Aneupoldies/genetic translocation/chromonosonal abnormalities
1 Replies
RICHMONDTB - January 4

Can you please explain the differences between anueplodies, genetic translocation, and chromonsonal abnormalities.
Also if you would be as kind to explain at what part of the process these could be expected in the ivf cycle.
And do all of these 3 factors implant early miscarriages?
Thank you so much for this wonderful board and input and information.


Dr Smith - January 8

WARNING!!! I'm not a genetist (nor do I play one on TV). I'll give it a shot.

Anueploid: An abnormal number of chromosomes.

Humans have 22 pairs of chromosomes and the sex chomosomes (XX=female; XY=mail - just kidding). Thus, there are 46 chromosomes in total. When things go wrong, as they sometimes do, the egg or sperm ends up with the wrong number of chomosomes to contribute to the embryo. The vast majority of the time, anueploid embryos fail to develop beyond the first trimester. However, in cases where the embryo has 3 pairs of chromosome 21, or even when it has 2 normal chromosome 21's and a piece of another chromosome 21, the result is a Down's Syndrome baby.

Translocation: When a piece of one chromosome moves to a different chromosome.

If all the genetic material is retained when sperm and eggs are made, this is called a balanced translocation. No problem. This is fairly common (1 in 500). However, if some of the genetic material from the chromosome with the translocation is lost when sperm or eggs are made, this is called an ubalanced translocation. This is serious and usually fatal.

Chromosome abnormalities: In addition to the chromosomal abnormalities decribed above, there can be point mutations.

Point mutations can cause a gene to stop working. We have a second copy of each gene on each chromosome just in case this happens, so it may not be fatal (heterozygous mutation). However, if both the genes on both chromosomes are mutated (homozygous mutation), it may be very serious and fatal.

Anueploidies, translocations, and point mutations can all have an impact on embryo and fetal development and miscarriage. Where the impact occurs would depend on the specific abnormality.

Whew! Hope that explains it. If not, I will defer to a genetist.



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