ETV5 / TRA2B contacts · 310 nt · 2026

HAR1984

What it is

HAR1984 is the cleanest current example that a HAR can change architecture, not just volume. Put the human stretch into a chimpanzee cortical organoid and neurogenesis rises. Put the chimpanzee stretch into a human organoid and it falls. Loops to ETV5 and TRA2B move with the letters.

Why it matters

Species-specific 3D architecture → neurogenesis.

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.

• 06 · P

  Population spread

  Once a change is useful, it spreads. Many HAR variants rose quickly in ancestral humans and are now nearly fixed across living populations.

Mosti et al. Cell Stem Cell 2026