Variability of the Holt-Oram syndrome in Saudi individuals.

We studied three families in which patients with the Holt-Oram syndrome (HOS) had various skeletal abnormalities and congenital heart defects. Two patients had absent thumbs and first metacarpals, hypoplastic radii, and atrial and ventricular septal defects. Patient 2 had pulmonary stenosis, an atrial septal defect, and triphalangeal thumbs. A sister had atrial septal defect and abnormalities of the thumbs; two brothers had abnormalities of the thumbs. The mother had unilateral defect of the thumb with a normal heart. The third patient had tetralogy of Fallot and hypoplastic pulmonary artery. In two families the HOS appeared to be the result of new mutations; in one it was transmitted as an autosomal dominant trait.