Which diseases are commonly associated with congenital thymic aplasia or hypoplasia?

Congenital thymic aplasia or hypoplasia is closely associated with several immunological conditions, primarily DiGeorge syndrome, which is characterized by the absence or underdevelopment of the thymus gland, leading to immune deficiencies. In DiGeorge syndrome, individuals often present with cardiac anomalies, facial dysmorphisms, and hypoparathyroidism, in addition to the thymic hypoplasia, which significantly impairs T-cell development.

Severe combined immunodeficiency (SCID) is another condition linked to thymic aplasia, as it results from various genetic defects that lead to an absence or dysfunction of T cells. Since the thymus is crucial for the maturation of T cells, its underdevelopment or absence directly contributes to the immunodeficiency seen in SCID.

CHARGE syndrome, while primarily a condition resulting from mutations affecting multiple systems, also has an associated risk of thymic hypoplasia. The combination of these three syndromes forms a coherent group where congenital thymic aplasia or hypoplasia is a significant factor, thus making the correct answer to include these diseases together.

In summary, the selection highlights conditions whose pathology directly involves issues of thymic development or function, leading to clinical manifestations of immunodeficiency, which is