Understanding the Importance of Genetic
Testing in Sphynx Catteries

For the last decade, DNA testing has been instrumental in diagnostics and forensic identification. Credibility for DNA testing became clear in the landmark paternity case used to identify the biological father of Anna Nicole Smith’s daughter, Dannielynn in 2006. Millions were watching as the announcement was made that Dannielynn’s father was, unequivocally, Larry Birkhead. Not only was Larry Birkhead then able to claim custody of his beautiful baby daughter, but at the same time was able to lay claim to the late Anna Nicole Smith’s fortune.

As with most new scientific achievements, DNA testing has become more and more available to the general population, and is now being used in forensics and court proceedings that require proof of identification of people involved in crimes. Proper identification has allowed both men and women that have been wrongfully jailed for years to be released due to DNA testing, just as many cases of rape and murder have been solved. One of the biggest advances in medicine is the capability of DNA testing to reveal familial hereditary diseases such as Cystic Fibrosis. People who carry this gene are able to find out the probabilities of their offspring having, or carrying, this dread disease before conception. The possibility that hereditary diseases can be virtually eliminated from the DNA is an exciting prospect to many that otherwise would be reluctant to conceive due to problems with their DNA.
Currently in the news, a moral and ethical debate is continually weighed over the creation of the new designer
baby science where scientists manipulate the DNA after conception to change physical characteristics such as the color of eyes, skin, and hair color.

What Does This Mean for Cat Breeders?
Because we are now able to have DNA testing for our breeding felines for a nominal fee, we can now view a DNA fingerprint of
each cat in our breeding programs (especially when the father is in question), trouble-shoot for carriers of diseases, and blood type,
and understand what and why certain physical characteristics appear in our lines. Hopefully, more DNA options will become available
as laboratories that perform feline DNA testing become more sophisticated. Currently, the profile will give you the following:

Clearly, the advent of this technology is, and will continue to be, extremely valuable for breeders. Knowing what the future may
hold, or at least the probabilities of what the future may hold, is a huge plus to cat breeders around the world. Because there is outcrossing to other breeds of cat in most associations, DNA testing is absolutely necessary to troubleshoot any problems that may occur
with this practice.

Why is it Important to Know About Blood Type and its Relevance in the Sphynx Breed?

Background
Blood type is a classification for some of the proteins (antigens) found in the red blood cells. Blood typing is important because
blood type incompatibility can have serious affects, even death, in newborn kittens, and in the case of blood transfusions.
In felines, there are 3 different blood types: A, B, and the rarer AB. To give some perspective, dogs have 13 different blood types and humans have four.

In felines, type A is dominant over type B. An A blood type cat can be A carrying A or A carrying B. Since the A blood type
cannot be recessive, in B blood type, both alleles must be B (carrying B, and never A). More rarely, there are cats that are AB blood
type and these cases should be treated like blood type A cats when dealing with kittens and blood transfusions. Blood type B cats have naturally occurring anti-A antibodies in their blood. This means that the B blood cells will always destroy the A blood cells. Moreover,
therefore, if a B blood type cat is given a blood transfusion from an A blood type cat, the transfused cells from the A cat will be destroyed by the B, and a potentially fatal reaction will occur. The severity of the reaction varies from cat to cat. Some of the signs in kittens that have died from blood type incompatibility are jaundice, anemia, and bloody urine. Problems with surviving kittens include necrosis of extremities, like the tip of the tail, or the tips of the ears.

In a litter of kittens, antibodies in the blood are in the colostrum of the mother’s milk, so if a newborn blood type A kitten nurses from a blood type B queen during its first few days of life, it may absorb large amounts of anti-A antibodies, causing damage to its type A red blood cells. This is called neonatal isoerythrolysis.

DNA Blood Allele Results
For the very first time in Sphynx, DNA results with both alleles have been compiled by Dr. Melba Ketchum of DNA Diagnostics, Inc. DNA Diagnostics has tested move than several hundred Sphynx and proper sampling techniques were used in these tests. The
results are in the chart below:

One can see that a high number of Sphynx tested are B blood type. There are also quite a large number of Sphynx that are carrying the B blood type, according to this sample. Therefore, it is advisable that all Sphynx in breeding programs have their blood tested.

What if My Cat Has Blood Type B?
Sex of the feline is the most important factor in the discovery of blood type B. Most breeders simply eliminate a type B queen from their breeding program. However, with the advent of DNA testing, there is now another option. The following possibilities should be considered before eliminating a type B cat, especially if it is genetically healthy otherwise. If a type B queen is bred to a type B male, there will be no blood incompatibility issues. However, if a type B queen is bred to a type A male, it will be necessary to hand-feed all kittens for the first seventy-two hours of life to prevent neonatal isoerythrolysis (the amount of time recommended for hand-feeding before it is safe to place the kittens back on the queen varies in preventing neonatal isoerythrolysis). It is important to note that, not only is it very difficult for the breeder to hand-feed kittens this young, but that colostrum will not be available for the kitten unless a colostrum substitute is made available. Colostrum is extremely important for the development of the immune system during the first twenty-four hours of life.

A type B stud can be bred to a type B female or a type A female with no problem for the kittens. In this case, it is wise to breed the type B male to an A/A female (type A carrying A) so that the offspring will be all A blood type but heterozygous, or A/B, the rarer blood type. It follows then, that the next generation probabilities (A/B being bred to a homozygous A/A cat), are that all offspring will still be A blood type, but only 50% will be A/B. Following this reasoning will help a breeder work towards having all blood type A cats in the breeding program.
The charts below demonstrate the optimal solution in the form of a Punnett square when attempting to eliminate blood type B
from a breeding program:

Generation 1: 100% of kittens are blood type A, but all are carrying B blood type.

In Generation 2, it is recommended that the breeder have a DNA test performed on a kitten to be kept for breeding to ensure that the kitten is homozygous A blood type. If the kitten turns out to be heterozygous, then the breeder has the option of repeating the Generation 2 step in hopes of eliminating the recessive B blood type in the next generation.

Because blood type B appears (from this large group of Sphynx population) to be quite high, it would have been, in the past, almost impossible to eliminate it entirely from breeding programs, due to the need for outcrossing to other lines of Sphynx. However, with the availability of DNA testing, each breeder can work towards their population becoming homozygous for blood type A. Additionally, each time a new cat is added for outcrossing, a DNA panel can easily be done in order to keep the guesswork out of the breeding program and, best of all, continue to produce healthy and viable offspring.
The more information we have with regards to the genetics of our breeding cats, the more power we have to maintain successful and healthy breeding programs. Check out www.catgenes.org for your DNA testing. It is a simple non-invasive, fast, and very inexpensive test.

Special thanks to Dr. Melba Ketchum of DNA Diagnostics for her time and assistance in compiling the data for blood type B in this article. Special thanks also to Emily Greene for talking at length with Dr. Ketchum to gain an understanding of the B blood type, and for putting together this information to share with the rest of the Sphynx Community.

Reprint by permission only