UGT1A1 and gallstones: For example, red blood cell lifespan in people with GS is reported as 30% below undiagnosed controls and this mild haemolysis could cause symptoms of fatigue.44,45 There is also evidence from genetic studies that UGT1A1 deficiency can increase the risk of gallstones, which could increase primary care consultations for abdominal pain.2,42 Establishing whether abdominal pain is a true symptom is important because in the UK the NICE diagnostic guidelines for GS suggest considering alternative diagnoses if symptoms of abdominal pain are present.3