Lions and Tigers and Endogenic Retroviruses, oh my!

A few months back, I read an article in a scientific journal using statistics from genetic studies to propose a theory that autism in some children--particularly in families with more than one child with autism--may be caused by genetic mutations that enter the germ line (sperm and egg) and that are passed from generation to generation. Thanks to Gentle Reader Ros, Ph.D., for helping me interpret that article. The article suggested that those endogenetic mutations most likely were passed down through the female parent, something that my non-scientific brain wondered about. After all, my wife has five sisters, none of whom have children with autism--and we're talking about women who have between two and four kids.

Yesterday, I read a fascinating article in the New Yorker about the field of paleovirology, or the study of ancient retroviruses. Because retroviruses encode themselves into the DNA of their hosts, they are the only viruses that theoretically could enter the germ line and be passed down intergenerationally. It turns out that numerous retroviruses became endogenic over the years, and that harmless fragments of those retroviruses are in our DNA. It also turns out that a retrovirus may have been responsible for the development of the placenta, which allows mammals to have live births instead of hatching from eggs.

Molecular biologists have been able to piece together some of these ancient retroviruses and reconstruct them (somehow in a socially responsible way that allows them to reproduce only once) for use in research to assist in finding cures for modern retroviral infections. For instance, millions of years ago, other primates became infected with a retrovirus called PtERV, while humans did not become infected. We have a gene called TRIM5a, which produecs a protein that destroys PtERV. Other primates also have TRIM5a, but it works differently in them. In the Rhesus monkey, TRIM5a destroys HIV. Reserachers took the human gene and modified it to work like the monkey gene. What they discovered was that the gene can destroy PtERV or HIV, but never both. So, theoretically, if a medication can be formulated that will work the monkey gene, while not messing up the human one, there may be an effective cure for HIV diseases. It's a well-written article, as any scientific writing must be for me to make heads or tails of it.

The New Yorker article got me thinking about the article I read earlier about autism and its possible endogenetic causes. Could it be that there are dormant genetic mutations carried by both the female and the male of the species, that, when combined after X number of generations of mutation, create a sort of genetic perfect storm? I have no idea. This mad scientist stuff sure is interesting.

ETA--Senator Clinton is pledging to spend $700 million annually towards autism research and suppot services if she is elected president. I'm not endorsing; I'm just saying. Hopefully the other presidential candidates will make similar commitments.