What I'm made of

There have been several blog references to genetic testing for Friedreich's ataxia.  I was tested at the end of 1998, over winter break during my freshman year of college. 

Fall quarter 1998, go Cardinal!

My test was analyzed at the Genetic Diagnostic Lab at the University of Pennsylvania Med School.  They sent me a sample collection kit and I brought it to my local Kaiser lab to have the blood drawn.  I don't have any problem with other peoples' blood and guts, but I don't much like to see my own.  So tried not to watch as they filled the necessary vials and vials and vials of blood.  Then the nurse put my blood in a baggie and gave it back to me to walk out the door, which felt a little odd.  My DNA went off to Philadelphia, and I went back to California, and the results came in the mail in January.

In some ways, the genetics of FA are simple as Mendel's pea plants from my 8th grade biology class.  The gene for FA is recessive and the child of two carriers has a 25% chance of inheriting the disease.

The genetic marker for FA, and the results of the genetic testing, are a little more complicated.  Our genetic code is written on the double helix of our DNA by triplet combinations of four nucleotides labeled A, T, C, and G.  Only a few repetitions of the nucleotides GAA are found at a specific place in the FA gene of a person who does not have the disease.  However, in a FA patient, this combination of GAA nucleotides is repeated hundreds, or even thousands, of times, making it very difficult for the code on the normal part of the gene to be read and thus limiting the amount of Frataxin protein that can be made by the body.

The FA test results report two numbers that equal the number of GAA repeats on the FA gene. One number is from the allele, or gene, inherited from one parent (Mama T) and the other number is from the allele inherited from the other parent (JPT). A number of GAA triplet repeats greater than ~120 confirms the inheritance of Friedreich's ataxia.  Research is underway now to understand the correlation between some FA symptoms and the number of GAA repeats.
 
My GAA repeat stats:

Allele 1 = 7
Allele 2 = 22

Science says I'm normal!


So I can blame all the weird stuff on my crazy friends!