Genome map sheds light on deadly Tasmanian devil tumour

Devil facial tumour disease (DFTD) has already spread to over 70 per cent of the Tasmanian devil population and could threaten the world’s largest carnivorous marsupial with extinction.

Now an international team led by scientists at The Australian National University has completed a genome map of the facial tumour that is decimating devil populations.

The map reveals the tumour to have many unusual features and may help in understanding its origin and how to potentially treat or vaccinate against it.

The team, led by Dr Janine Deakin of the Research School of Biology at ANU, compared the normal Tasmanian devil genome to that of the devils with facial tumours and found that significant fragments of the chromosomes had been jumbled.

The three strains of tumour studied exhibited different rearrangements, but the rearrangements within each strain were found to be surprisingly similar, suggesting a high level of stability in the disease.

The researchers also discovered that the tumour is evolving relatively slowly and has remained virtually unchanged since its emergence in 1996.

“That’s really unusual for cancers because usually, for human cancers, evolution is rapid and the tumour will be completely different between the original tumour and its metastases. In this work we confirmed that the devil tumour is genetically very stable,” said Deakin.

This is compounded by a relative lack of genetic diversity in devil populations, particularly in key regions of the immune system, the Major Histocompatibility Complex, that renders the devils susceptible to the disease.

However, the relative stability of the tumours raises hope that the disease might be treatable in the future.

“In humans, you are usually working with a rapidly evolving cancer and it’s hard to identify the important things because it’s all happening so fast. The Devil is going to be a good model for looking at some human cancers because it is so stable – with everything happening slower we have a better chance of finding those things out,” she said.

The study was published in the journal PLOS Genetics and is freely available online.