New studies of ToF

There is new research into the causes of Tetralogy of Fallot (ToF), focusing on the genetic makeup of ToF hearts.

“Tetralogy” means “four parts,”  and ToF is a combination of four separate problems : a Ventricular Septal Defect (VSD);  Pulmonary Stenosis; an Overriding Aorta; and an extremely muscular Right Ventricle. (Here’s a diagram)

ToF accounts for about 10% of all heart defects, and was the defect that the Blalock-Taussig Shunt was designed to relieve. The B-T Shunt was a palliative measure, meaning that instead of curing the defect, it was meant to relieve it. Even today there is no cure for Tetralogy of Fallot, although it can be surgically repaired.

ToF has always been a puzzling defect because the parents of a Tet child usually have no cardiac issues. Recent research only deepened the mystery as it seems that there is no genetic predisposition, either. ToF seems to “pop up” when it wants to.

Scientists at the Howard Hughes Medical Institute have recently found some clues into the genetic makeup of  the defect. After scouring the DNA of 114 Fallot patients, they have found 11 segments that might lead to the occurrence of Tetralogy of Fallot. They are so small that if you put all these DNA segments together, you can’t see them.

Technically these segments are known as copy number variations. The segments control how much protein is produced by a cell, and the variations can cause too much of one protein, not enough of another – and alter your health forever. So now the work shifts to identifying and controlling individual genes. One has already been found: change that gene, and the risk of having ToF multiplies by nine.

Perhaps this research will one day lead to a pill or injection for expectant mothers  that will stabilize the child’s DNA and prevent the occurance of Tetralogy of Fallot!

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2 Responses to “New studies of ToF”

  1. Ellinger Family Says:

    When we saw the genetics counselor they were looking for a common 22q11 deletion. All of the doctors that saw Nathan said he looked the part even before the test was done. A curious thing happen though, even with the FISH study and the micro aray, they could never find what caused the problem. The genetics doc said that he believed that Nathan had a micro deletion on another chromosome or perhaps it was a protein issue.

    Though I wouldn’t wish having a CHD on any enemy, it has been quite the adventure and learning experience for us. I don’t know that I’d ever want to give this experience up. Meeting new friends, becoming closer to current friends and family, and relying on my spouse more has made our life better and more complete.

    I hope that someone can find a cause for ToF. What a day that would be!

  2. Brianne Ahlborn Says:

    We saw a geneticist also, who looked for 22q11 and checked for DiGeorge in my son when he was born with TOF. Thankfully it was negative, and other than his heart he was perfectly healthy. The cause of his TOF remains a mystery.

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