chr14 · 14q13.1 · 249 nt · 2006
HAR21
NPAS3 intron
Anomaly
5.94
Genes
NPAS3
Length
249 nt
What it is
HAR21 lives in an intron of NPAS3. That is a common pattern: the most human-changed DNA often sits inside or beside the genes that wire the brain, acting as local control panels rather than new protein recipes.
Why it matters
Intronic enhancer of the largest HAR-bearing gene.
Operator load
01 · ΔE
Enhancer activity
These stretches of DNA do not code for proteins. They act as volume knobs — turning nearby brain-development genes up or down at the right moment.
03 · T
Three-dimensional rewiring
The genome folds in 3D. Human-specific changes can re-route which switches sit next to which genes, even if the letters look similar in a straight line.
Pollard et al. 2006 · Kamm et al. 2013
Same neighborhood
- HAR2 / NPAS3 — NPAS3 hosts the largest HAR cluster in the genome — a transcription-factor locus that helps build and balance neural circuits.
- HAR202 — A human-accelerated enhancer sitting inside NPAS3. 2025 CRISPR work shows the human letters turn this gene down by changing which proteins can sit on the DNA.