Why Sequence Human Chromosome 5?
As a key sequencing center for the Human Genome project, JGI has decoded the sequence of human chromosome 5. The Human Genome Project was begun to determine the complete sequence of the 3 billion bases of the human genome, identify all the genes, and make them accessible for further biological study.
Chromosome 5 is one of the largest human chromosomes, yet it has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of noncoding and syntenic (on the same chromosome) conservation with non-mammalian vertebrates, suggesting they are functionally constrained. It also has many internal duplications. These duplications are very recent evolutionary events and play a likely mechanistic role, since deletions of these regions are the cause of debilitating disorders, including spinal muscular atrophy (SMA).
The US Department of Energy’s interest in chromosome 5 emerged from a series of pilot studies begun at the Lawrence Berkeley National Laboratory focusing on a cluster of interleukin genes located on the long arm of the chromosome (human 5q31). These studies of a million bases of chromosome 5 illustrated how finished human sequence could contribute to gene annotation and how multi-mammal sequence comparisons could lead to the sequence-based identification of noncoding elements that regulate genes. The finished sequence of chromosome 5, and its analysis alone and in comparison to orthologous regions in other vertebrate genomes now provides a chromosome-wide catalog of genes and evolutionarily conserved noncoding sequences. Many of these insights, as well as clues into disease-causing deletions arising from the segmented duplication landscape of chromosome 5, can only now be appreciated with the finished sequence of this chromosome in hand.
Genome Portal site: Homo sapiens chromosome 5
