DiGeorge syndrome (22q11.2 deletion) results in which combination of immunological defects?

• A Absent B cells with normal T cells — X-linked agammaglobulinemia pattern
• B T cell deficiency due to thymic aplasia, with normal B cell numbers but impaired T-dependent antibody responses ✓
• C Combined severe T and B cell deficiency with absent NK cells — SCID pattern
• D Normal lymphocyte counts with defective complement C3, causing recurrent encapsulated bacterial infections

Explanation

DiGeorge syndrome is caused by failure of development of the 3rd and 4th pharyngeal pouches (thymus, parathyroid), resulting in thymic aplasia and T-cell deficiency. B cell numbers are normal, but T-cell help is absent, causing impaired T-dependent (thymus-dependent) antibody responses. Patients also have hypocalcemia (absent parathyroids) and conotruncal cardiac defects.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.