On bio gender and DNA tests

Question

I think I have a grip on understanding the haploid, and the conceptive moment the bio gender occurs (at conception) caused the the donor sperm's contribution (a haploid of x or y)

What causes the xxy or xyy? Would all the donor's bio children have the same xxy or xyy? Or is this something in the egg that causes this?

Answer 1

If, in the formation of either egg or sperm (meiosis) the sex chromosomes do not separate and each go into a separate cell, but both go into one cell, then an egg or a sperm can contain 2 sex chromosomes. Then, when it unites with an egg or sperm with 1 sex chromosome, it can form a cell with 3 sex chromosomes rather than the 2 it should have, thus resulting in xxy or xxx (trisomy). No, this does not (normally) happen in all the donor's sperm or egg cells so would not affect all children.

If the sex cell which did not receive any sex chromosomes unites with another sex cell, it can cause combinations like X0 (deletion).

There are other combinations which can results as well. Wikipedia has list of combinations.Sex chromosome anomalies

Comments

Okay, so it's a fluke, a chance occurrence, rather than some sort of inheritable "thing" that gets passed along. It sounds totally weird but yeah, flukes do occur. If I recall there's one, the mirror image identical twins, rather than the "usual" identical twins. Or a heart on the other side, or an extra kidney, etc.

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Yes, it is a chance occurence. The chromosomes not segregating equally as they should happens more frequently that we might expect. Some of the anomalies involve the sex chromosomes, others involve the autosomes. It seems that the ones involving the sex chromosomes are not as lethal as those involving the autosomes. I just read that many spontaneous miscarriages occur because of chromosomal anomalies. Not only can the chromosomes not sort properly, but they can break and the pieces not sort properly. There's a lot that can go wrong, but statistically I guess we can still call errors "flukes." Some of the chromosomal number anomalies can be passed to offspring, I just read that a person with Down Syndrome (a trisomy of chromosome 21) has a 35-50% chance of passing the condition to their offspring.