Defect seen in Di George syndrome: September 2009

Ans. B: Cell mediated immunity DiGeorge anomaly (DGA) is a congenital immunodeficiency characterized by abnormal facies; congenital hea defects; hypoparathyroidism with hypocalcemia; cognitive, behavioral, and psychiatric problems; and increased susceptibility to infections. Pathological hallmarks include conotruncal abnormalities and absence or hypoplasia of thymus and parathyroid glands. Thymic hypoplasia or aplasia leading to defective T-cell function (cell mediated immunity) is the hallmark of DiGeorge anomaly Microdeletion of chromosome 22 accounts for more than 90% of cases of DiGeorge anomaly. Deletions of chromosome 22q11.2 are found in the vast majority of patients with DiGeorge anomaly