October 22, 2004
A: FROM MENTOR LESLIE WAITE IN CA
Ah! Great question Janis!
Fixing DNA damage due to sun exposure requires DNA recombination, and
I worked on DNA recombination for my Ph.D. thesis, so this is a
subject that is near and dear to my heart.
Now you may not realize that a good scientist never says never, but
as close as they get is "highly unlikely". Therefore I will say that
it is EXTREMELY unlikely that a child born to a mother who had
extensive UV damage to her skin would be more likely to develop
cancer. You may well be asking "why is that, Les?" Well, I will tell
you.

The reason that people who have extensive exposure to UV radiation
get skin cancer is that the UV radiation damages DNA. As you may or
may not know, DNA is the molecular building blocks that makes up
genes, and genes are the "blueprints" for all the proteins your body
makes. Muscles? Encoded in genes. Hair? Encoded in genes. Cell
machinery that tells your cells to stop dividing? Encoded in genes.
Now this last category includes many many proteins, and each of them
is necessary to tell a given cell type (in this case a skin cell)
that it can stop making new copies of itself and just hang out with
the other skin cells. If these growth control proteins get messed up,
then skin cells won't get the message to stop dividing, and they will
keep making more and more of themselves in an out-of-control way.
This is what we call cancer. What makes these growth control proteins
get messed up? Well, if the DNA in the gene that contains the
blueprint for the control protein is damaged, then the protein will
be made incorrectly, or not at all because the cell's protein-making
machinery can't read it correctly. Think of a book with 5 pages in
the middle burned out. Depending on what was on those five pages, you
might be able to figure the book out, or you might get the general
gist of the book but miss a few details, or the book might not make
any sense any more. The same thing happens with DNA damage and the
cell's ability to "read" the damaged gene.

So, why wouldn't a woman with messed up DNA in her skin have babies
with equally messed up DNA? Because the DNA she passes on to her baby
comes from one of her eggs, not her skin. No matter how badly a woman
might damage her skin with sun or tanning bed exposure, that damage
would be limited to her skin; her eggs would be fine. So her babies
will be normal. Except for the fact that they have a Mom with really
leathery skin....:)