Holt-Oram syndrome is a rare disorder characterized by skeletal abnormalities of the upper limbs, typically in conjunction with a cardiac defect. The syndrome is caused by an autosomal dominant mutation in gene TBX5 which can be inherited or the result of a new mutation. The skeletal abnormalities frequently include carpal bone mutations, aplasia or hypoplasia of the radius and ulna, polydactyly, clinodactyly, and hypoplastic phalanges. Notably, the thumb may be absent, underdeveloped, or may develop like a finger. Potential cardiac defects include atrial or ventricular septal defects or cardiac conduction deficits. Depending on the severity of the cardiac defect, this disease can be life-threatening.