A newborn child is brought to pediatrics emergency by her mother for evaluation of repeated seizure and bluish discoloration of child. Physical examination- revealed the characteristic facial abnormalities as depicted below: Chest x ray was done which revealed the following finding: Which is the anatomical structure is affected in the above clinical scenario?

The frontal chest radiograph: shows a moderately enlarged hea with an egg-on-side configuration and increased pulmonary vascularity. The superior mediastinum is narrow because of thymic hypoplasia. Note is made of the anterior upper mediastinum is empty in lateral view The child characteristic facies with x ray findings s/o DiGeorge syndrome. Loss of thymic tissue compromises the immune system, leading to recurrent infections. Damage to neural crest cells is the most likely eitiology of the sequence because these cells contribute to development of all of these structures, including the stroma of the thymus. 22q11 deletion syndrome These children have facial defects thymic hypoplasia parathyroid dysfunction cardiac abnormalities involving the outflow tract, like persistent truncus aeriosus and tetralogy of Fallot. Craniofacial malformations are often associated. Many of the infants also have seizures clue to hypocalcemia caused by abnormal development of the parathyroid glands. Later in life, they more likely to have mental illness-- schizophrenia and depression. origin of the defects is due to defect of NCC that contribute to many of the affected structures. Endoderm cells from the pouches make the thymus and parathyroid cells and neural crest derived mesenchyme makes the connective tissue. Without this mesenchyme, the epithelial -- mesenchymal interaction occurs which is impoant for differentiation of the glands does not occur.