A 6-month-old boy is brought to your pediatric cardiology clinic for evaluation of a murmur heard by his primary care physician. His mother reports that he is healthy and active, with no shortness of breath or recurrent infections beyond what is typical for other children his age. On physical examination, the boy appears well-nourished and appropriately sized. Auscultation reveals a harsh, holosystolic murmur at the left lower sternal border, with no cyanosis or clubbing. Further family history reveals that the mother’s brother was diagnosed with Holt-Oram syndrome. Which of the following is a characteristic feature of Holt-Oram syndrome?
