Ties THAT BIND

You may not have heard of foetal-maternal microchimerism, but if you've ever been pregnant, you have probably experienced this phenomenon. It's now exciting scientists and giving solace to some grieving mothers.

- GLYNIS HORNING

Gchimera is an organism that contains at least two different sets of DNA. If the word seems vaguely familiar, it’s because Chimera was the hybrid creature in Greek mythology (part lion, part goat, part fire-breathing dragon) that lives on today mostly in the fantasy role-playing game Dungeons & Dragons. And in the Marvel universe, they’ll tell you, it’s a genetically engineered mutant with the DNA of several other mutants combined to achieve a specific set of powers.

In today’s world of science and biology, microchimerism is equally fantastical. Microchimerism is the phenomenon of the presence of cells of one individual in another genetically different individual. It’s what happens in pregnancy when cells pass between the mother and the foetus through the placenta from about the fourth week after fertilisation, in what is called ‘transplacental bi-directional cell trafficking’ – and the effects are only now becoming known.

It is estimated that some of the mother’s cells and DNA pass into the foetus in about 30% of pregnancies, IFLScience reports. In a new study of South African babies born to women living with HIV, superior BCG vaccine responses in babies from these mothers were identified due to maternal cells in the newborn infant (