A 3-hour-old girl is evaluated in the neonatal intensive care unit for cyanosis. She was born at 38 weeks gestation by cesarean delivery for nonreassuring fetal heart tones. The mother is a 28-year-old primigravida who had an uncomplicated pregnancy. Apgar scores were 8 at both 1 and 5 minutes. The infant was initially rooming-in with her mother but was moved to the nursery shortly after delivery due to a dusky appearance. Pulse oximetry of the right hand and leg shows 72% on room air. The patient remains hypoxic after 10 minutes of breathing 100% oxygen delivered by hood. On examination, she is cyanotic and tremulous. She has low-set ears, micrognathia, and a cleft palate. Chest x-ray reveals an absent thymus. Echocardiography shows truncus arteriosus. Given the presumed diagnosis, this patient most likely has which of the following conditions?

Question

A 3-hour-old girl is evaluated in the neonatal intensive care unit for cyanosis.  She was born at 38 weeks gestation by cesarean delivery for nonreassuring fetal heart tones.  The mother is a 28-year-old primigravida who had an uncomplicated pregnancy.  Apgar scores were 8 at both 1 and 5 minutes.  The infant was initially rooming-in with her mother but was moved to the nursery shortly after delivery due to a dusky appearance.  Pulse oximetry of the right hand and leg shows 72% on room air.  The patient remains hypoxic after 10 minutes of breathing 100% oxygen delivered by hood.  On examination, she is cyanotic and tremulous.  She has low-set ears, micrognathia, and a cleft palate.  Chest x-ray reveals an absent thymus.  Echocardiography shows truncus arteriosus.  Given the presumed diagnosis, this patient most likely has which of the following conditions?

Quizplus · Accepted Answer

11ec25c8_d630_776d_bc81_75aa5c03d7d3_MD0003_00 DiGeorge syndrome (DGS), or velocardiofacial syndrome, is a disorder caused by a chromosome 22q11.2 microdeletion resulting in abnormal development of the pharyngeal pouch system and subsequent abnormalities of the face, neck, and mediastinum. The clinical presentation varies but includes the triad of conotruncal anomalies, hypocalcemia, and thymic hypoplasia. Cleft palate and facial dysmorphisms (eg, low-set ears) may also be present, as in this patient. thymic hypoplasia Once DGS is suspected, echocardiography and serum calcium levels should be obtained. Truncus arteriosus is one of the conotruncal anomalies strongly associated with DGS and typically presents with cyanosis and hypoxemia refractory to oxygen administration; other common conditions include tetralogy of Fallot and interrupted aortic arch. Hypocalcemia results from hypoplasia of the parathyroid glands and is likely present in this neonate with tremulousness. Neonates are at high risk for life-threatening hypocalcemic tetany, seizures, and arrhythmias. Truncus arteriosus Depending on the degree of thymic hypoplasia, patients can have T-cell lymphopenia and increased risk of viral and fungal infections. Humoral immunodeficiency can also result from defective T-cell help in B-cell activation for antibody production, increasing susceptibility to sinopulmonary bacterial infections as well. (Choices A and G) DGS is associated with lymphopenia and rarely thrombocytopenia. However, red blood cell and neutrophil concentrations in infants with DGS are unaffected. (Choice B) Congenital heart disease (eg, atrial septal defect, ventricular septal defect), low-set ears, and duodenal atresia can be seen in Down syndrome. Thymic aplasia is not associated with Down syndrome, and DGS is not associated with intestinal malformations. (Choice C) Congenital heart defects (eg, coarctation of the aorta) and horseshoe kidney are associated with Turner syndrome; severe coarctation may present with differential cyanosis (ie, higher preductal than postductal saturation), which is not seen in this patient. In addition, these patients typically have wide-spaced nipples and a short, webbed neck. Genitourinary anomalies are not a feature of DGS. (Choice E) Hypoglycemia is often seen in preterm infants or infants of diabetic mothers. Patients with DGS do not have problems with glycemic control. (Choice F) Inadequate folic acid intake or administration of folic acid antagonists (eg, phenytoin, methotrexate) during pregnancy increases the risk of neural tube defects, which are not associated with DGS. Educational objective: Newborns with DiGeorge syndrome (22q11.2 microdeletion syndrome) classically have conotruncal cardiac defects (eg, transposition of the great arteries, truncus arteriosus) and an absent thymus. Patients are at risk for potentially life-threatening hypocalcemia due to parathyroid hypoplasia. References: 22q11 deletion syndrome: current perspective. (http://www.ncbi.nlm.nih.gov/pubmed/26056486)

A 3-Hour-Old Girl Is Evaluated in the Neonatal Intensive Care