Because the Bengal males of the first generation are always sterile, a lot of different domestic breeds were used in the creation of the Bengal. The breed that has been used most often, the Egyptian Mau, carries few recessives, but Ocicats, domestic tabbies, Abyssinians, Burmese and probably some other breeds were also used. All of these breeds may carry genes that are unwanted in the Bengal. The genes that inherit as a dominant, like ginger red, dominant white, Abyssinian ticked tabby and white spotting show up as soon as an individual carries them, and can therefore be selected out very easily. Only matings to cats with this fenotype can bring these genes back into the Bengal.
Traits that inherit recessively, however, can be passed on from generation to generation before ever showing up. If cats that carry one or more of these traits are used in breeding, the kittens will often carry the genes, but not show them, which makes selection on recessive differences very hard. Some breeders even want to use animals with aberrant colouring for breeding, reasoning that these colour differences also occur in wild cats. But these different colours appearing in wild cats, is in our opinion not a sound reason to start breeding them in Bengals. Wild 'aberrations' often do not have the same odds for survival as their more usual coloured cousins. Also, differently coloured wild animals always meet the required 'standard' for wild type. A different colour is then no more than a real speciality, the animal still looks wild. Bengals almost never meet all the requirements for a wild looking type. A differently coloured Bengal may then lose its last 'wild ' looking characteristics (eg. facial markings, light belly, rosettes, contrast), in which case it no longer differentiates itself from other domestic breeds or housecats.
Some examples of unwanted genes are described in the following section. Not only different colouring, but also different coattypes and mutations of bone or cartilage are unwanted. All aberrations described inherit recessively, for it is assumed that nobody will purposely breed dominant aberrations into the Bengal. If somebody should try to do this anyway, the results will be immediately visible in the resulting kittens, with one exception: the lethal manx gene that causes taillessness. Manx carriers can have normal tails, in which case hey are called 'risers'. For this reason, Manx outcrosses to British shorthairs are always called Manxes and never British shorthairs.
This gene, that causes a masking of all tabby patterns, was probably contributed by domestic shorthairs, Ocicats, Egyptian Maus or Burmese. Black (or melanistic) Bengals are born quite often and solid black is the best known example of a colour aberration that exists in the wild. A solid black Bengal, especially one with a lot of ghostmarkings, can look a lot like a little black leopard. But a black Oriental shorthair or even a black domestic has the same effect on people. Breeding with solid black Bengals is not advisable. The masking of the tabby pattern makes it impossible to predict the pattern that its offspring will show. Bengal specialities, like tickingfree coat, glitter, contrast, white belly and warm groundcolour can also only be guessed at. Breeding solid black Bengals makes breeding beautiful browntabby Bengals harder in another way: the presence of solid black kittens in a litter will narrow the choice of a good leopard Bengal, especially if one or the other sex is needed. Of all recessives, the solid black Bengal is easiest to defend, because if it has a perfect type and lots of ghostmarking, it can possess a certain wild beauty.
The gene for diluted colours occurs often in Ocicats, Burmese, Abyssinians and domestic shorthairs. A bluetabby Bengal looks like any other bluetabby, because the special characteristics of the Bengal are not visible on a blue cat. The flowing colourful pattern of the marble, the rosettes, the facial markings and the contrast of the warm groundcolour with the white underside disappears. Bluetabby Asian leopard cats seem to exist, but they will undoubtedly look much less impressive than their warmly coloured cousins. If a bluetabby Bengal is used for breeding, the pattern can be seen, but the rest of the disadvantages mentioned for breeding solid black Bengals are just as valid. The Snowbengal adds a completely unique colour to the catworld, but this can hardly be said of a bluetabby Bengal.
The longhair gene occurs in Abyssinians, Ocicats and domestic shorthairs. Longhaired Bengals are not very spectacular, because their pattern is hardly visible through all the hair. The typical headtype almost completely disappears into the ruff of a longhaired cat. Longhaired Bengals can be quite difficult to recognise as kittens. They have somewhat longer hair and they appear to be a little fuzzier than ordinary Bengals. When the kitten coat is replaced, they develope the plumed tail of a longhaired cat, and later still the full ruff and the longhaired knickers. Longhaired Bengals, like solid black Bengals and bluetabby Bengals, should be neutered and not used for breeding purposes.
These Siamese related colours also occur in Burmese, Abyssinians and Ocicats. Although a browntabby Bengal can have chocolate coloured markings, a browntabby Bengal can always be recognised by its black tail tip. A genetically chocolate Bengal would have a chocolate tail tip and chocolate pawpads.
Mutations (rex, sfinx, bobtail)
There is not much known about the occurrence of these mutations in the genepool of the Bengal. The mutations cannot have been introduced to the Bengal from the breeds used in the creation of the Bengal breed. No Bengals have been known to show a short tail, rex coat or nakedness. One may assume, that no Bengal breeder would ever consider crossing their Bengals to any of these breeds. The thought does occur, that people would want to cross a Bengal into one of these breeds, either to get the attractive goldglitter into their lines, or to get some fresh blood. The Bengal is one of the most healthy cat breeds, because of its unique opportunity to get fresh blood by new Asian leopard cat crosses. If such a mating were executed, no harm would be done if the offspring were only used for the breed with the mutation. But the wild look of the Bengal tends to inherit quite strongly, and especially young kittens, in this hypothetical case carrying the mutation, look quite 'Bengal-like'. A layman or a beginning breeder could buy such a kitten as a real Bengal and use it for breeding, thus introducing the mutation and its connected problems (rex: spasticity; bobtail: aberrations of bone and cartilage) into the Bengal. Of course, this situation should be prevented!
An additional disadvantage of breeding with differently coloured Bengals is, that the recessive genes spread through the entire population unknowingly. Apart from having to count on getting differently coloured kittens in almost every litter, the aberrant genes can combine as well. When this happens, the results are horribly easily imagined: solid blue Bengals, lilac tabby Bengals (cinnamon or chocolate derived lilac?), solid black pointed Bengals, longhaired bluetabbypointed Snowbengals.....the number of possible combinations is enormous. The wild typed and wild patterned Bengals will no longer be recognised in these creatures.
By resolute exclusion of differently coloured individuals from breeding, these colours can be very adequately managed. Of course, the management of these colours must not be taken into extremes. For example: if a completely new line carries the gene for solid black, it suffices to only exclude the solidly coloured animals from the breeding program. Excluding all Bengals from this line would harm the breed very much, because all the new genetic material would be lost. This would be a lot worse than having a solid black kitten, that would be neutered and sold as a pet, once in a while. In the case of (possibly) harmful mutations, exclusion for breeding should be much more strict.