Question: A Manx cat has what feature that affects its body type?

Context paragraphs:
Manx cat: The Manx cat ( , in earlier times often spelled Manks), is a breed of domestic cat ("Felis catus") originating on the Isle of Man, with a naturally occurring mutation that shortens the tail.  Many Manx have a small stub of a tail, but Manx cats are best known as being entirely tailless; this is the most distinguishing characteristic of the breed, along with elongated hind legs and a rounded head.  Manx cats come in all coat colours and patterns, though all-white specimens are rare, and the coat range of the original stock was more limited.  Long-haired variants are sometimes considered a separate breed, the Cymric.  Manx are prized as skilled hunters, and thus have often been sought by farmers with rodent problems, and been a preferred ship's cat breed.  They are said to be social, tame and active.  An old local term for the cats on their home island is stubbin.  Manx have been exhibited in cat shows since the 1800s, with the first known breed standard published in 1903.

Peta (cat): Manninagh KateDhu, commonly known as Peta, was the Chief Mouser to the Cabinet Office of the United Kingdom government between 1964 and sometime between 1969 and 1976, and was the first female cat in that role.  She became the replacement to Peter III, who had died at the age of 16 in 1964.  After Peter III's death, the Lieutenant Governor of the Isle of Man, Sir Ronald Garvey, suggested that a Manx cat be his replacement, and sent Peta to the Cabinet.  She was noted to be lazy and loud, and by 1969, some civil servants tried to remove her from Cabinet, but this did not happen, because of the suspected bad publicity that this action would incur.  She was not heard of again, until a reply to a member of the public in 1976 revealed that she had retired to the home of a civil servant.  Her successor was Wilberforce, who became the next Chief Mouser in the 1970s.

Meyers Manx: The Meyers Manx dune buggy is a small recreationally-oriented automobile, designed initially for desert racing by Californian engineer, artist, boat builder and surfer Bruce F. Meyers.  It was produced by his Fountain Valley, California company, B. F. Meyers & Co. from 1964 to 1971, in the form of car kits applied to shortened chassis of Volkswagen Beetles.  The car line dominated dune racing in its time, breaking records immediately, and was eventually also released in street-oriented models, until the company's demise due to tax problems after Meyers's departure.  New vehicles inspired by the original Manx buggy have been produced by Meyers's re-founded operation, Meyers Manx, Inc., since 2000.  The name and cat logo of the brand derives from the Manx cat, by virtue of the tailless breed's and the shortened vehicle's truncated "stubbiness".

Manxmouse: Manxmouse: The Mouse Who Knew No Fear is a 1968 children's novel by Paul Gallico.  The plot is an epic narrative of the adventures of a creature called a Manx Mouse as he meets and interacts with other people, climaxing in a meeting with a Manx cat who characters say is destined to eat him.

Kurilian Bobtail: The Kurilian Bobtail is a cat breed (or breed group, depending on registry) originating from the Kuril Islands, as well as Sakhalin Island and the Kamchatka peninsula of Russia.  Short- or long-haired, it has a semi-cobby body type and a distinct short, fluffy tail.  The back is slightly arched with hind legs longer than the front, similar to those of the Manx.  The breed is also called the Kuril Islands Bobtail, Kuril Bobtail (both often misspelled "Kurile") and Curilsk Bobtail, and may be referred to without "Bobtail".  It is sometimes also spelled Kurilean.  The original short-haired variant is a natural breed, known on the islands for over 200 years.  As selectively bred pets, they have been popular in Russia and to some extent other parts of Europe, especially for their rodent-hunting abilities, since the middle of the 20th century, but remain rare in North America as of 2011 .

Cat body-type mutation: Cats, like all living organisms, occasionally have mutations that affect their body type.  Sometimes, these cat body-type mutations are striking enough that humans select for and perpetuate them.  This is not always in the best interests of the cat, as many of these mutations are harmful; some are even lethal in their homozygous form.

Extinct animals from the Isle of Man: Some animal species and breeds once existed on the Isle of Man but are now extinct.  Some plant species have also been included at the end of this article.  There are no known specimens of the following breeds of dog, cattle, pig, horse and sheep.  Today only the Manx cat, Manx Loaghtan, Manx robber fly, Isle of Man cabbage and Manx marvel tomato exist as native breeds / types of the Isle of Man.

Elliot Abravanel: Elliot D. Abravanel is an American physician and diet counselor, who developed the "Body Type" system for weight loss and overall wellness.  Based on his experience with the "Skinny School" program in the 1970s and 1980s, the Body Type program is described in the book "Dr. Abravanel's Body Type Diet and Lifetime Nutrition Plan".  First published in 1985, the book was rereleased in 1999 with an exercise video.

Cymric cat: The Cymric ( or ) is a breed of domestic cat.  Some cat registries consider the Cymric simply a semi-long-haired variety of the Manx breed, rather than a separate breed.  Except for the length of fur, in all other respects the two varieties are the same, and kittens of either sort may appear in the same litter.  The name comes from "Cymru" (] ), the indigenous Welsh name of Wales, though the breed is not associated with Wales, and the name was possibly given as an attempt to provide a "Celtic"-sounding name for the breed.  The breed's Manx bloodline originated in the Isle of Man, though Canada claims to have developed the long-haired variant.  The breed is called the Longhair Manx or a similar name by some registries.

American Bobtail: The American Bobtail is an uncommon breed of domestic cat which was developed in the late 1960s.  It is most notable for its stubby "bobbed" tail about one-third to one-half the length of a normal cat's tail.  This is the result of a cat body type genetic mutation affecting the tail development, similar to that of a Manx cat.  The breed is not related to the Japanese Bobtail despite the similar name and physical type—the breeding programs are entirely unrelated, and the genetic mutation causing the bobbed tail are known to be different because the mutation causing the American Bobtail's tail is dominant, whereas the Japanese Bobtail tail mutation is recessive.

Supporting paragraphs: Manx cat Cat body-type mutation
Answer: tailless