Cancer in Corn Snakes Due to Genetics?

Hi all :] I’m a relatively experienced reptile owner, and am looking to purchase my second corn snake. Currently I do not own reptiles right now, though I’ve owned them in the past and immensely enjoyed the experience. However, the first corn snake I owned was a Sunglow Motley corn. She developed ovarian cancer about four months after I purchased her, which was removed and treated, but unfortunately had spread into her lower intestines, thus rendering her unable to eat and she had to be put down.

I was wondering about the different color morphs, and considering that she was one, if that could have caused the cancer. I know that intense inbreeding is committed in order to develop the different morphs in each snake, which in turn causes genetic defects and the potential for diseases. Is this really as common in corn snakes as it is in other animals? My issue is that while I’d love a color morph corn, I'm skeptical now after my previous corn’s death, as she was an immensely healthy animal, ate, shed, and defecated regularly with absolutely no issues whatsoever until she developed the cancer.

As I said earlier, I’m relatively experienced with the breed, and have no issues with buying from a local pet store. I know what to look for in a healthy specimen so I’m prepared to go searching for one. I just don’t want to re-live another corn dying due to cancer because of inbreeding if I do decide to buy a color morph, as rare as that occurrence might have been.

Thanks in advance for any advice or opinions!

Certainly Corns are as susceptible to cancer as any other animal - I lost an Amel to cancer a few years ago and like yours, he'd never had any ill-health before developing the tumour. However, I've not heard of the incidence being higher in particular morphs or bloodlines. Hopefully someone more experienced will be able to chip in.

Sadly, you cannot guarantee to buy any animal as "cancer-free".

Amel is a very widespread gene, so I would think that it would be among the hardiest of genes.

The normals you find for sale are _probably_ not going to be "just" normal. They are the "plain" by-products of someone's breeding project, not the target morph. So they may or may not be any less inbred than any other cornsnake morph.

Wow- there sure are a lot of articles if you Google "odds of cancer increased by inbreeding!! I'll be reading...

http://jama.ama-assn.org/cgi/content/full/300/2/169-a

Human inbreeding is widespread in developing countries of the tropical and subtropical regions of the Eastern hemisphere and involves ethnically different populations.2 These populations overall have a lower incidence of cancers than Western populations, with the exception of Pakistan, which has a higher incidence of breast and other cancers.3 In their article, Assié et al1 cite a study from Pakistan showing that inbreeding increases the risk of breast cancer. Among citizens of the United Arab Emirates, however, inbreeding seems to decrease the risk of several cancers, including breast cancer.4 Because this opposite result is from a distinct ethnic group, the risk differences may arise from different frequencies in different populations of the low-penetrance, tumor-susceptibility alleles that Assié et al propose as the main mechanism of increased cancer risk.

If LOH at a particular locus is carcinogenic (eg, involving a tumor suppressor allele), human inbreeding will decrease the odds of cancer because it decreases heterozygosity. In the offspring, inbreeding increases the probability of homozygosity of the wild-type allele. Homozygosity of a mutated cancer allele (and a cancerous phenotype) is unlikely because most homozygotes will die prematurely, as suggested by animal experiments for Brca1 5 and by the lack of reports of cancerous human BRCA1 and BRCA2 homozygotes in spite of statistical odds to the contrary. Thus, at least 2 mechanisms that rely on increased homozygosis may be called into play in consanguineous populations to protect against cancer.

(Wikipedia has a nice discussion of zygosity including LOH, loss of heterozygosity, which is of oncogenetic importance).

Thanks for the reply guys. I appreciate it.

"Certainly Corns are as susceptible to cancer as any other animal - I lost an Amel to cancer a few years ago and like yours, he'd never had any ill-health before developing the tumour. However, I've not heard of the incidence being higher in particular morphs or bloodlines. Hopefully someone more experienced will be able to chip in.

Sadly, you cannot guarantee to buy any animal as 'cancer-free.' "

Do you think my chances would be better with a natural corn though? Even though they are the byproduct of the breeding? Because you would think they wouldn't carry (or if they do, it would be in small amounts) any genes that would cause cancer. Either way though, since you say it's a rather rare occurrence, maybe I just need to try my luck again with a morph and see how it goes. It was just a heartbreaking experience that I'd rather not subject myself to; it was hard getting so attached to her and then losing her :[


"(Wikipedia has a nice discussion of zygosity including LOH, loss of heterozygosity, which is of oncogenetic importance)."

Thanks for the link to the article, Nanci. I'll be reading that over :]

Do you think my chances would be better with a natural corn though? Even though they are the byproduct of the breeding? Because you would think they wouldn't carry (or if they do, it would be in small amounts) any genes that would cause cancer. Either way though, since you say it's a rather rare occurrence, maybe I just need to try my luck again with a morph and see how it goes. It was just a heartbreaking experience that I'd rather not subject myself to; it was hard getting so attached to her and then losing her :[

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I know how awful it is to lose a Corn - Joshi was 16 years old when he had cancer, so you can imagine how I felt about him. He'd outlasted two long-term boyfriends!

If there was a significant link between a specific morph and a higher incidence of cancer, I feel sure we would have heard about it by now. Some bloodlines have been running for many generations (although most major breeders will bring in new stock regularly). Unfortunately one of the reasons that people come to a reptile message board is to ask about health problems - you only have to look at the lively discussion of stargazing. If there was a definite link between one morph and cancer, I think Corns have been bred in captivity for it to have sounded an alarm bell if it was truly an issue in the captive Corn population - although it's certainly worth keeping an eye open for it.

Cancer has many triggers or causes of predisposition; genetic inheritance is just one of them. There are also links to diet, environment, particular viruses, exposure to carcinogens and sometimes, just pure bad luck. It really could happen to any snake, animal or human. Even humans haven't figured out how to steer clear of 100% of the known factors (and there are probably many more that we still don't clearly understand).

Ultimately, you ought to buy the snake that you feel the most comfortable with. If buying a particular morph is going to make you worried about another loss to cancer, then you should probably avoid it in order to save yourself 15 years of background concern.

Hey Nanci, you BLASTED me with Science : )