chr17 · 17q21 · 240 nt · 2006

HAR13

What it is

HAR13 sits in a region of the genome that has been copied and rearranged. Extra copies give evolution spare parts. The protein genes in this neighborhood include ones used in neurons; the HAR is about how those parts are deployed.

Why it matters

Copy-number context for an accelerated enhancer.

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.

• 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.

Pollard et al. 2006