Dwarfism

This article is about the medical condition. For the legendary creature, see dwarf. For insular dwarfism and other uses, see Dwarf (disambiguation).

Dwarfism
Specialty	Medical genetics

Dwarfism (pronounced dwo[ʀ]fiz'm /ˈdwɔːˌfɪzɪm/) is a medical term describing a person of short stature, with the most widely accepted definition of a dwarf (pl: dwarfs) being a person with an adult height of less than 4 feet 10 inches (147 cm). Dwarfism can be caused by over 200 distinct medical conditions, and as such the symptoms and characteristics of individual dwarfs vary greatly. People who are affected by dwarfism are often referred to as "little people."

Disproportionate dwarfism is identified by one or more body parts being disproportionately large or small compared to the rest of the body, with growth abnormalities in specific areas being apparent. In cases of proportionate dwarfism the body parts are proportional to each other with a general lack of growth being apparent. Hypotonia, or a lack of muscle, is common in dwarfs, but intelligence and lifespan are usually normal.

The most common cause of dwarfism is achondroplasia, a bone growth disorder, which is responsible for 70% of dwarfism cases. In cases of achondroplasia the limbs are disproportionally short compared to the trunk (abdomen area), with the head larger than normal and unique facial characteristics. Conditions in humans characterized by disproportional body parts are typically caused by one or more genetic disorders in bone or cartilage development. Forms of extreme shortness in humans characterized by proportional body parts usually have a hormonal cause such as growth hormone deficiency, once known as "pituitary dwarfism".

There is no universal treatment for dwarfism. Individual abnormalities such as bone growth disorders can sometimes be treated through surgery, and some hormone disorders can be treated through medication, but in most cases it is impossible to treat all of the symptoms of dwarfism. Most of the time lifestyle changes are needed to cope with the effects of dwarfism. In-home devices like specialized furniture is often needed to help people who have dwarfism function normally. Many support groups exist to help sufferers of dwarfism cope with the challenges they face, and to help them develop strategies to become independent.

Dwarfism is a highly visible condition that often carries negative connotations in society. Some believe people afflicted with dwarfism are intellectually challenged or have personality disorders. Due to their unusual height, people with dwarfism are often used as spectacles in entertainment or portrayed with derogatory stereotypes. In popular culture, dwarfs are frequently portrayed in roles directly related to their abnormal height. Heightism is a serious problem that can lead to ridicule as a child and discrimination as an adult for a person with dwarfism.

Classification

Dwarfism is a medical disorder with the sole requirement being an adult height of under 4 feet 10 inches (147 cm) and is almost always classified in regards to the underlying condition that is the cause for the short stature. Dwarfism is not necessarily caused by disease or a genetic disorder, it can simply be a naturally occurring part of a person's genetics. If dwarfism is caused by a medical disorder, the person is diagnosed and referred to by the underlying disorder. Disorders causing dwarfism are often classified by proportionality. Disproportionate dwarfism describes disorders that cause abnormal proportions of the body parts, while proportionate dwarfism results in a generally uniform stunting of the body.

Disorders that cause dwarfism may be classified according to one of hundreds of names, which are usually permutations of the following roots:

• location
  • rhizomelic = root, e.g. bones of upper arm or thigh
  • mesomelic = middle, e.g. bones of forearm or lower leg
  • acromelic = end, e.g. bones of hands and feet.
  • micromelic = entire limb shortened
• source
  • chondro = of cartilage
  • osteo = of bone
• spondylo = of the vertebrae
• plasia = form
• trophy = growth

Examples include achondroplasia, osseous dysplasia, chondrodystrophy, and osteochondrodystrophy.

Characteristics

The universal defining characteristic of dwarfism is an adult height of less than 4 feet 10 inches. Since those afflicted with dwarfism have such a wide range of physical characteristics, oddities in individuals are understood by diagnosing and observing the underlying disorders.

Disproportionate dwarfism is characterized by one or more body parts being disproportionately large or small compared to the rest of the body. In achondroplasia the trunk is normally sized with the limbs being disproportionately short, the head being larger than usual, and the forehead being prominent. Facial features are often affected and individual body parts may have problems associated with them. Orthopedic problems can arise across multiple conditions such as diastrophic dysplasia and pseudoachondroplasia.

Proportionate dwarfism is marked by body parts being proportional but stunted. Height is significantly below average and there may be long periods without any significant growth. Sexual development is often delayed or impaired into adulthood. Unlike disproportionate dwarfism, mental capacity may be diminished in some cases of proportionate dwarfism. The overall stunted growth can lead to impaired intelligence when compared to the physical age.

Physical maleffects of malformed bones vary according to the specific disease. Many involve joint pain caused by abnormal bone alignment, or from nerve compression (e.g., spinal stenosis). Early degenerative joint disease, exaggerated lordosis or scoliosis, and constriction of spinal cord or nerve roots can cause pain and disability. Reduced thoracic size can restrict lung growth and reduce pulmonary function. Some forms of dwarfism are associated with disordered function of other organs, such as the brain or liver, sometimes severely enough to be more disabling than the abnormal bone growth.

Mental effects also vary according to the specific underlying syndrome. In most cases of skeletal dysplasia, such as achondroplasia, mental function is not impaired in any way. However, there are syndromes which can affect the cranial structure and growth of the brain, severely impairing mental capacity. Unless the brain is directly affected by the underlying disorder, there is little to no chance of mental impairment that can be attributed to dwarfism.

Causes

Dwarfism can result from a myriad of different medical conditions, each with its own separate symptoms and causes. Two disorders, achondroplasia and growth hormone deficiency (also known as pituitary dwarfism), are responsible for the majority of dwarfism cases.

Achondroplasia

Further information: [[:Achondroplasia]]

The most recognizable and most common form of dwarfism is achondroplasia, which accounts for 70% of dwarfism cases and produces rhizomelic short limbs, increased spinal curvature, and distortion of skull growth. Achondroplasia is an autosomal dominant disorder caused by a faulty allele being present in a person's genome. If a pair of achondroplasia alleles are present, the result is fatal. Achondroplasia is a mutation in the fibroblast growth factor receptor gene 3 (FGFR3), which is an inhibitor that regulates bone growth. In cases of achondroplasia, the FGR3 gene is too aggressive, negatively impacting bone growth.

Growth hormone deficiency

Further information: [[:Growth hormone deficiency]]

Growth hormone deficiency (GHD) is a medical condition in which the body produces insufficient growth hormone. Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction. If a lack of this hormone is present, stunted or even halted growth may become apparent. Children with this disorder may grow slowly and puberty may be delayed by several years, or even indefinitely. Growth hormone deficiency has no single definite cause. It can be caused by mutations of specific genes, damage to the pituitary gland, Turner's syndrome, poor nutrition, or even stress (leading to psychogenic dwarfism).

Other

Other causes of dwarfism include Spondyloepiphyseal dysplasia congenita, Diastrophic dysplasia, Pseudoachondroplasia, Hypochondroplasia, Primordial dwarfism, Turner syndrome, and Osteogenesis imperfecta (OI). Severe shortness with skeletal distortion also occurs in several of the mucopolysaccharidoses and other storage disorders.

Diagnosis

Dwarfism is often diagnosed in childhood due to the visible nature of the condition. A physical examination can usually diagnose a type of dwarfism, but genetic testing and diagnostic imaging may be used to determine the exact condition. In a person's youth, growth charts that track height can be used to diagnose subtle forms of dwarfism that have no striking physical characteristics.

Short stature or stunted growth during youth is usually what brings the condition to medical attention. Skeletal dysplasia is usually suspected because of obvious physical features (e.g., unusual configuration of face or shape of skull), because of an obviously affected parent, or because body measurements (arm span, upper to lower segment ratio) indicate disproportion. Bone x-rays are often key to diagnosing a specific skeletal dysplasia, but are not the sole diagnostic tool to identify dysplasias. Most children with suspected skeletal dysplasias will be referred to a genetics clinic for diagnostic confirmation and genetic counseling. In the last decade, genetic tests for some of the specific disorders have become available.

During the initial medical evaluation for shortness, the absence of disproportion and the other clues above usually indicates other causes than bone dysplasias. Extreme shortness with completely normal proportions sometimes indicates growth hormone deficiency (pituitary dwarfism).

Short stature alone, in the absence of any other abnormalities, may be the result of the distribution of offspring height from short-statured parents, rather than a symptom of any medical condition.

Prevention

Many types of dwarfism are impossible to prevent due to them being based on genetic factors. Genetic conditions that cause dwarfism may be identified with genetic testing, by screening for the specific abnormalities that result in the condition. However, due to the myriad of conditions that cause dwarfism it may be impossible to definitively determine if a child will be born with dwarfism.

Conditions of dwarfism resulting from malnutrition or a hormonal abnormality may be treated through proper dieting or hormonal therapy. Growth hormone deficiency may be remedied via injections of Human Growth Hormone (HGH) during the early years of life, but the HGH injections may adversely affect the cardiac muscles, making them too large or thick to properly function, causing death through cardiac failure in the patient.

Management

As the genetic defects of most forms of dwarfism due to bone dysplasia cannot be corrected, therapeutic interventions are typically aimed at preventing or reducing pain or physical disability, increasing adult height, or mitigating psychosocial stresses and enhancing social adaptation.

Forms of dwarfism associated with the endocrine system may be treated using hormonal therapy. If the cause is prepubescent hyposecretion of growth hormone, supplemental growth hormone may correct the abnormality. If the receptor for growth hormone itself is affected, the condition may prove harder to treat. Hypothyroidism is another possible cause of dwarfism that can be treated through hormonal therapy. Injections of thyroid hormone can mitigate the effects of the condition, but physical complications may be permanent.

Pain and disability may be ameliorated by physical therapy, braces or other orthotic devices, or by surgical procedures. The only simple interventions that increase perceived adult height are dress enhancements, such as shoe lifts or hairstyle. Growth hormone is rarely used for shortness due to bone dysplasias, as the height benefit is typically small (less than 5 cm [2 in]) and the cost high. The most effective means of increasing adult height by several inches is limb-lengthening surgery, though availability is limited and cost is high in terms of money, discomfort, and disruption of life. Most people with dwarfism do not choose this option; it remains controversial. For other types of dwarfism, surgical treatment is not possible.

Society and culture

File:Velazquez-dwarf-don-sebastian-de-morra.jpg

The Dwarf Don Sebastián de Morra, by Velázquez.

Terminology

Historically ambiguous, the appropriate term for describing a person of particularly short stature (or specifically with the genetic condition achondroplasia) developed euphemistically over the past few centuries.

"Midget," whose etymology indicates a "small sandfly," came into prominence in the mid-1800s after Harriet Beecher Stowe used it in her novels Sunny Memories of Foreign Lands and Old Town Folks where she described children and an extremely short man, respectively. Later, the word was deemed offensive because it was the descriptive term applied to P.T. Barnum's dwarfs used for public amusement during the freak show era. It is also not considered accurate as it is not a medical diagnosis, though it is sometimes used to describe those who are particularly short but still proportional.

The first notable use of the term "dwarf" was by the Brothers Grimm in their fairy tale Little Snow White; Jonathan Swift also used it in Gulliver's Travels to describe a giant who was only 20 ft tall compared to his 40 ft peers. The plural form of "dwarf" for a person with dwarfism is "dwarfs", while "dwarves" describes the mythical creature. Dwarf too has been condemned by some as inaccurate and insensitive because of its mythical and fairy tale origins.

The terms "dwarf", "little person", "LP", and "person of short stature" are considered acceptable by most at this point in time.

Art and media depictions

See also: List of Dwarfism media depictions and List of people with dwarfism

When depicted in art, literature, or movies, dwarfs are rarely depicted as "regular people who are very short" but often as a species apart. Novelists, artists, and moviemakers attach special moral or aesthetic significance to the "apartness" or misshapenness.

Artistic representations of dwarfism can be found on Greek vases and other ancient artefacts, including ancient Egyptian art. Depiction of dwarfs is also found in European paintings and many illustrations. Many European paintings (especially Spanish) of the 16th–19th centuries depict dwarfs by themselves or with others. In the Talmud, it is said that the second born son of the Egyptian Pharaoh of the Bible was a dwarf. Recent scholarship has suggested ancient Egyptians held dwarfs in high esteem. Several important mythological figures of the North American Wyandot nation are portrayed as dwarfs.

As popular media has become more widespread the amount of works depicting dwarfs has risen dramatically. Some feel that dwarf characters are often depicted based on the novelty factor of their stature rather than other personal attributes. Dwarfism is depicted in many books, films, and TV series such as Austin Powers, Gulliver's Travels by Jonathan Swift, Charlie and the Chocolate Factory, Little People Big World, Willow, Harry Potter, Seinfeld, and The Tin Drum by Günter Grass.

See also

• Ellis-van Creveld syndrome
• Gigantism
• Laron syndrome
• Mulibrey nanism

External links

• Little People of America
• Restricted Growth Association UK
• Little People: A Father Reflects on His Daughter's Dwarfism — and What It Means to Be Different, by Dan Kennedy. Critically acclaimed book in a free online edition.