Genotype data not consistent with clonal transmission of sea turtle fibropapillomatosis or goldfish schwannoma

Recent discoveries of transmissible cancers in multiple bivalve species
suggest that direct transmission of cancer cells within species may be
more common than previously thought, particularly in aquatic environments.
Fibropapillomatosis occurs with high prevalence in green sea turtles
(Chelonia mydas) and the geographic range of disease has increased since
fibropapillomatosis was first reported in this species. Widespread
incidence of schwannomas, benign tumours of Schwann cell origin, reported
in aquarium-bred goldfish (Carassius auratus), suggest an infectious
aetiology. We investigated the hypothesis that cancers in these species
arise by clonal transmission of cancer cells. Through analysis of
polymorphic microsatellite alleles, we demonstrate concordance of host and
tumour genotypes in diseased animals. These results imply that the tumours
examined arose from independent oncogenic transformation of host tissue
and were not clonally transmitted. Further, failure to experimentally
transmit goldfish schwannoma via water exposure or inoculation suggest
that this disease is unlikely to have an infectious aetiology.