This is like the junkiest of junk, and it turns out to be so critical:
From a PhysOrg article:
To find out what was going on, the researchers began testing the DNA of several families that showed a proclivity for harboring the disease. Some actually had it, while some did not. Comparing the two allowed the team to track down which differences in their genes might be accounting for the presence of the disease. Much to their surprise, they found it lay within gene SLC7A2, which is known to be used by the brain during its development stage. But what was most remarkable was the fact that it was a single letter change, from an A to a G, found inside an intron, which was in turn embedded in a LINE jumping gene, which was itself inside of a dead jumping gene called a SINE element, all three of which were up to now, considered junk genes. The researchers found that if a child got the G marker from just one parent, it was safe. One from each however, meant developing Ravine encephalopathy.
Junk-DNA indeed strikes the Darwinists again.