Devil facial tumour disease

Devil facial tumour disease (DFTD) is an aggressive non-viral transmissible parasitic cancer among Tasmanian devils.

In the subsequent decade the disease ravaged Tasmania's wild devils, with estimates of decline ranging from 20% to as much as 50% of the devil population, across over 65% of the state. Affected high-density populations suffer up to 100% mortality in 12–18 months. The disease has mainly been concentrated in Tasmania's eastern half. Visible signs of DFTD begin with lesions and lumps around the mouth. These develop into cancerous tumours that may spread from the face to the entire body. Devils usually die within six months from organ failure, secondary infection, or metabolic starvation as the tumours interfere with feeding. DFTD affects males and females equally. At present the population has dwindled by 99.9% since 1996. As of 2010, 80% of population is infected. Only point .1% is not effected

The most plausible route of transmission is through biting, particularly when canine teeth come into direct contact with the diseased cells. Other modes of transmission include the ingesting of an infected carcass and the sharing of food, both of which involve an allogeneic transfer of cells between unrelated individuals.

Six females have been found with a partial immunity. Breeding in captivity has begun in an attempt to save the population.

Tasmanian devil cells have 14 chromosomes, while the oldest-known strain of the tumour cell contains thirteen chromosomes, nine of which are recognizable and four of which are mutated “marker” chromosomes. More recently evolved strains have an additional mutant marker chromosome, for a total of fourteen chromosomes. Researchers identified the cancer as a neuroendocrine tumour, and found identical chromosomal rearrangements in all the cancer cells. The karyotype anomalies of DFTD cells are similar to those of cancer cells from canine transmissible venereal tumour (CTVT), a cancer of dogs that is transmitted by physical contact. Among the different alterations present in the tumour genome can be found several single base mutations or shorts insertions and deletions (indels) like deletions in the chromosomes 1, 2 and 3, as well as trisomy in 5p. Some of the mutated or deleted genes in DFTD are RET, FANCD2, MAST3 and BTNL9-like gene.

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