remission in up to 62% of patients 6 yr after RYGB?