Hole in the Heart

Caused by a mutation in the TBX5 gene, the Holt-Oram Syndrom, or HOS, affects one in 100,000 people worldwide. The TBX5 gene is ultimately responsible for developing the heart and forming the four chambers of the heart in the womb. Along with regulating the development of the heart before birth, the gene also controls bone growth in the arms and hands.

In affected individuals, the gene is mutated and is thought to disrupt the growth process, giving the patient the classic HOS symptoms. Only one copy of the mutated gene is required to wreak havoc on the fetus. Though HOS is a genetically transmitted disorder, cases of a new mutation of the gene (where there is no history of the disorder in the family) have been presented.

HOS can cause several heart problems. The disorder can lead to Atrial septal defects, or ASD, a heart defect where there is a hole in the muscular wall that separates the left and right upper chambers of the heart, the atria, and Ventricular septal defects, VSD, where there is a hole in the muscular wall that separates the lower left and right chambers of the heart, the ventricles. Problems with heart rate caused by defects in the electrical system that controls the contractions of the heart and holes in the heart can be serous and lead to death if not surgically solved.

The lesser of the two evils, deformities of the bones in the arms and hands may need X-rays to detect. They may also appear in the form of missing thumbs or fingers, short thumbs or thumbs that look like fingers, short or underdeveloped bones in the lower arms, and missing bones in the upper arms.

There is no cure for HOS, but for some patients, surgery to correct holes in the heart is available. The average life expectancy varies because of the wide range of abnormalities. Someone with HOS will never live a normal life.