Monday, June 25, 2018

Types and Genetics of Long QT #Meg'sLongQTJourney

There are several classifications when it comes to the types of Long QT Syndrome.

First, there are two main forms of Long QT:

1. Inherited
2. Acquired

It's self-explanatory, but the inherited form is genetic related and the acquired form is caused by other reasons, in particular medications that prolong the QT interval.

There are two forms of inherited long QT:

1. Romano Ward Syndrome
2. Jervell and Lange-Nielsen

The main difference is that Romano Ward is the genetic version not associated with deafness, while Jervell and Lange-Neilsen is associated with profound hearing loss/deafness from birth. JLN is still genetic and this is common if you happen to inherit genetic variants from both parents.

One Step Further:

As of this writing, there are, I believe, 15 genetic types of Long QT. It is known that more genetic variants have yet to be discovered. I won't get into all the specifics of the gene variants on here, as it's beyond my expertise.

Some general information:

  • The most common gene variants are Long QT 1, 2, and 3. 
  • Since they are the most common, the most research has been done on these three genes and more is known about these three genes than the other 12. 
  • The others are more rare and some of the latter ones have only recently been discovered. 
  • It is known that Long QT 5 is somewhat similar to type 1. 
  • Long QT 8 is also known as Timothy Syndrome. 
  • Timothy Syndrome is a type of long qt that includes other symptoms such as syndactyly (webbed fingers and/or toes) and developmental delays.
  • There's a 50/50 percent chance of passing the gene to your children.
  • A spontaneous mutation occurs if you are the first person in your family to have a long qt gene.
In Long QT, there are certain triggers/causes for symptoms to occur for each type. However, the triggers can also overlap. I will be going over this in my next post when I will be writing about the symptoms of Long QT.

If you're interested in reading my previous posts in Long QT Journey series, the links are below:
1. The First Seizure
2. Second Seizure
3. The Third Seizure
4. Getting a Diagnosis
5. Long QT Syndrome Explained


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