Genetics

I’ve been thinking a lot about genetics lately. It’s fascinating to me, although I’ve not been able to delve very deeply into the topic. My biology teacher in college loved genetics, but was only able to spend a short time on the subject — yet she was obviously passionate about it.

Sometimes knowledge isn’t all it’s cracked up to be, though. One of the genetic diseases I remembered learning about was cri du chat (which is French for “cat’s cry”, because the children born with this problem — a deletion of information on the 5th chromosome — sound like a cat meowing when they cry). I was also studying French at the time, and it was just one of the things I always remembered. So, several years after that, a woman in our church had a baby, and everything seemed to be going fine… but about six weeks after the baby’s birth, my mom mentioned that the baby had “a funny cry — when he cries he almost sounds like a cat meowing!” Of course I remembered what I had learned in college, and told my mom; then looked up more information on the internet (at 26.6kbps download! — remember those bad old days of dial-up??), and confirmed what I had instantly suspected. As page after page after page said the same things, and I had a little mental check-list of how this baby fit this or that symptom, I felt horrible — almost as if I were giving him the disease, rather than just recognizing it. And then to tell his parents…! Yet that’s what genetic counselors and doctors do every day — tell loving parents that their child has some problem.

My late pastor’s youngest daughter also had a genetic problem — Trisomy 18, which used to be considered 100% fatal, but now it is known that it is not always fatal. One interesting thing about her, though, is that not all of her cells are affected — some of her cells are normal. It’s called mosaicism — like a mosaic made up of all different tiles, some cells are of one type of “tile” while other cells are another type. I’m guessing that what happened is that early in her embryonic development — say, back when she was just 3-4 cells — one or more of her cells lost the extra chromosome and continued their normal development, while the others kept the third 18th chromosome and continued their abnormal development (or perhaps vice versa — I don’t know if it’s possible for normal cells to mutate or divide in such a way that they can develop and pass on a third chromosome, or if it’s only possible for a 3-to-2 division). People with genetic conditions like this who are mosaic tend to have milder symptoms of the problem than those that are affected in every cell.

But other times, genetics can be very cool, because even when it appears that some people are vastly different from each other, we’re really all about the same inside. Like this story demonstrates (below is the picture from the story).

One of these men was a good match for a kidney donation to the other man

One of these men was a good match for a kidney donation to the other man

We might think that these two men had nothing in common, but we’d be wrong. There was so little difference between them, that one man was able to donate a kidney to the other man. Close relatives of the man who needed a kidney were not a good match; but his good friend was. How cool is that!

One Response

  1. I applaud your post on genetics. YOu explained it nicely.

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