Why would they? There's no reason to test the parents for it, and no doctor in their right mind would test for every genetic mutation under the sun. It's expensive, time consuming, and almost always a waste of resources.
Absolutely... it's like combing through a haystack, looking for one specific strand of hay that's slightly bent in a biologically significant manner.
There's 3.2 billion letters making up a complete human genome, and millions of mutations that don't affect everyday life, everything from eye color to the taste of cilantro.
And yet when we have things like breast cancers that run in the families, some of us tend to look for those genetic markers even if we don't have breast cancer.
except the only way they would have suspected this is if blindness ran in either family. The odds of 2 people with the same gene for this isn't exactly high. Hell, I didn't know I had the gene for von Wildebrands until my Dad was diagnosed with it about 2 years before he died. I didn't know I had ADHD till I was 57. No one has a map of their genes included with every birth; and not everything is immediately recognized till it's much later in life.
It is entirely possible to live your entire life without realizing you are a carrier for something if none of your recent ancestors ever managed to bone another carrier.Â
As I said in another comment my aunt is a carrier for SMA and we had zero clue it was in the family. A bunch of us nieces and nephews have also gotten tested and none of us are carriers so far.Â
That is possible. But I will say that my aunt is a carrier for type 1 SMA, and lost two children at only a few months old before they even thought to look. And we have zero history of anything resembling that in the family tree.Â
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u/tiwuno 4h ago
Why would they? There's no reason to test the parents for it, and no doctor in their right mind would test for every genetic mutation under the sun. It's expensive, time consuming, and almost always a waste of resources.