We are about to embark on a new adventure with the National Institutes of Health – National Cancer Institute, and it seems like providing a little primer about XP/TTD (or at least our understanding so far – we expect to be learning a lot at the NIH!) would be helpful.
First, XP stands for Xeroderma Pigmentosum, TTD stands for Trichothiodystrophy.
And second, don’t look it up! Why? Because the things you read will be frightening and at this moment our girl is decidedly healthy. One thing that doctors expect to find with the advent of whole exome sequencing (WES) is that many disorders have a much wider spectrum than originally thought. The available articles describe the first diagnosed and most severe cases. Those families are heroes because they were the pioneers in seeking answers and participating in research that is now benefiting families like ours.
That said…here’s what we understand…
TitaniumAmy has a problem in her ERCC2 gene. This gene is found in all animals and is one of the basic building blocks of life. Our girl’s particular ERCC2 make up has never been seen before, so we (and the doctors) are still unsure exactly what it all means for her.
The nurse at the NIH told us they call ERCC2 the “Swiss Army Knife” of genes. It does a LOT of things. But basically, when our genes get damaged by things like UV rays (or just living in a world full of damaging toxins), the ERCC2 unwraps the DNA double-helix, snips out (excises) the damaged part, repairs, and then wraps it all back up again. For people with ERCC2 errors, that process doesn’t work as well, and cells become unhealthy or die.
Oddly, though TitaniumAmy is diagnosed with both XP and TTD, in some ways this is a good thing. The doctors are thinking that our girl has some healthy tools in her Swiss Army Knife that are helping to offset the worst parts of both diseases.
So, that’s where we are at. Some might wonder why the doctor supervising the research is at the National Cancer Institute. That’s because the ERCC2 gene is also implicated in some cancers, in particular skin cancer (to which kids with XP are highly prone). So, while we’re participating in research to understand more about TitaniumAmy’s condition, we are also hoping to help doctors learn more about curing other diseases – like cancer. …I guess that makes our girl a hero, too!