In molecular biology, Human Accelerated Region 1 (Highly Accelerated Region 1, HAR1) is a segment of the human genome found on the long arm of chromosome 20.

It is located within a pair of overlapping long non-coding RNA genes, HAR1A (HAR1F) and HAR1B (HAR1R).

[1][2][3] HAR1A was identified in August 2006 when human accelerated regions (HARs) were first investigated.

One particularly altered region, HAR1, was found in a stretch of genome with no known protein-coding RNA sequences.

[4] Further work on the secondary structure of HAR1A has suggested that the human form adopts a different fold to that of other mammals exemplified by the chimpanzee sequence.