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Holt-Oram syndrome is a rare genetic disorder that affects the development of the upper limbs and heart. Symptoms include skeletal abnormalities and serious heart problems. It is caused by a mutation in the TBX5 gene and can be inherited or result from a new mutation. Treatment focuses on relieving symptoms and improving function. Genetic counseling is recommended for those carrying the mutation.
Holt-Oram syndrome is a rare genetic disorder that causes heart problems and abnormal bone development in the upper limbs. These symptoms can manifest in a myriad of ways ranging from abnormalities that can only be detected via X-rays to a complete absence of forearm bones. Some with Holt-Oram syndrome may have no thumb at all or an elongated finger-like one. Skeletal abnormalities can affect only one or both sides of the body. Most patients also develop serious heart problems, such as a hole in the septum or an abnormal heart rate.
This condition is similar to Duane’s radial ray syndrome, although it is the result of a different genetic mutation. Holt-Oram syndrome is caused by a mutation in the TBX5 gene that affects in utero development of the upper limbs and heart. The gene likely plays a crucial role in the development of a normal four-chambered heart and arm and hand bones. The characteristic mutation of this syndrome interrupts these processes regulated by that gene.
A mutation in the TBX5 gene can cause a myriad of problems for those who develop Holt-Oram syndrome. The carpal bones are almost always affected, although this abnormality can only be revealed by X-rays. The bones of the upper arm may be underdeveloped or completely absent. The thumb may be too short or long enough to resemble a fifth finger. The collarbone and shoulder blades can also be affected by this syndrome.
Two-thirds of these patients also develop some type of heart problem. Such problems are often life-threatening. Septal defects, such as holes in the muscular wall that separates the chambers of the heart, are common. Abnormal heart rates that can be too fast or too slow are also common. In some cases, the heart may be toward the center of the chest instead of to the left, and the veins may be draining blood improperly.
Diagnosing this condition is a process that usually begins when a baby is born, if the arm and hand abnormalities are evident. If not, Holt-Oram syndrome may not be suspected until heart problems occur. X-rays generally reveal skeletal abnormalities, while an EKG can show if heart problems are also present.
There is no cure for Holt-Oram syndrome, so treatment is often focused on relieving symptoms and improving the patient’s function. Heart problems are usually evaluated and treated by a cardiologist. A septal defect can be treated with medication, but surgery is also often recommended. An orthopedic surgeon may be consulted regarding serious skeletal abnormalities.
The mutation that causes Holt-Oram syndrome is rare, affecting about one in 100,000 people. It can be inherited, resulting in only one mutated gene copy per cell. Most patients, however, have no family history of the syndrome because their cases are the result of a new mutation. Those individuals who carry Holt-Oram syndrome may wish to seek genetic counseling before having children, as any biological child may have a 50% chance of inheriting the mutation.
