Review Question - QID 106984

Given the older age of the mother and the physical characteristics of the infant, the child most likely has Down syndrome (Trisomy 21). This is commonly associated with endocardial cushion (EC) defects.

Down syndrome is the most common chromosomal disorder, as well as the most common cause of congenital mental retardation. Patients present with mitral regurgitation, flattened faces, epicanthal folds, simian palmar crease, shortened fifth digit, macroglossia, and other congenital heart defects (combined ASD and VSD). Down syndrome is commonly associated with EC defects. The EC generates the separation of the atria and the ventricles during cardiac embryological development. Specifically, it creates part of the atrial septum dividing the atria and the ventricular septum dividing the ventricles. The EC also divides the single valve between the developing heart's atria and ventricles to complete the formation of the mitral and tricuspid valves. A defect can arise from any of these areas, producing a variety of AV septal defects.

Figure A demonstrates the palmar simian crease of an infant with Down syndrome.

Incorrect answers:
Answer 2: DiGeorge syndrome is associated aberrant development of the 3rd and 4th pharyngeal pouches.
Answer 3: Friedrich's ataxia is associated with hypertrophic cardiomyopathy.
Answer 4: Marfan syndrome is associated with cystic medial necrosis of the aorta.
Answer 5: Tuberous sclerosis is associated with valvular obstruction due to cardiac rhabdomyomas.