Cystic fibrosis-gastritis-megaloblastic anemia syndrome is a rare genetic disorder that affects the digestive system, lungs, and blood. It is caused by a mutation in the CFTR gene, which is responsible for producing a protein that helps regulate the movement of salt and water in and out of cells. People with this syndrome have cystic fibrosis, a chronic lung disease, as well as gastritis, an inflammation of the stomach lining, and megaloblastic anemia, a type of anemia caused by a deficiency of vitamin B12. Symptoms of this syndrome include difficulty breathing, frequent infections, poor growth, and digestive problems. Treatment typically involves medications, nutritional supplements, and lifestyle changes.