Z‐virus infertility - DimethylSulfate/drooldick GitHub Wiki

[A/N -- this is subject to change; I've been playing around with some of the biochemistry of the viruses, so this could be retconned]

There are pretty much two kinds of cells in humans:

• germline cells and gametes, which are sperm, eggs, and their precursors
• somatic cells, which are literally everything else (neurons, stomach lining, bone marrow, etc)

A common concern in gene therapy is the concept of germline editing, eg, editing the genes in gametes. This is not the same as selecting from normal sperm and eggs to create an embryo with desired traits, nor is it the same as editing an existing embryo. This is referring to editing the precursors of sperm and/or eggs. After germline editing, all future progeny are affected by the change, and any progeny that your own kids might have too.

Humans are diploid, meaning we have two copies of almost every gene, because we have two copies of every^† chromosome. When a somatic cell undergoes mitosis, each of the daughter cells get all pairs of the DNA. When a germline cell undergoes meiosis, however, each of the daughter cells gets only one of each pair of chromosomes. This is how you end up with sperms and eggs each having only half of their parent's DNA.

The Z-virus adds an entire pair of chromosomes to an infected. This not an additional single chromosome, like what happens with trisomies -- it is a brand new additional pair of chromosomes.

When Rumase is administered under medical supervision, germline editing does not occur and infected remain mostly fertile, although there is a notable increase in miscarriage. When someone catches the Z-virus from a bite, it will eventually become present in spermatagonia, meaning that a male will produce sperm with a single extra chromosome. However, the z-virus is not present in oocytes, so a female will not have the extra chromosome. This means that a male zeitgabber and a female zeitgabber will have a chromosomal mismatch,^‡ usually resulting in miscarriage early in pregnancy. However, non-infected sperm and a infected eggs are still a compatible match, as the number of chromosomes will be match.

^†Sex chromosomes are a little bit complicated, but the same principle applies. A Y chromosome is basically a fucked up X chromosome, so they will still "pair" together with regard to mitosis and meiosis.

^‡To be precise, this results in a monosomy. In life, trisomies and monosomies are caused by meiosis fucking up in one or both parents, resulting in the wrong number of chromosomes ending up in the egg/sperm/both. It is well-known that certain trisomies are survivable, most famously Down Syndrome. However, the only monosomy that is compatible with human life is Turner Syndrome (one X chromosome) -- everything else will miscarry.