A neonate develops spastic contractions on the second postpaum day. Laboratory studies show hypocalcemia. MRI studies demonstrate aplasia of the thymus and parathyroid glands. What is the appropriate diagnosis?

DiGeorge syndrome Chromosomal defect (22q11 deletion) that results in developmental anomalies of the branchial (pharyngeal) pouches and organs that develop from these embryonic structures (thymus, parathyroids, and aoic arch). These children present with tetany (caused by hypoparathyroidism) and deficiency of cellular immunity. They also have characteristic facial features ("angry look"). In the absence of a thymus, T-cell maturation is interrupted at the pre-T stage. DiGeorge syndrome has been corrected by transplanting thymic tissue. Diagnosis: DiGeorge syndrome