G551D is a specific mutation in the CFTR gene, which is responsible for producing a protein that helps regulate salt and water movement in and out of cells. This mutation is associated with cystic fibrosis, a genetic disorder that affects the lungs and digestive system, leading to thick mucus buildup and various health complications. Individuals with the G551D mutation may experience milder symptoms compared to other mutations. Treatments often include medications like ivacaftor, which can help improve the function of the defective CFTR protein, enhancing the quality of life for those affected by this mutation.