Combined immunodeficiency is a rare genetic disorder that affects the immune system, making it difficult for the body to fight off infections. Individuals with this condition have both T-cell and B-cell deficiencies, which are crucial for a healthy immune response. This can lead to severe and recurrent infections, often starting in infancy. The condition can be caused by various genetic mutations, and its severity can vary widely among affected individuals. Treatment options may include bone marrow transplantation, gene therapy, or immunoglobulin replacement therapy to help manage symptoms and improve immune function. Early diagnosis and intervention are essential for better outcomes.