: why does blood transfer not change someone’s DNA?
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1. How would it change your DNA?
2. Red blood cells don’t have DNA, or even a nucleus. They chucked it out to stuff as much hemoglobin (and therefore oxygen) inside as possible.
There is virtually none there to begin with. Only the white blood cells have a nucleus, so they are the only cells that carry any of the donor’s DNA. Red blood cells and platelets lose their nucleus during production in the bone marrow. Donated blood is spun in a centrifuge to separate it into plasma, platelets, red cells and white cells and only the first three are used for transfusions. If whole blood is used in an emergency transfusion, it causes a fever called ‘febrile non-haemolytic transfusion reaction’, as the recipient’s own white cells destroy the foreign DNA.
sciencefocus.com/the-human-body/what-happens-to-the-donors-dna-in-a-blood-transfusion/
Red blood “cells” are not fully alive and don’t have a nucleus or DNA. Other cells in your blood such as white blood cells have DNA, which is how they can get DNA from blood samples.
Your blood doesn’t last all that long. The average red blood cell lasts about 2 weeks. When you get a transfusion, those new blood cells will be gone from your body within two weeks. Blood doesn’t self replicate, it is manufactured in your bone marrow. So any transfusion you get will eventually be replaced by your own blood cells.
Beyond what others have commented, blood cells (white blood cells included) don’t actually undergo mitosis in the blood stream and make other blood cells. They all die within a few weeks.
That said, since blood is created in the bone marrow, if you have leukemia and got a bone marrow transplant then those white blood cells this new bone marrow produces *would* contain the donor DNA. It still wouldn’t change your DNA, but your blood would be carrying foreign DNA. If you then committed a crime, if you left blood then it might match the donor, but if you left hair or skin, it’d match you.
1. DNA is a feature of nearly every single cell of your body. Nucleus of every single cell has the exact copy of your genome within it, it’s just an inherit part of the cell that the entire cell is build around, so inserting a bunch of cells from a different body won’t suddenly shift the DNA in other completely unrelated tissues.
2. Neither can they overtake the body by numbers, cells in normal circumstances are specialized and they don’t shift between different tissues. Blood is a tissue too, and one that doesn’t even replicate – it’s created in bone marrow and after entering the bloodstream it’s already destined to die.
3.Also, blood doesn’t have much of DNA to begin with. Red blood cells are technically dead, they lack the nucleus and any metabolism that comes with it, same for platelets. Only white blood cells have any DNA in them, but majority of them dies in a short time after the transfer or is killed by your body’s white blood cells.
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