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Holt-Oram syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Conditions

Holt-Oram syndrome

Holt-Oram syndrome is a genetic condition characterized by skeletal abnormalities of the hands and arms combined with heart defects.

Overview

Holt-Oram syndrome affects the development of the upper limbs and the heart. Skeletal abnormalities can affect one or both arms; if both are affected, the left side is typically more severely impacted than the right. About 75 percent of affected individuals have heart (cardiac) problems, which can be life-threatening.

Symptoms

  • Skeletal Abnormalities: Abnormally developed wrist (carpal) bones, partial or complete absence of forearm bones, underdeveloped upper arm bones, and abnormalities of the collar bone or shoulder blades.
  • Heart Defects: Holes in the wall (septum) separating the heart chambers, known as atrial septal defect (ASD) or ventricular septal defect (VSD).
  • Cardiac Conduction Disease: Abnormalities in the heart's electrical system, which can lead to a slower-than-normal heart rate (bradycardia) or rapid, uncoordinated contractions (fibrillation).

Causes

Mutations in the TBX5 gene cause Holt-Oram syndrome. This gene provides instructions for a protein that plays a critical role in the development of the heart and upper limbs before birth, specifically in the process of cardiac septation and the regulation of bone development in the arms and hands.

Inheritance

This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder.

Frequently Asked Questions

Diagnosis often begins with a routine newborn heart screening that detects a murmur or structural defect such as an atrial septal defect. Because skeletal changes can be subtle in infancy, clinicians may order X-rays of the wrists and hands to check for missing or malformed carpal bones. Genetic testing for mutations in the TBX5 gene is the definitive diagnostic tool, especially if the physical signs are mild or if there is a family history of the condition.
Most children with mild skeletal and cardiac involvement can participate in age-appropriate physical activities, but this depends heavily on the severity of the heart defect and conduction issues. Activities that place extreme stress on the upper limbs or involve high-impact contact may be restricted if the arm bones are fragile or underdeveloped. More importantly, competitive or strenuous endurance sports may be discouraged if the patient has significant arrhythmias or heart failure, as these can trigger dangerous heart rhythms. Clearance from a cardiologist is required before starting any new exercise regimen.
Yes, incomplete penetrance and variable expressivity mean that some individuals with the mutation may have very mild symptoms, such as a small heart defect or minor hand differences that go unnoticed. This makes genetic counseling complex, as a parent might appear healthy but still carry the risk. If a parent is confirmed to have the mutation, there is a 50 percent chance of passing it to each child. Prenatal or preimplantation genetic testing can be offered to families who wish to know the status of the fetus or embryo before birth.
Patients should seek immediate emergency care if they experience sudden dizziness, fainting (syncope), severe shortness of breath, or a racing or irregular heartbeat. These symptoms can indicate the development of atrial fibrillation or high-grade atrioventricular block, which are common complications of the cardiac conduction defects associated with this syndrome. Regular monitoring of heart rhythm is essential to catch these changes before they become life-threatening.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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