Holt-Oram syndrome

Holt-Oram syndrome (HOS), also known as heart-hand syndrome or atriodigital dysplasia, is a rare genetic disorder characterized by upper limb skeletal abnormalities and congenital heart defects. It is caused by mutations in the TBX5 gene located on chromosome 12q24.1, which encodes a transcription factor critical for the development of the heart and upper limbs during embryonic growth. The condition affects both the musculoskeletal and cardiovascular systems, with highly variable expressivity even within the same family. Upper limb abnormalities are present in all affected individuals and range from subtle changes such as a triphalangeal or absent thumb, to more severe malformations including hypoplasia or absence of the radius, and phocomelia. These skeletal anomalies are typically bilateral but often asymmetric, with the left side more severely affected than the right. Congenital heart defects occur in approximately 75% of patients, most commonly ostium secundum atrial septal defects (ASD) and ventricular septal defects (VSD). Cardiac conduction abnormalities, including atrioventricular block and atrial fibrillation, may also occur and can be progressive, sometimes developing even in the absence of structural heart defects. There is no cure for Holt-Oram syndrome, and management is directed at the specific manifestations in each individual. Cardiac defects may require surgical repair or catheter-based intervention, and patients with conduction abnormalities may need pacemaker implantation. Orthopedic interventions, including surgery or prosthetics, may be considered for significant upper limb malformations. Regular cardiac monitoring, including electrocardiography and echocardiography, is recommended throughout life due to the risk of progressive conduction disease. Genetic counseling is important for affected families given the autosomal dominant inheritance pattern and the 50% recurrence risk for offspring of an affected individual.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Holt-Oram syndrome