Dysmelia can be caused by

- inheritance of abnormal genes, e.g. polydactyly, ectrodactyly or brachydactyly, symptoms of deformed limbs then often occur in combination with other symptoms (syndromes)

- external causes during pregnancy (thus not inherited), e.g. via amniotic band syndrome

- teratogenic drugs (e.g. thalidomide, which causes phocomelia) or environmental chemicals

- ionizing radiation (nuclear weapons, radioiodine, radiation therapy)

- infections

- metabolic imbalance

Dysmelia can refer to

- missing (aplasia) limbs: amelia, oligodactyly, congenital amputation e.g. Tibial or Radial aplasia

- malformation of limbs: shortening (micromelia, rhizomelia or mesomelia), ectrodactyly, phocomelia, meromelia, syndactyly, brachydactyly, club foot

- too many limbs: polymelia, polydactyly, polysyndactyly

- others: Tetraamelia, hemimelia, Symbrachydactyly

Life expectancy for individuals with hypochondroplasia is normal; the maximum height is about 147 cm or 4.8 ft.

The complete or partial absence of the pectoralis muscle is the malformation that defines Poland Syndrome. It can be treated by inserting a custom implant designed by CAD (computer aided design). A 3D reconstruction of the patient's chest is performed from a medical scanner to design a virtual implant perfectly adapted to the anatomy of each one. The implant is made of medical silicone unbreakable rubber. This treatment is purely cosmetic and does not make up for the patient's imbalanced upper body strength.

The Poland syndrome malformations being morphological, correction by custom implant is a first-line treatment. This technique allows a wide variety of patients to be treated with good outcomes. Poland Syndrome can be associated with bones, subcutaneous and mammary atrophy: if the first, as for pectus excavatum, is successfully corrected by a custom implant, the others can require surgical intervention such as lipofilling or silicone breast implant, in a second operation.

The surgery takes place under general anaesthesia and lasts less than 1 hour. The surgeon prepares the locus to the size of the implant after performing a 8-cm axillary incision and inserts the implant beneath the skin. The closure is made in 2 planes.

The implant will replace the pectoralis major muscle, thus enabling the thorax to be symmetrical and, in women, the breast as well. If necessary, especially in the case of women, a second operation will complement the result by the implantation of a breast implant and / or lipofilling.

Lipomodelling is progressively used in the correction of breast and chest wall deformities. In Poland syndrome, this technique appears to be a major advance that will probably revolutionize the treatment of severe cases. This is mainly due to its ability to achieve previously unachievable quality of reconstruction with minimal scaring.

In regards to treatment of hypochondroplasia usually takes the form of orthopedic surgery and physical therapy. Genetic counseling is advised for individuals and their families. Specifically in the case of spinal stenosis, one option is laminectomy.

The term squitten is generally used to refer to cats with the condition radial hypoplasia (underdeveloped radius bones) or foreleg micromelia (small forelegs) and related conditions known as radial aplasia (absent radius bones), radial agenesis (failure of radius bones to form) that produces stunted forelegs. The mutation sometimes occurs in the random-breeding population, particularly in inbred populations where recessive genes may be exhibited. Such cats have also been called twisty cats; In the late 1990s, several were deliberately bred at Karma Farms, a horse farm and cattery in Marshall, Texas, resulting in a public outcry against the operators of the farm.

Radial hypoplasia is related to one form of polydactyly, sometimes called patty feet or hamburger feet by cat lovers to distinguish them from thumb cat polydactyls. Ordinary mitten cat polydactyls are not affected.

Cats with radial hypoplasia or similar mutations often sit on their rump with their forelegs unable to touch the floor; this gives them a resemblance to a squirrel or kangaroo. This raises special care considerations for owners of affected cats. Kittens may be unable to knead effectively with their short forelegs; kneading is required to stimulate milk flow in the mother. The short or twisted forelegs cause mobility problems and such cats may adapt by using their hindlegs in a hopping gait.

A corresponding condition affecting the hind legs is called femoral hypoplasia and has only been reported three times in cats.

Typical characteristics of a squitten are short forelegs, with a short radius and ulna which may be twisted or absent, extra front toes, and normal-length hind legs.

A squitten is a cat with unusually short forelegs and/or unusually long hind legs that resembles a squirrel. It is an example of a cat body type genetic mutation. The word is a portmanteau of squirrel and kitten.

The term kangaroo cat is also, rarely, used; this derives from a 1953 specimen known as the Stalingrad Kangaroo Cat.

Microlissencephaly is listed in Orphanet database as a rare disease. There is no much information available about the epidemiology of microlissencepahly in literature. A PhD thesis has estimated the prevalence of microlissencepahly in South–Eastern Hungary between July 1992 and June 2006 to be a case every 91,000 live births (0.11:10,000).

In 1976, the first syndrome with MLIS was reported, now known as Norman–Roberts syndrome (MLIS type A). The Barth type (MLIS type B) was for the first time described in 1982 in two siblings who died soon after birth.