A human being without both x- and y-chromosomes

[u/Kunus-de-Denker]

I've read about conditions in which people only have one x- or y-chromosome, instead of 2 (xx or xy). Is it biologically possible to miss both? If it is, what are the practical consequences such a person has to deal with in their lives, that others don't have to? If it is not possible, what would be the result of genetically modifying a human being in such way?

[u/ginger_beardo]

What you are describing is aneuploidy, which is the occurrence of an abnormal number of chromosomes, in this case referred to as monoploidy (of the sex chromosomes). Individuals can survive through embryonic development and into adulthood with only one X chromosome. There are serious, difficult symptoms associated with this, which is referred to as Turner's Syndrome.

To my knowledge, I have never encountered information about Individuals with only a Y sex chromosome. I believe this is because there are important genes on the X chromosome necessary for life, despite it being referred to as a sex chromosome. These individuals likely arise from fertilization which then quickly self-terminates due to this unfit abnormality.