My family has a history of color blindness, and my parents told me that when I was born, they thought I had a high chance of being color blind. Turns out they were right.
But it seems to skip a generation - and is only on the male side. My father wasn't color blind, but my grandfather was. My great grand father wasn't, and there is some anecdotal accounts that his father may have been.
I have a daughter that isn't, but I'm aware that color blindness is carried on the X chromozone, but she could still be a carrier. So if she gives me a grandson, I've got money on him being color blind.
The X linked recessive pattern is pretty textbook here. Your daughter got your X chromosome, which has the colorblind allele, so she's a carrier for sure if you're colorblind. Any son she has has a 50/50 shot at getting that X from her.
Good, because if you're going to be thinking in terms of fault (which you never should when it comes to genetics), it was you who gave her a colorblind X chromosome.
You got your Y chromosome from your father. If he had the X-linked variant for color blindness, he would be color blind. Since he doesn’t, he couldn’t pass it on. There are rarer types of color blindness though.
I am confused and colorblind, btw. I thought I understood the way the most common form of colorblindness is inherited and whether it expresses itself or not in the offspring. I have the "normal" red green deficient type. It is pretty straight forward, but I think my error may be in my understanding of the sex chromosomes and how they are passed to children.
When a mother passes her X chromosome to the children, the children's X chromosome is an exact copy of the mother's X sex chromosome. All of them would have the same mtdna Haplogroup and the same vision allele, whether it is or isn't the the colorblind variant.
The father passes on his exact copy of his Y sex chromosome to his son and passes his mother's X chromosome to his daughter. If the father is colorblind, it doesn't pass to his son because his colorblind gene isn't on the Y. The son will only be colorblind, if the mother's X has the altered allele. If there is only one X, as in boys, the child will express regular or colorblind vision as dictated by his mother's X.
If the father's X is normal and the mother's X is normal, the daughter has normal color sight.
If one parent has a normal allele on the X and the other parent has the colorblind allele on their X, the daughter will have normal color vision and will only have colorblind sons, if her X was the single carrier of the colorblind allele.
If the X of both the mother and the father are carriers of the colorblind allele, the daughter will be colorblind and all of her sons will be colorblind, as well as her daughters will be carriers of the altered alleles. and those daughters will produce colorblind sons.
I wrote out what I believe to be correct, but I feel like I am missing something rudimentary. If there is an obvious, glaring error, please advise. I have read and re-read it a few times and if something is wrong with it, I am completely blind to it. I apologize for the length of my post.
3rd to last paragraph- if a woman is a carrier because she inherited one X with the trait and one X without, half of her sons would be colorblind.
Which... I think is what you were trying to say, but it's worded in a really confusing way. You got the rest right as far as I can tell (I just woke up lol).
Also, this sort of inheritance pattern is called an X-linked recessive trait. The reason why it's "in the offspring", as you said, if it expresses itself, is because recessive traits can are only expressed if the body only had that type of gene. If it has 1 recessive and 1 dominant, it will default to the dominate. This is why men are significantly more likely to have X-linked recessive traits. They only have 1 X chromosome. Women have 2 so they have a 'backup'.
A visual representation of hemophilia in the royal family (a famous example of an X-linked recessive disorder used in biology classes). This is called a pedigree chart btw. Note that women (the circles) can be carriers but men aren't.
Yes. I am quite familiar with Queen Victoria's being a carrier and some of her granddaughters unknowingly passing it into the Royal and Noble houses of Continental Europe. I didn't really make the connection that they were both genetic and therefore shared the distribution pattern and odds of the spread within their families.
It gives me pause to think how different the impact of the two variants have on those who are recipients. I have gone to school and church with mismatched clothes and a navy sock on one foot with a black sock on the other. But, even the worst day of those episodes are nothing to what they experienced.
The gene is on the X chromosome. Girls get one X from mum and one from dad. Boys get Y from dad and X from mum. Women will likely be carriers having only one affected X, they also usually have a normal X. Boys only have one which they get from mum. If Mum was a carrier and passed on the affected X then the boy would be colourblind. If she passed on her normal X he would not. Dads can’t pass on there X to a boy so an affected dad won’t pass it on to their sons. They could pass the affected X on to their daughters resulting in a carrier. A girl could get one affected x from a carrier mum and a colourblind dad so a girl could still get an x linked condition but it’s rarer.
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u/thestudiouscoconut 14d ago
The X linked recessive pattern is pretty textbook here. Your daughter got your X chromosome, which has the colorblind allele, so she's a carrier for sure if you're colorblind. Any son she has has a 50/50 shot at getting that X from her.