What is often the primary specific laboratory finding in DiGeorge syndrome?

In DiGeorge syndrome, the primary specific laboratory finding is absent or reduced T cells. This condition arises due to a deletion on chromosome 22, leading to developmental defects in the thymus gland, which is crucial for the maturation of T lymphocytes (T cells). As a result, individuals with DiGeorge syndrome often exhibit low or absent levels of these critical immune cells, which compromises their ability to mount an effective immune response.

The absence or reduction of T cells is a hallmark characteristic of DiGeorge syndrome and is used diagnostically to help confirm the condition. Patients typically may also show other findings, such as hypoparathyroidism and heart defects, but the immunological aspect—specifically, the impact on T cell production—is central to understanding the syndrome's effects on the immune system.