Among the many mysteries of human biology is why complex diseases like diabetes, high blood pressure and psychiatric disorders are so difficult to predict and, often, to treat. An equally perplexing puzzle is why one individual gets a disease like cancer or depression, while an identical twin remains perfectly healthy.

Now scientists have discovered a vital clue to unraveling these riddles. The human genome is packed with at least four million gene switches that reside in bits of DNA that once were dismissed as “junk” but that turn out to play critical roles in controlling how cells, organs and other tissues behave. The discovery, considered a major medical and scientific breakthrough, has enormous implications for human health because many complex diseases appear to be caused by tiny changes in hundreds of gene switches.

Full text here:

https://www.nytimes.com/2012/09/...s-crucial-to-health.html

Very interesting! Thanks for sharing

the term "junk" DNA is rather misleading, they are backup copies for
DNA repair. this concept has been entertained by biochemists/molecular biologists for
at least a decade. translocation by retrotransposons may play a role in how they are integrated in newly synthesized DNA; the odd thing is that 8% of the human DNA genome has retroviral origins.

Why is it so odd? I mean, unless that is a unique human trait... A host infected by a retrovirus that has not damaged the host's abilities to reproduce will spread on. In thousands of generations, one would expect to see an accumulation effect. Also, symbiosis is stable.

the retrotransposon functions attributed to said dna make it odd.
solve some of those mysteries, and we would possibly be staring at the
basis behind evolution

It's thought that retrotransposons have some effect on inducing cancer within humans, which makes sense. The gene "jumps" and inserted itself into a proto-oncogene resulting in the production of an oncogene.

http://www.ncbi.nlm.nih.gov/pubmed/20715060

as the abstract mentions, that's one theory of cancer (aside from faulty error-correction proteins). gene-jumping may have other implications as well