Working Switches Found in "Junk" DNA, and the Information in the Genome
A gene-editing screen tested a thousand candidate switches in the non-coding DNA once dismissed as junk. About 150 do real work, and many of them control genes tied to Alzheimer's disease.
Published in Nature Neuroscience on December 18, 2025.
- What are these switches?
They are enhancers, short stretches of non-coding DNA that control when and how strongly other genes turn on. Researchers at the University of New South Wales tested about 1,000 candidate enhancers in human brain-support cells and found roughly 150 with a measurable effect on gene activity.
- How did they confirm a sequence does something?
They used gene-editing tools to switch off each candidate one at a time, then measured which genes changed in response. Only sequences that produced a real shift in activity counted as functional, which separates working switches from inert stretches of DNA.
- Why the link to Alzheimer's?
Many of the roughly 150 confirmed switches control genes already tied to Alzheimer's risk. That points to some disease risk operating through non-coding regulatory DNA, not only through the protein-coding genes, and the map is now being used to train models that predict which non-coding sequences do real work.
- What does this say about "junk DNA"?
About 98 percent of the human genome does not code for proteins, and much of it was once written off as junk. This study joins a long series that keeps finding precise regulatory function in that so-called junk.
Pillar in view: functional information in the genome.
The genome keeps reading like code, not clutter
The phrase "junk DNA" began as more than a description. It was a prediction that most of the genome is leftover debris from a long, undirected history. Design thinkers made the opposite prediction, that a genome would turn out to be layered with purpose, with function the rule rather than the exception. Study after study, including this one, has been landing on the side of function.
The reason this matters is information. Dense, organized instructions that specify how a living thing is built and maintained are the signature that design arguments point to, the same way a page of text points to an author rather than to spilled ink. A genome that keeps revealing careful regulatory logic where clutter was expected fits a designed genome far more comfortably than a wasteful one, and it echoes the old conviction that we are, in a real sense, written.
For you formed my inward parts; you knitted me together in my mother's womb. I praise you, for I am fearfully and wonderfully made. (Psalm 139:13, 14)
Sources
- Scientists crack the code on "junk DNA" linked to Alzheimer's Primary
ScienceDaily, on the Nature Neuroscience paper (UNSW; Green, Voineagu et al.) · December 19, 2025 - Junk DNA (topic archive) Commentary
Discovery Institute, Center for Science & Culture