I've looked at the inheritance figures,
and I have a high chance of having a Tourette's syndrome child...what are my options?
As a genetic counselor in training, I figured I had to go over this question.
The first thing I would suggest to high risk couples is "find
out what the odds really mean".
Here's a test. Without looking at the answer, put these
statements in order from most likely to be affected to least likely to be
affected.
-
There is a 3 in four chance that your child will be normal.
-
One in 2,000 people are affected by this condition.
-
More than 99% of births are normal.
-
There is a 50% chance that you will pass on the disease gene.
-
Half your female children will die.
Done it?
They're all the same condition!
Ok, so that may have been predictable, but it proves my point...statistics can paint very different pictures depending on how they are stated.
So look at the figures again.
Now remember that the child's gene selection is a totally
random process. If there is a 30% chance of an unnafected girl in the first
pregnancy, then your second girl will also have a 30% chance to be unnafected.
So will your third, fourth, fifth, etc.
To demonstrate this, find a coin. Toss it ten times, and note whether it
lands heads or tails. Now probability suggests that you would have gotten
some combo of heads and tails, but maybe you were "lucky" and got all heads or all tails. A coin (assuming you are not using a loaded one) has a 50%
chance of landing heads on every toss So, the chances of getting all
heads is 0.5
10 or approximately 0.0009 (that's 9 in 10000!).
But think about the chances of getting the results you got.
Let us assume you got HtttHHtHtH as your result. Now there is a 0.5 chance
of heads, multiplied by 0.5 chance of tails, multiplied by 0.5 chance of tails,
multiplied by 0.5 chance of tails, multiplied by...hang on.
That works out to 0.5
10 or 0.0009!
So if you think about it, there is every possibility that you could have 13 daughters, all of whom are unnafected!
But, for the same reason that you are likely to get a combination of heads and tails, you should plan for what to do if a child has Tourette's.
It is important to remember that Tourette's syndrome is not fatal, does not hurt (as a rule), and will generally not impair learning or social interaction. It's not nearly as bad as getting a child with cystic fibrosis, for example.
Yet, Tourette's syndrome usually comes with other conditions
that can severely impact on a child's life. And it can be frustrating
sometimes. So you should, when you consider what a Tourette's child will
mean for you, consider the impact as well of severe depression, ADHD, and other
related conditions. You never just get Tourette's syndrome, unfortunately.
There is
always something else with it.
And this would be where the sticking point is. While the majority of
Tourette's syndrome children develop normally and have successful lives, others
really struggle. So much more because many medications for other conditions aggravate Tourette's syndrome. (If you've ever seen a child with
Tourette's on ritalin, you'll know what I'm implying.)
At the moment there is no cure, no gene therapy, and it's
pretty much impossible to test for Tourette's pre-nataly.
So genetic counseling for this condition is easy.
Either:
Risk having a Tourette child
or
Don't have children.
Those are the only choices we have.
sorry.