09/30/2025
This is so incredibly fascinating. Ana Paula Martins, through a blood test, discovered that she has XX chromosomes in every cell of her bodyâŠexcept her blood, where she carries XY chromosomes.
She is female through and through: she presents female, has all functioning biologically female body parts, yet only in her blood she has XY chromosomes.
It was a medical mystery to the geneticists who were investigating her case until Martins revealed a crucial detail - she is a twin.
Now Martins is the first reported case of something called spontaneous chimerism, when a person carries two sets of DNA in their body. It is extremely rare and has only been known to happen in a few animal cases.
But the fact that Martinsâ body tolerated her brothers DNA in her blood her entire life without her immune system attacking it, could help us better understand transplant medicine cases.
The human body is truly incredible!