A 5-week-old boy is being evaluated for a week-long history of rapid breathing and tiring with feeds. The infant was born at home after an uneventful pregnancy. The mother declined all prenatal testing and ultrasound evaluations. His temperature is 36.7 C (98 F), blood pressure is 76/38 mm Hg, pulse is 124/min, and respirations are 66/min. The patient's cardiovascular examination is notable for a hyperdynamic precordium, a mid-diastolic rumble at the left sternal border, and a 3/6 holosystolic murmur in the apex that radiates to the left axilla. An echocardiogram shows defects in the lower part of the interatrial septum and the interventricular septum. This patient's condition is most likely associated with which of the following genetic conditions?

Question

A 5-week-old boy is being evaluated for a week-long history of rapid breathing and tiring with feeds.  The infant was born at home after an uneventful pregnancy.  The mother declined all prenatal testing and ultrasound evaluations.  His temperature is 36.7 C (98 F), blood pressure is 76/38 mm Hg, pulse is 124/min, and respirations are 66/min.  The patient's cardiovascular examination is notable for a hyperdynamic precordium, a mid-diastolic rumble at the left sternal border, and a 3/6 holosystolic murmur in the apex that radiates to the left axilla.  An echocardiogram shows defects in the lower part of the interatrial septum and the interventricular septum.  This patient's condition is most likely associated with which of the following genetic conditions?

Quizplus · Accepted Answer

11ec160b_38c3_cc62_9249_1fe92dd05be9_MD0001_00 This patient's echocardiogram suggests a complete atrioventricular (AV) canal defect, the most common type of cardiac defect in patients with Down syndrome, an autosomal trisomy. Failure of endocardial cushion fusion results in an ostium primum atrial septal defect; a ventricular septal defect; and a single AV valve. Significant left-to-right shunting and AV valve regurgitation lead to excessive pulmonary blood flow and symptoms of heart failure (eg, tachypnea, poor feeding). Auscultatory findings of AV valve regurgitation (holosystolic, best heard at apex) and increased pulmonary venous return (mid-diastolic rumble) are characteristic. (Choice A) DiGeorge syndrome (22q11.2 deletion) is characterized by thymic aplasia (T cell deficiency) and hypoparathyroidism (hypocalcemia). It is associated with tetralogy of Fallot, truncus arteriosus, and transposition of the great arteries. (Choice C) Marfan syndrome (fibrillin-1 mutation) is associated with cystic medial necrosis of the aorta, which may result in dissecting aortic aneurysms and aortic valve regurgitation. Mitral valve prolapse is also common, but septal defects are not. (Choice D) Mutations in frataxin, a mitochondrial protein important in iron homeostasis and respiratory function, cause Friedreich ataxia. It is characterized by spinocerebellar degeneration and is associated with hypertrophic cardiomyopathy, but not septal defects. (Choice E) Mutations in tuberin and harmartin are seen in tuberous sclerosis. These patients may develop cardiac rhabdomyomas in ventricular walls and AV valves, cutaneous angiofibromas (adenoma sebaceum), central nervous system hamartomas, and renal cysts. However, septal defects are not characteristic. (Choice F) A missing sex chromosome (monosomy) is seen in Turner syndrome (45,X), which is associated with bicuspid aortic valve (most common cardiac lesion) and coarctation of the aorta. Educational objective: A complete atrioventricular (AV) canal defect is comprised of an atrial septal defect, a ventricular septal defect, and a common AV valve. It is the most common congenital cardiac anomaly associated with Down syndrome. __________ References: Genetic syndromes associated with congenital heart disease. (http://www.ncbi.nlm.nih.gov/pubmed/26413101)

A 5-Week-Old Boy Is Being Evaluated for a Week-Long History