An unusual cardiac defect in a patient with clinical features overlapping between cardiofaciocutaneous and Noonan syndromes.

It is important to recognize the possibility of a syndromic etiology of cardiac defects when dysmorphic features and other congenital defects are present. We report a patient who presented with atrial fibrillation and was found to have an abnormal mitral valve, congenital aneurysm of the left atrial appendage, and features consistent with both Cardiofaciocutaneous syndrome and Noonan syndrome. The congenital aneurysm of the left atrial appendage was a previously unreported cardiac presentation for either syndrome. Diagnostic considerations based upon his genotype and phenotype are discussed, along with his unique cardiac presentation and treatment.