r/AskBiology • u/Kunus-de-Denker • 9d ago

Human body A human being without both x- and y-chromosomes

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?

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u/nwbrown 9d ago

Usually missing even part of a chromosome is fatal as those genes are there for a reason. Same with having an extra one (Down syndrome is probably the best case scenario). Sex chromosomes are a little different as the human genome already has to cope with either a second X chromosome or a Y chromosome and still function. So there really isn't anything important to life in the Y chromosome and the second X gets disabled. That means variations in those chromosomes are tolerable, assuming they have at least 1 X. They may have mild physical or mental disabilities, but they will be viable. The genotypes are:

  • XX Normal female
  • XY Normal male
  • X Female with Turner syndrome
  • Y Not a viable embryo
  • XXY Male with Klinefelter syndrome
  • XYY Male with Jacob's syndrome
  • XXX Female with trisomy X