B and T lymphocytes play an important role in the body's immune system. These cells are made in the bone marrow and circulate in the blood and lymph tissues. These cells work together to protect the body against foreign organisms, such as bacteria, viruses, and cancer cells.

DiGeorge syndrome, also known as trisomy 22, is a common syndrome that causes congenital heart disease and many other birth defects. Genetic testing for DiGeorge syndrome is a prenatal screening and diagnosis method that can help reduce the symptoms and mortality caused by the syndrome.