chr7 · 7p23 · 280 nt · 2021

PPP1R17 HARs

What it is

PPP1R17 helps control the cell cycle in the developing cortex. Extra time in the progenitor pool is one of the simplest ways to grow a larger sheet of neurons. A 2021 HAR survey flagged this gene as a rewired primate/human target.

Why it matters

HAR-rewired cortical progenitor target.

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.

• 04 · D

  Copy-number expansion

  Sometimes the switch is duplicated. Extra copies give evolution more material to experiment with — one copy keeps the old job, another can specialize.

Girskis et al. Neuron 2021