Genetic conspiracy theories

I have a theory.
OK, I have more than one theory based mostly on Google searches and PDF medical journal articles. I’m no geneticist, but I know that whatever discovery this exome may reveal, it isn’t going to be good. Part of me uses my research as insulation - preparation - for the bad news I feel is coming, though I know it won’t help.

With 64 days until E-day, I have another self-diagnosis. While Thalassemia is still on my short list, I present to you all the possibility (or probability) of single gene dominant mosaicism.

What is this new demon? Ah, it is possibly the worst one of all.

Mosaicism is when a person, called “a mosaic,” has some affected cells and some “normal” cells. That means the cells within the same person have a different genetic makeup.
This is where it get personal for me: A mosaic germline mutation is carried by an unaffected parent, who is unaffected because the mutation is not in the other cells of the body. Genetic testing using blood or tissue samples from the unaffected parent will be negative for the mutation.
This is significant because it can be passed on and is often seen in parents who have more than one affected child.
Most mosaics don’t know they carry the mutation until they have affected children.
Germline mosaicism is seen in all inheritance patterns, but it is most commonly linked with autosomal dominant and X-linked disorders. If it is an autosomal dominant mutation, the child will be affected with the disorder and will not be a mosaic.

Ready for the kick in the teeth?

YOU CAN’T TEST FOR IT.

That’s right. Remember all those “clean” genetic tests on my medical chart?

Ready for the kick in the gut?

YOU NEVER KNOW HOW BAD IT IS.

I know what waiting for the exome results is essentially waiting for “my percentage.” I am waiting to see if we should take a calculated risk in the conception of another child. Hubby and I have had many discussions about risk. How high is too high of a percentage of recurrence?

But the chance of mosaic autosomal dominant recurrence can’t be calculated because it depends on the proportion of germline cells with the mutation, which can’t be determined through testing.

Some studies say risk can be as low as 6 percent, some say 30 percent, others even more. Some just give up and say it can’t be predicted. One mentioned that a disorder can affect 100 percent of offspring, if inherited just the “right” way.

So there you have it - my 64-days down genetic theory.