DiGeorge syndrome involves abnormal development of which pharyngeal arches?

DiGeorge syndrome involves abnormal development of which pharyngeal arches?

• A. 3rd and 4th arches
• B. 1st and 2nd arches
• C. 2nd and 3rd arches
• D. 4th and 6th arches

Answer: (A)

DiGeorge syndrome arises from failure of neural crest cells to populate the third and fourth pharyngeal arches, leading to defective development of their derivatives. The thymus and parathyroid glands originate from these arches (via the third and fourth pouches), so their absence or hypoplasia causes T-cell immunodeficiency and hypocalcemia. The same developmental disturbance also affects the cardiac outflow tract, leading to conotruncal heart defects. A 22q11.2 deletion underlies this pattern. So abnormal development of the third and fourth pharyngeal arches is the hallmark.

DiGeorge syndrome arises from failure of neural crest cells to populate the third and fourth pharyngeal arches, leading to defective development of their derivatives. The thymus and parathyroid glands originate from these arches (via the third and fourth pouches), so their absence or hypoplasia causes T-cell immunodeficiency and hypocalcemia. The same developmental disturbance also affects the cardiac outflow tract, leading to conotruncal heart defects. A 22q11.2 deletion underlies this pattern. So abnormal development of the third and fourth pharyngeal arches is the hallmark.