Every Cell in Your Body Has the Same DNA. Except It Doesn’t. - The New York Times
But scientists are also finding that mosaicism does not automatically equal disease. In fact, it’s the norm.
When a fertilized egg — known as a zygote — starts dividing in the womb, many of its early descendant cells end up with the wrong number of chromosomes. Some are accidentally duplicated, and others lost.
Most of these unbalanced cells divide only slowly or die off altogether, while the normal cells multiply far faster. But a surprising number of embryos survive with some variety in their #chromosomes.