What’s the difference between a mosaic and a chimera?

[A. Hammouda]

Now that we agree on what a chimera is and the possibility of having human chimeras, what’s the difference between a mosaic and a chimera? Are there human mosaics? If yes, are these as rare as chimeras?

[John Brown]

Both mosaic and a chimera have more than one cell line. While a chimera results from fusion of two zygotes, a mosaic is monozygotic. A mosaic results from a somatic mutation leading to a different cell line. It occurs in different species including humans.

Since cancer results from a mutation that gives the cell different genetic constitution, cancer patients can be considered mosaic.

Now to the question “are human mosaic rare?”.  Since all females carry double X chromosomes, only one is active in a cell, all females have two different cell lines and are considered mosaic. This brings natural mosaicism in humans to about 50% of the population.

 

• This reply was modified 2 years, 2 months ago by John Brown.

[Anya Solo]

I once posted here a question about calico cats, and I learnt that a calico cat is a mosaic because the color genes are on the X chromosome.

What makes a calico cat? – Bioinformatics Hub

Thankfully, we do not have such genes. Many of us would be calico girls.

[Author]

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