Genetic Defects Guide | Updated: 2/11/25

[Boopaw]

A GUIDE TO GENETIC FELINE DEFECTS

All image assets provided by @lokisaurus for use on Purrgatory only.

Please know that this is not an all-encompassing guide. Disabilities often exist on a spectrum of how much one can accomplish through a combination of accommodations, existing environments, and avenues to support systems and treatment (if wanted / applicable.) Even though many hours have gone into verifying the information in this guide is as accurate as possible, we can not claim to boil down the entire medical history of a cat (or group of cats) to one or two easy paragraphs. Please keep in mind as you read and feel free to offer feedback where applicable.

Beyond the feline-specific conditions listed below, we do allow cats to have human disabilities and mental illnesses; however, we expect players to conduct their own research and we also expect all disabilities and/or conditions to be played with integrity and respect. These conditions will not be added to this guide, as we do not wish to create a "canon" that lived experiences may deviate from. If you have a suggestion for a condition or disorder that does occur naturally in felines, however, please reach out to the staff team so that we may verify the request and conduct the proper research to add it here.

EAR DEFECTS BUILD DEFECTS COAT DEFECTS SENSE DEFECTS NEUROLOGICAL DEFECTS

• content warning The following slides include clinical discussions on certain disorders, illnesses, and disabilities relating to feline anatomy. Certain genetic conditions may be referred to as "defects", "abnormalities", or "deformities", as this is the terminology used to medically describe the conditions contained in this guide. If you have any concerns regarding the wording and/or information provided here, please do not hesitate to reach out the moderation or admin teams to review.
  
  Reader discretion is advised.

• CURLED EARS " Cu _ "​

  
  Found most prominently in the American Curl breed, the curled ear gene is a dominant trait expressed by the "Cu-" allele. A cat is only required to have one copy of the gene to express it, and this gene can be passed on to further generations with complete dominance. The curled ears gene is not known to be attach to any genetic health conditions, though it is theorized that curled ear cats are prone to more infections - make sure your kitty washes in and behind their ears regularly to stay in tip-top shape!
  

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  FOLDED EARS " Fd _ "​

  
  Found most prominently in the Scottish Fold breed, the curled ear gene is a dominant trait expressed by the "Fd-" allele. A cat is only required to have one copy of the gene to express it, and this gene can be passed on to further generations with complete dominance. The folded ear gene is caused by a type of osteochondrodysplasia which can cause further health issues as the cat ages. While not lethal, cats with folded ears may have certain restrictions to their abilities based on how their conditions are played out.
  
  The gene causing the folded ear trait is a dominant gene which causes intensive skeletal problems if the cat inherits two copies of the gene. For the purposes of semi-realism and player freedom, the genetics team will treat all folded ear designs as having only one copy of this gene, unless otherwise instructed.
  
  

  Osteochondrodysplasia: a developmental abnormality that affects cartilage and bone development throughout the body. This condition causes the ear fold as well as malformed bone structures, and the breed can develop severe painful degenerative joint diseases at an early age.

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  MULTIPLE PINNAE

  
  The four-ear trait affects only the outer ear flaps, or pinnae, and not the inner-ear mechanism. It's thought to be a recessive trait, manifesting itself only when the kitten inherits a rare genetic mutation from both sides of the family. Doesn't really affect anything.

• BOBBED TAILS " Jb _ " or " M _ "​

  
  There are two known mutations that cause cats to have naturally bobbed tails: the mutation seen in Manx cats and their associated lineages (known as "Manx tail"), and the Asiatic bob-tail (seen in breeds like the Japanese Bobtail and the Kurilian Bobtail). For the purposes of semi-realism, the genetics teams will always assume that a cat has inherited the Asiatic bob-tail over the Manx tail, as the Asiatic bob-tail does not come with any unfortunate side-effects for the sake of the bob.
  
  Healthy bob-tails can still jump, climb, and play like any other cats. Bobbed tails breeds are very specifically known for being daring, active, and strong cats, if they do not inherit Manx syndrome associated with the Manx tail mutation. There are a number of factors that lead into a cat maybe inheriting the disorder, and having a copy of the Manx tail genome does not guarantee a diagnosis, but it does mean that a cat can develop Manx syndrome later on. Generally, a cat will begin showing symptoms as early as four months if they are affected.
  
  Homozygous Manx tail ("MM") will be considered lethal. In these cases, we would like to remind all players that roleplaying topics like still-birth and child loss may be extremely triggering to some community members; please take care to write such things as sensitively and respectfully as possible. Please reach out to the moderation or admin teams if you have any questions.
  
  

  Manx Syndrome: a range of conditions seen in the Manx cat and associated lineages, beginning with it's characteristic feature: a shortened tail (or lack thereof). This is a vertebral mutations that affect both the tail and the spinal cord; as such, most common developmental problem seen in Manx cats is spina bifida. Spina bifida is a general term used to describe several conditions where the neural tube which forms the spinal cord fails to close and the arches of the vertebrae (bones of the spine) also fail to form completely. Symptoms include: abnormal "hopping" gait, plantigrade stance (with more of the hind leg on the ground than normal), general incontinence, and lack of sensation in the hind legs. Some cats can be so severely affected that the deformity is fatal.

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  BRACHYCEPHALY

  
  Brachycephalic cats - or flat-faced cats - have shortened muzzles due to a shortened skull structure, which gives them a distinctive "smushed" face appearance. This can lead lead to further abnormalities based on the severity of the muzzle stop, including: extremely narrow nostrils, a longer than normal soft palate, narrow trachea (or, BOAS). Brachycephalic cats may also have protruding (or "peke") eyes, misaligned teeth, and an extremely wrinkled face. They may also be prone to dental disease, exposure keratitis, and bacterial or fungal skin infections.
  
  In Persians, you may see the terms "peke-faced" and "doll-faced" to describe different facial features. "Peke-faced" Persians are bred to have flatter, more extreme features, which increases the risk of more severe health issues from a young age. "Doll-faced" Persians typically have noses that extends outwards, with larger nasal passages, limiting the amount of health issues the cat may suffer from later on in life. Unless otherwise indicated, the genetics team will treat all brachycephalic cats as if they have longer noses and larger nasal passages when calculating possible risks.
  
  

  Brachycephalic Obstructive Airway Syndrome (BOAS): referring to a group of conditions that stem from having a compacted skeleton that can change the shape of the head, face, and throat.

  
  A healthy brachycephalic cat can live a long, happy life so long as they are taken care of. For the purposes of semi-realism, our site does not require that the worst symptoms related to brachycephaly be roleplayed out (based on individual role-player comfort). Please reach out to the moderator or admin team for clarification if needed.
  
  

  CLAWLESS

  This section does not cover declawing. Please see this post for more information regarding onychectomy.
  
  While exceedingly rare, there are two possible reasons why a cat may be born without claws: epitheliogenesis imperfecta and syndactyly.
  
  
  
  A rare congenital defect, epitheliogenesis imperfecta is a skin disorder where the skin has failed develop in areas on the cat. In certain cases, this particular disorder can account for a cat being born without claws. If large parts of the cat's skin have been affected, this disorder is considered lethal, but for the purposes of semi-realism, we will allow cats that are only affected with clawlessness, so long as this defect is played realistically.
  
  
  
  Syndactyly is a genetic condition in which two or more digits on a paw to be fused together, which can cause claws to abnormally grow (or not grow at all). Little to no serious health problems have been reported in conjunction to syndactyly, so players are free to assume that their cat has no side-effects if affected.
  
  Cats without claws are expected to have a more difficult time hunting or climbing, but a warrior's life does not have to be purely about one or two generalized tasks. Please reach out to your leader to see if your cat may be eligible for more accommodating tasks under their reign.
  
  

  CURLED TAILS " rtrt "​

  
  A mutation found exclusively in the American Ringtail breed, the curled tail gene is a recessive trait expressed by "rtrt" for ease of calculation. It is unclear exactly what causes this funny mutation, but it sure is cute and (as a fun bonus) does not seem to be linked to any negative side effects as of writing this guide.
  
  

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  DWARFISM

  
  Made ever-more prevalent due to the popularity of the "Munchkin" breed, feline dwarfism is caused by handful of genetic defects affecting a cat's build, bone structure, joints, and nervous system. There are three main types of dwarfism in cats – osteochondrodysplasia, pituitary dwarfism, and selective dwarfism. As with most diagnoses of this scale, there is a spectrum of severity to consider when discussing feline dwarfism. There are documented individuals that have lived full, happy lives, those that are able to adapt easily to their symptoms with a certain amount of help from their owners. However, there are just as many cats that are severely affected by bone dysplasia, joint pain, arthritis, lordosis, and other spinal and nervous disorders.
  
  Cats with dwarfism are categorized mainly by their disproportionate body types, favoring short or "stumpy" legs and larger heads compared to the rest of their body. They may also have enlarged joints, bow-legged stances, and noticeably shorter or undershot muzzles.
  
  For the purposes of semi-realism, our site does not require that the worst symptoms related to dwarfism be roleplayed out in detail (based on individual role-player comfort), but please be sure to be as sensitive and respectful as possible while approaching subjects such a chronic pain and long-lasting physical disability. It is expected that cats with dwarfism will most likely be unable to carry out certain duties due to. Please reach out to your leader to see if your cat may be eligible for more accommodating tasks under their reign. Please reach out to the moderator or admin team for clarification if needed.
  
  

  POLYDACTYLY

  
  Extra toe beans. No issues here.

• ALBINISM " cc "​

  
  Albinism in cats is very specifically tied to the "color restriction" gene, which typical presents a variation of a pointed cat. However, when a cat receives two copies of the recessive " c " allele, it will present as albino. Albino cats have a complete lack of pigment, making them white with some variation of light eye color (typically blue, pink, or lavender with a red pupil.)
  
  Albino cats may be more susceptible to skin problems (due to their lack of pigmentation), deafness, blindness and/or photosensitivity (due their depigmented eyes). For the purposes of semi-realism, it is not required of any member to role-play out the worst symptoms of albinism (i.e: skin cancer, vestibular disease), but it is expected that some albino cats may have to have certain accommodations allotted to them in order to complete their warrior duties. Please reach out to your leader to see what accommodations would be allowed under their reign.
  
  

  VITILIGO

  A favorite among the genetics team, vitiligo is an inheritable gene that causes cats to progressively gain more and more white spotting as they age. This gene is separate from dominant white and white spotting, and is instead classified as a skin condition. While technically an auto-immune disorder (as the depigmentation is caused by the immune system attacking melanocytes), vitiligo in cats has not been directly linked to any other long-term health defects. It just... makes the kitties extra spotty.
  
  

  SOMATIC MUTATIONS

  An isolated gray or black patch that comes from a mutation affecting tissue cells during fetal development. Most often seen on red or cream cats but the genetics team had allowed isolated patches on other coat colors. May or may not be passed down to future generations but does not count as a type of chimerism or tortoiseshell for the purposes of litter calculation.
  
  

  FEVER COATS

  A temporary lightening of the coat that is present at birth and fades with time (usually between four months to one year of age). This is caused by the dam (or carrying parent) undergoing high levels of stress during the pregnancy. Fever coats are most often silver, but can also be gray, cream, or even white depending on the affected kitten and the base coat. Fever coats do not negatively impact the kitten themselves, though other stressors from pregnancy may lead to other problems or defects (see: cerebellar hypoplasia)
  
  

  HAIRLESSNESS

  There are a variety of genes that would affect a cat's coat to cause hairlessness, all of which can most easily be categorized by breed. Please see the breed categories below for the variations of hairlessness recognized by the genetics team so far:
  
  

  SPHYNX ( hr - ) perhaps the most famous of any hairless cat, the Sphynx owes its birthday suit to a recessive mutation that removes the keratinization function of the hair follicle, causing hair to fall out easily (or barely grow at all.)

  
  

  DEVON REX the Devon Rex shares the same mutation that causes weak hair follicles, however, the Devon Rex retains some function of the protein that allows hairs to be securely rooted. The Devon Rex form of the mutation is considered dominant over the Sphynx mutation, and Devon Rexes may also be a little fuzzier than their more maked counterparts. Because of this minor distinction, a cat cannot be a "Sphynx / Devon Rex" mix, and their breed categorization will depend on which form of the mutation they inherit.

  
  

  LYKOI the lykoi's hairlessness is caused by a form of congenital alopecia, which causes cats to lose hair over the course of their life. It is a natural mutation within domestic shorthair cats, though recessive and therefore relatively uncommon. This gene is not related to the hairlessness gene found in Sphynxes or Donskoys.

  
  

  DONSKOYS the underdog of the hairless breeds, the Donskoy holds the true distinction of having a dominant hairlessness mutation. Donskoys also come in a spectrum of baldness from lightly fuzzy to full short wire coat.

  
  

• DEAFNESS

  There are a few different reasons as to why a cat may not have a full range of hearing ability, however the most common congenital reason is attached to the dominant white gene "W _". Dominant white cats with blue eyes are 80% more likely than the average cat to be mostly to completely deaf. Can also be caused by ear mites, injury, or old age.
  
  

  Congenital Hearing Loss

  Genetic hearing loss in cats is most often due to the W locus (dominant white), with blue-eyed white cats being at the highest risk of congenital deafness; can be diagnosed as early as a couple days to a couple weeks old.

  
  Deaf cats can still live perfectly normal, happy lives despite their disability and are prone to relying more heavily on other senses when their hearing fails. Cats on Purrgatory are also allowed to use their own forms of "kitty sign language" to communicate, if the player so chooses. Incompatible with the Aural ability.
  
  

  BLINDNESS

  There are a variety of reasons why a cat may have congenital blindness and a multitude of ways that such things can occur, including but not limited to: a dam carrying panleukopenia (FPV) while pregnant, kittens inheriting the recessive allele for congenital glaucoma, cataracts, or retinal dysplasia. Rarely, cats be also be born with missing eyes or no eyes at all based on certain genetic makeups.
  
  Blind cats can easily have long, happy lives with some accommodations made for them. There is precedent in both real life and the Warriors book series for cats to not have too much difficulty adapting to an active lifestyle, and are able to be full-duty warriors if the player so choses. Incompatible with the Perspicacity ability.
  
  

  ANOSMIA

  A relatively uncommon condition that affects a cat's ability to smell properly, caused by a developmental abnormality of the olfactory bulb (which allows cats to distinguish and process scent). Cats can also develop a sort of anosmia as a symptom of brachycephaly or respiratory infection (non-hereditary.) Incompatible with the Redolence ability.
  
  

• CEREBELLAR HYPOPLASIA

  Also known as "wobbly cat syndrome", this non-progressive neurological disorder is typically caused by the dam contracting feline distemper while pregnant. Causes general uncoordinated movement in a cat (usually described as "jerky" or "tremors"). This disorder is not fatal and most cats with CH live perfectly normal, healthy lives despite their motor quirks.
  
  "Wobbly cats" tend to find their own way of moving through the world without much outside help, particularly seen with wide stances, elongated strides, and an increased reliance on pulling oneself up instead of jumping.
  
  

  NARCOLEPSY

  More specifically "narcolepsy with cataplexy", this condition is categorized as a chronic sleep disorder with sudden loss of muscle control. Cats affected will most likely present with symptoms of excessive daytime tiredness, sudden muscle control loss / collapse, poor sleep quality, sleep paralysis (twitching / rapid eye movement during sleep), rapid returns to consciousness. and hypnagogic hallucinations - just to name a few. Narcolepsy in cats is rare and typically hard to diagnose without veterinarian expertise, and there is no cure for this condition. However, narcolepsy does not heavily impact a cat's quality of life and can safely be assumed as non-fatal.