Ian Dunham on Sequencing Chromosome 22
  Ian Dunham     Biography    
Recorded: 16 May 2004

So the chromosome 22 sequencing came out of—there were many groups actually involved in the mapping of the chromosome—our own group at the Sanger Centre, a group with Beverly Emmanuel in Philadelphia is involved, Bruce Roe in Okalahoma was doing sequencing, Professor Shimizu at Keio University in Japan had been doing mapping and sequencing on chromosome 22, and there were a number of other groups [including] A collaborator Jan Dumanski in Stockholm. And all of these different people were working, sometimes on the same areas of the chromosomes, sometimes on different areas.

When we made the decision to go to full scale sequencing of the chromosome what we had to do was to try to organize those groups. So we had separate areas of the chromosome to work on. For instance, the Keio group in Japan worked on the area closest to the centromere, Bruce Roe’s group sequenced the next piece along towards the telemetric [end] and the Sanger Institute sequenced the rest of it. And what we had to do was to make sure that we weren’t sort of overlapping with each other, but that we knew where our boundaries were. That process actually worked really well. We only had a few occasions where we sequenced the same pieces as the other group.

Working at the Sanger Centre, Dunham heads the team, which sequenced human chromosome 22. He is interested in uses of human chromosome 22 as a model system for genomic analysis. Chromosome 22 represents about 1% of the whole genome but is a relatively gene rich chromosome. As such it is a tractable model system for a number of genome-wide studies.

Dunham’s initial work was in comprising physical maps in yeast artificial chromosomes (YACs) to produce an extensive YAC map, which served as the backbone for future production of the DNA sequence.

From 1996-1999 he focused on bringing the sequencing of human chromosome 22 to completion. This was achieved with the publication of the completed sequence and its analysis (Dunham et al. 1999). At the same time the group was responsible for establishing a benchmark level of gene annotation on the sequence. Currently chromosome 22 represents the best-annotated region of the human genome, and provides an excellent model system to develop functional genomic approaches. He was the leader of the consortium of four sequencing groups and numerous collaborators.

His team’s future research interests build on the knowledge of human chromosome 22 as a defined subset of the human genome to develop approaches to studying gene expression and networks at the mRNA and protein level. These include microarray expression analysis, cloning of tagged genes and expression of their proteins, development of phage antibody resources, and study of protein intracellular localization.

Dunham was formerly a Research Fellow and a Postdoctoral Research Fellow at Guys Campus in London.

The BBC interviewed Dunham:

Computer modeling suggests there may be as many as 1,000 genes on chromosome 22, but even this is but a small fraction of the estimated 60,000 to 100,000 genes in our cells.

Human disorders "One down, the others to go," said Ian Dunham, a biochemist at the Sanger Centre in Cambridge, UK, and lead author on the scientific paper in the journal Nature that announces the genetics landmark. "It's a great relief to have it finished."

Mutations to genes along chromosome 22 contribute to heart defects, immune system disorders, cancers, and mental retardation. A gene linked to schizophrenia is also thought to reside somewhere on chromosome 22.