<prompt> Answer this question truthfullyCould you provide a definition or explanation of Jervell and Lange-Nielsen syndrome?  <response>: <reason> Laboratory findings consistent with the diagnosis of Jervell and Lange-Nielsen syndrome JLNS include: Anemia: patients with Jervell and Lange-Nielsen syndrome JLNS are more prone to develop anemia especially iron deficiency anemia Hypergastrinemia is due to the potassium channels defect Increased gastrin levels due to gastric hyperplasia 