Dwarfism

Dwarfism
Classification and external resources
A man with what appears to be a form of SED (Spondyloepiphyseal Dysplasia). His fingers are similar in size to those of a person of normal height. One of the symptoms is a set of characteristic facial features.
ICD-10	E23.0, E34.2, E45.0, Q77.4
ICD-9	253.3, 259.4
DiseasesDB	80
MedlinePlus	001176
MeSH	D004392

Dwarfism (pronounced /ˈdwɔrfɪzəm/) is short stature resulting from an particular medical condition. It is sometimes defined as an adult height of less than 4 feet 10 inches (147 cm),^[1] although this definition is problematic because short stature in itself is not a disorder.

Dwarfism can be caused by about 200 distinct medical conditions,^[2] such that the symptoms and characteristics of individual people with dwarfism vary greatly. In the United States and Canada, many people with dwarfism prefer to be called little people.^[3]

Disproportionate dwarfism is characterized by one or more body parts' being relatively large or small in comparison to those of a normal adult, with growth abnormalities in specific areas being apparent. In cases of proportionate dwarfism, the body appears normally proportioned, but is abnormally small. Historically, the term midget was used to describe "proportionate dwarfs"; however, this term has now become offensive and pejorative (see terminology). Hypotonia, or a lack of muscle, is common in dwarfs, but intelligence and lifespan are usually normal.

Achondroplasia is a bone-growth disorder responsible for 70% of dwarfism cases.^[1] In achondroplasia, the limbs are disproportionally short compared to the trunk (abdominal area), with the head larger than normal and characteristic facial features. Conditions in humans characterized by disproportional body parts are typically caused by one or more genetic disorders in bone or cartilage development. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth-hormone deficiency, once called pituitary dwarfism.^[3][4]

There is no single treatment for dwarfism. Individual abnormalities, such as bone-growth disorders, sometimes can be treated through surgery, and some hormone disorders can be treated through medication, but usually it is impossible to treat all the symptoms of dwarfism. Lifestyle changes often are needed to cope with the effects of dwarfism. Such devices as specialized furniture often help people with dwarfism to function normally.^[5] Many support groups help sufferers of dwarfism cope with the challenges they face and with developing and maintaining their independence.^[6]

Dwarfism is a highly visible condition and often carries negative connotations in society. Because of their unusual height, people with dwarfism are often used as spectacles in entertainment and portrayed with stereotypes. For a person with dwarfism, heightism can lead to ridicule in childhood and discrimination in adulthood.^[7][8]

Short stature can be inherited without any coexisting disease. Short stature in the absence of any abnormal medical condition is not generally considered dwarfism. For example, a short man and a short woman who are in normal health will tend to produce children who are also short and in normal health. While short parents tend to produce short children, persons with dwarfism may produce children of normal height, if the cause of their dwarfism is not genetically transmissible or if the individual does not pass on the genetic mutation.

Classification

Dwarfism is a medical disorder with the sole requirement being an adult height under 4 feet 10 inches (147 cm) and it is almost always classified as 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 consequence of a person's genetics. If dwarfism is caused by a medical disorder, the person is referred to by the underlying diagnosed 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 the upper arm or thigh
  • mesomelic = middle, e.g., bones of the forearm or lower leg
  • acromelic = end, e.g., bones of hands and feet.
  • micromelic = entire limbs are shortened
• source
  • chondro = of cartilage
  • osteo = of bone
  • spondylo = of the vertebrae
  • plasia = form
  • trophy = growth

Examples include achondroplasia, osseous dysplasia, chondrodystrophy, and osteochondrodystrophy.^[9]

Characteristics

A typical defining characteristic of dwarfism is an adult height of less than 1.47 m (4 feet 10 inches). Since those with dwarfism have such a wide range of physical characteristics, oddities in individuals are identified by diagnosing and monitoring 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.^[4] Facial features are often affected and individual body parts may have problems associated with them. Orthopedic problems can result from multiple conditions such as diastrophic dysplasia and pseudoachondroplasia.

Proportionate dwarfism is marked by body parts being proportional but stunted.^[10] 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).^[3] Early degenerative joint disease, exaggerated lordosis or scoliosis, and constriction of spinal cord or nerve roots can cause pain and disability.^[11] 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.^[12][13]

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.^[10] 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.^[14]

The psychosocial disadvantages may be more distressing than the physical symptoms, especially in childhood and adolescence, but people with dwarfism vary greatly in the degree to which social participation and emotional health are affected.

• Social prejudice against extreme shortness may reduce social and marital opportunities.^[15][16]
• Numerous studies have demonstrated reduced employment opportunities. Severe shortness is associated with lower income.^[16]
• Self-esteem may suffer and family relationships may be affected.
• Extreme shortness (in the low 2–3 foot [60–90 cm] range) can interfere with ordinary activities of daily living, like driving or using countertops built for taller people. Other symptoms of dwarfism such as bowed knees and unusually short fingers can lead to back problems, difficulty in walking, and handling objects.
• Children with dwarfism are particularly vulnerable to teasing and ridicule from classmates. Because dwarfism is relatively uncommon, children may feel isolated from their peers.^[12]

Causes

Dwarfism can result from myriad 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.^[2]

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 the presence of a faulty allele 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.^[17]

Research by urologist Harry Fisch of the Male Reproductive Center at Columbia Presbyterian Hospital indicates that this defect may be exclusively inherited from the father and becomes increasingly probable with paternal age; specifically males reproducing after 35. ^[18]

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 this hormone is lacking, 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,^[19] or even stress (leading to psychogenic dwarfism).

Other

Other causes of dwarfism include spondyloepiphyseal dysplasia congenita, diastrophic dysplasia, pseudoachondroplasia, hypochondroplasia, Noonan syndrome, primordial dwarfism, Turner syndrome, osteogenesis imperfecta (OI) and hypothyroidism. Severe shortness with skeletal distortion also occurs in several of the Mucopolysaccharidoses and other storage disorders.^[20]

Serious chronic illnesses may produce dwarfism as a side effect. Harsh environmental conditions, such as malnutrition, may also produce dwarfism. These types of dwarfism are indirect consequences of the generally unhealthy or malnourished condition of the individual, and not by any specific disease. The dwarfism often takes the form of simple short stature, without any deformities. In societies where poor nutrition is widespread, the average height of the population may be reduced below its genetic potential by the lack of proper nutrition.

Diagnosis

Dwarfism is often diagnosed in childhood on the basis of visible symptoms. A physical examination can usually suffice to diagnose certain types of dwarfism, but genetic testing and diagnostic imaging may be used to determine the exact condition.^[21] In a person's youth, growth charts that track height can be used to diagnose subtle forms of dwarfism that have no other striking physical characteristics.^[2]

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.^[21] Bone X-rays are often key to diagnosing a specific skeletal dysplasia, but are not the sole diagnostic tool. Most children with suspected skeletal dysplasias are referred to a genetics clinic for diagnostic confirmation and genetic counseling. Since about the year 2000, genetic tests for some of the specific disorders have become available.^[22]

During an initial medical evaluation of shortness, the absence of disproportion and other clues listed above usually indicates causes other than bone dysplasias. Extreme shortness with completely normal proportions sometimes indicates growth hormone deficiency (pituitary dwarfism).^[23]

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.^[24]

Prevention

Many types of dwarfism are impossible to prevent because they are genetically caused. 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 number of causes of dwarfism, it may be impossible to determine definitively if a child will be born with dwarfism.

Dwarfism resulting from malnutrition or a hormonal abnormality may be treated with an appropriate diet or hormonal therapy. Growth hormone deficiency may be remedied via injections of Human Growth Hormone (HGH) during early life.

Management

Genetic defects of most forms of dwarfism caused by bone dysplasia cannot be corrected, so therapeutic interventions are typically aimed at preventing or reducing pain or physical disability, increasing adult height, or mitigating psychosocial stresses and enhancing social adaptation.^[6]

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 is itself 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.^[6] 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 caused by bone dysplasias, since the height benefit is typically small (less than 5 cm [2 in]) and the cost high.^[5] The most effective means of increasing adult height by several inches is distraction osteogenesis, though availability is limited and the cost is high in terms of money, discomfort, and disruption of life. Most people with dwarfism do not choose this option, and it remains controversial.^[3] For other types of dwarfism, surgical treatment is not possible.

Society and culture

The Dwarf Don Sebastián de Morra, by Velázquez.

Terminology

The appropriate term for describing a person of particularly short stature (or with the genetic condition achondroplasia) has historically been ambiguous, and has developed euphemistically over the past few centuries.

"Midget", whose etymology indicates a "small sandfly,"^[25] 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.^[4] Later most people of short stature considered the word to be offensive because it was the descriptive term applied to P. T. Barnum's dwarfs used for public amusement during the freak show era.^[3] It is also not considered accurate as it is not a medical term or diagnosis, though it is sometimes used as a slang term to describe those who are particularly short, whether or not they have dwarfism.^[26]

The first notable use of the term "dwarf" was by the Brothers Grimm in their fairy tale Snow White;^[27] 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.^[28] The word "dwarf" has also been condemned by some as not only inaccurate but also insensitive due to its mythical and fairy tale origins.^[3]

The terms "dwarf", "little person", "LP", and "person of short stature" are now generally considered acceptable by most people affected by these disorders.^[4]

Art and media depictions

Seneb, dwarf priest of funerary cults in 4th Dynasty (c. 2640-2510 BCE) Ancient Egypt, with his wife Senetites and their children.^[29]

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

Artistic representations of dwarfism can be found on Greek vases and other ancient artifacts, including ancient Egyptian art in which dwarfs are likely to have been seen as a divine manifestation, with records indicating they could reach high positions in society.^[30][31]

The Bhagavat Purana Hindu text devotes nine chapters to the adventures of Vamana, a dwarf avatar of Vishnu.

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.^[32] Recent scholarship has suggested that ancient Egyptians held dwarfs in high esteem.^[33] Several important mythological figures of the North American Wyandot nation are portrayed as dwarfs.^[34]

As popular media have become more widespread, the number of works depicting dwarfs has increased dramatically. Some feel that dwarf characters are often depicted based on the novelty factor of their stature rather than on other personal attributes. Dwarfism is depicted in many books, films, and TV series such as Austin Powers, Gulliver's Travels by Jonathan Swift^[35], The Wizard of Oz, Willy Wonka and the Chocolate Factory, Little People Big World, The Little Couple, Harry Potter, Seinfeld, In Bruges, The Tin Drum by Günter Grass, and the film The Station Agent.

The Animal Planet TV series Pit Boss features dwarf actor "Shorty" Rossi and his talent agency, "Shortywood Productions", which Rossi uses to provide funding for his pit bull rescue operation, "Shorty's Rescue". Rossi's three full-time employees, featured in the series, are all Little People and aspiring actors.

See also

• Gigantism
• Human height
• Ellis–van Creveld syndrome
• Laron syndrome
• Mulibrey nanism
• List of people with dwarfism
• List of shortest people
• Our Little Life (reality television show)

References

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.

• Media related to Dwarfism at Wikimedia Commons