Wednesday, November 16, 2011

Fragile X testing

The results of the Fragile X test were supposed to be in after 2 weeks, so I called to find out if they were back. They told me that the test they had done here at Duke was inconclusive, and they needed to send the sample out to the Mayo Clinic to do a different test. So it will be another 2 weeks before we get the results back.

The test they did here was the PCR. It looks for the normal copy number of repeats, which is around 30. (Fragile X is caused by having too many repeats in this region: around 30 would be normal, above 200 would be Fragile X) Since Sweets is a girl, and girls have two X chromosomes, they are looking for two bands on the PCR in the normal range. So they might see a 28 and a 30 on a normal girl. But on Sweets they only saw one band.

That doesn't necessarily mean she has Fragile X. She could just have the same number of copies on both chromosomes. If both of her chromosomes had 30 repeats, then they would just see one band at 30 - they can't separate the chromosomes. They can't tell from this test if they are seeing one chromosome's 30 or two chromosome's 30's. Two chromosomes with 30 repeats would still be normal.

If she has Fragile X, then it would only show one 30, so that is still a possibility. In that case, she might have one 30 and one 400, but the 400 is too big to show up on this test apparently. They can only see the repeats in the normal range. So, they have to do another test on her sample that can also see the big repeats, called a Southern Blot. The Southern Blot is a radioactive assay, and not a lot of places do them anymore, so that's why the sample had to be sent to Mayo for this test.

It's all the waiting that kills me really. It feels like this whole process is hurry-up-and-wait. Let's test her for this, wait months for the appointment, then wait again for the results, then when they are negative move on to the next thing and repeat. It makes the whole process take a very long time when we have to wait months between appointments. And the more specialized the docs, the longer we have to wait to see them. I remember when I thought the 3 month wait to see the neuro was a long time. Then I thought the 6 month wait to see genetics was a long time. Now it is going to be at least 8 months to see the developmental ped. It just keeps getting worse! I'm so sick of the waiting. I just want to know something!

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