A rare case of isolated right atrial enlargement and TBX5 mutation associated with Holt-Oram syndrome.

Holt-Oram syndrome or atriodigital dysplasia is commonly associated with cardiac malformations, most often with defects of the muscular septum. We describe the case of a fetus referred for fetal cardiology evaluation in the setting of right atrial enlargement without tricuspid valve abnormalities with small muscular VSDs, and without other significant cardiac lesions. On serial fetal echocardiograms, isolated right atrial enlargement was persistent as was relative fetal bradycardia without apparent AV block or other signs of abnormal conduction. Limb or other anatomic abnormalities were also not visualized on prenatal scans. A postnatal diagnosis of Holt-Oram Syndrome was made. In the setting of isolated right atrial enlargement, we suggest a comprehensive sonographic search for upper limb abnormalities as well as genetic evaluation.