Islands of euchromatin-like sequence and expressed polymorphic sequences within the short arm of human chromosome 21

Genome Res. 2007 Nov;17(11):1690-6. doi: 10.1101/gr.6675307. Epub 2007 Sep 25.


The goals of the human genome project did not include sequencing of the heterochromatic regions. We describe here an initial sequence of 1.1 Mb of the short arm of human chromosome 21 (HSA21p), estimated to be 10% of 21p. This region contains extensive euchromatic-like sequence and includes on average one transcript every 100 kb. These transcripts show multiple inter- and intrachromosomal copies, and extensive copy number and sequence variability. The sequencing of the "heterochromatic" regions of the human genome is likely to reveal many additional functional elements and provide important evolutionary information.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosomes, Human, Pair 21*
  • Contig Mapping
  • Euchromatin / genetics*
  • Genome, Human
  • Humans
  • In Situ Hybridization, Fluorescence
  • Polymorphism, Genetic*


  • Euchromatin