Dwarfism (midget) is a condition characterized by short stature. Technically, that means an adult height of 4 feet 10 inches or under. A woman with dwarfism can give birth to a normal child, even if the father is 7 feet tall.
Achondroplasia is a common cause of dwarfism. It occurs as a sporadic mutation in approximately 75% of cases (associated with advanced paternal age) or may be inherited as an autosomal dominant genetic disorder.
People with achondroplasia have short stature, with an average adult height of 131 centimeters (51.5 inches) (4 ft 3.5 in) for males and 123 centimeters (48.4 inches) (4 ft 0.4 in) for females. Achondroplastic adults are known to be as short as 62.8 cm (24.7 inches) [2 ft 0.7 in]. The disorder itself is caused by a change in the DNA for fibroblast growth factor receptor 3 (FGFR3), which causes an abnormality of cartilage formation. If both parents of a child have achondroplasia, and both parents pass on the mutant gene, then it is very unlikely that the homozygous child will live past a few months of its life. The prevalence is approximately 1 in 25,000.
Achondroplasia is caused by a mutation in Fibroblast growth factor receptor 3 (FGFR3). In normal development FGFR3 has a negative regulatory effect on bone growth. In achondroplasia, the mutated form of the receptor is constitutively active and this leads to severely shortened bones. The effect is genetically dominant, with one mutant copy of the FGFR3 gene being sufficient to cause achondroplasia, while two copies of the mutant gene are invariably fatal before or shortly after birth. A person with achondroplasia thus has a 50% chance of passing dwarfism to each of their offspring. People with achondroplasia can be born to parents that do not have the condition due to spontaneous mutation.
New gene mutations leading to achondroplasia are associated with increasing paternal age (over 35 years old). Studies have demonstrated that new gene mutations for achondroplasia are exclusively inherited from the father and occur during spermatogenesis; it is theorized that oogenesis has some regulatory mechanism that prevents the mutation occurring in females.
There are two other syndromes with a genetic basis similar to achondroplasia: hypochondroplasia and thanatophoric dysplasia.
Achondroplasia can be detected before birth by the use of prenatal ultrasound. A DNA test can be performed before birth to detect homozygosity, wherein two copies of the mutant gene are inherited, a lethal condition leading to stillbirths.
A skeletal survey is useful to confirm the diagnosis of achondroplasia. The skull is large, with a narrow foramen magnum, and relatively small skull base. The vertebral bodies are short and flattened with relatively large intervertebral disk height, and there is congenitally narrowed spinal canal. The iliac wings are small and squared, with a narrow sciatic notch and horizontal acetabular roof. The tubular bones are short and thick with metaphyseal cupping and flaring and irregular growth plates. Fibular overgrowth is present. The hand is broad with short metacarpals and phalanges, and a trident configuration. The ribs are short with cupped anterior ends. If the radiographic features are not classic, a search for a different diagnosis should be entertained. Because of the extremely deformed bone structure, people with achondroplasia are often "double jointed".
The diagnosis can be made by fetal ultrasound by progressive discordance between the femur length and biparietal diameter by age. The trident hand configuration can be seen if the fingers are fully extended.
Another distinct characteristic of the syndrome is thoracolumbar gibbus in infancy.
At present, there is no known treatment for achondroplasia, even though the cause of the mutation in the growth factor receptor has been found.
Although used by those without achondroplasia to aid in growth, human growth hormone does not help people with achondroplasia. However, if desired, the controversial surgery of limb-lengthening will lengthen the legs and arms of someone with achondroplasia.
Usually, the best results appear within the first and second year of therapy. After the second year of GH therapy, beneficial bone growth decreases. Therefore, GH therapy is not a satisfactory long term treatment.
Gene based therapy may possibly serve as a future treatment option. BioMarin Pharmaceutical Inc. recently announced the initiation of a Phase 1 study in healthy volunteers for BMN-111, an analog of C-type Natriuretic Peptide (CNP), for the treatment of achondroplasia.
Latest research and related efforts are tracked by the non-profit Growing Stronger.
Achondroplasia is one of 19 congenital conditions with similar presentations, such as osteogenesis imperfecta, multiple epiphyseal dysplasia tarda, achondrogenesis, osteopetrosis, and thanatophoric dysplasia. This makes estimates of prevalence difficult, with changing and subjective diagnostic criteria over time. One detailed and long-running study in the Netherlands found that the prevalence determined at birth was only 1.3 per 100,000 live births. However, another study at the same time found a rate of 1 per 10,000.
Based on their disproportionate dwarfism, some dog breeds traditionally have been classified as "achondroplastic." This is the case for the dachshund, basset hound, and bulldog breeds. Data from whole genome association studies in short-limbed dogs reveal a strong association of this trait with a retro-gene coding for fibroblast growth factor 4 FGF4. Therefore, it seems unlikely that dogs and humans are achondroplastic for the same reasons. However, histological studies in some achondroplastic dog breeds have shown altered cell patterns in cartilage that are very similar to those observed in humans exhibiting achondroplasia.
A similar form of achondroplasia was found in a litter of piglets from a phenotypically normal Danish sow. The dwarfism was inherted dominant in the offspring from this litter. The mutants were born phenotypically normal but became more and more symptomatic as they reached maturity.
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EDAR (EDAR Hypohidrotic ectodermal dysplasia)
Short stature refers to a height of a human being which is below expected. Shortness is a vague term without a precise definition and with significant relativity to context. Because of the lack of preciseness, there is often disagreement about the degree of shortness that should be called short.
The American Association of Clinical Endocrinologists defines "short stature" as height more than 2 standard deviations below the mean for age and gender, which corresponds to the shortest 2.3% of individuals.
Shortness in children and young adults nearly always results from below-average growth in childhood, while shortness in older adults usually results from loss of height due to kyphosis of the spine or collapsed vertebrae from osteoporosis.
From a medical perspective, severe shortness can be a variation of normal, resulting from the interplay of multiple familial genes. It can also be due to one or more of many abnormal conditions, such as chronic (prolonged) hormone deficiency, malnutrition, disease of a major organ system, mistreatment, treatment with certain drugs, chromosomal deletions, inherited diseases, birth defect syndromes, bone structures fusing earlier than intended or many other causes.
Human Growth Hormone (HGH) deficiency may occur at any time during infancy or childhood, with the most obvious sign being a noticeable slowing of growth. The deficiency may be genetic.
Among children without growth hormone deficiency, short stature may be caused by Turner syndrome, chronic renal insufficiency, being small for gestational age at birth, Prader–Willi syndrome, or other conditions. When the cause is unknown, it is called idiopathic short stature.
The decision to treat is based on a belief that the child will be disabled by being extremely short as an adult, so that the risks of treatment (including sudden death) will outweigh the risks of not treating the symptom of short stature. Although short children commonly report being teased about their height, most adults who are very short are not physically or psychologically disabled by their height.
Treatment is expensive and requires many years of injections with human growth hormones. The result depends on the cause, but is typically an increase in final height of about 5 to 10 centimetres (2.0 to 3.9 in) taller than predicted. Thus, treatment takes a child who is expected to be shorter than a normal adult, and produces an adult who is still obviously shorter than average.
Increasing final height in children with short stature may be beneficial and could enhance health-related quality of life (HRQoL) outcomes barring troublesome side effects and excessive cost of treatments.
The cost of treatment depends on the amount of growth hormone given, which in turn depends on the child's weight and age. One year's worth of drugs normally costs about US $20,000 for a small child and over $50,000 for a teenager.
From a social perspective shortness can be a problem independently of the cause. In many societies there are advantages associated with taller stature and disadvantages associated with shorter stature, and vice versa.
Pharmaceutical companies Genentech and Eli Lilly, makers of human growth hormone, have worked to medicalize short stature by convincing the public that short stature is a disease rather than a natural variation in human height. Limiting sales of the hormone to children diagnosed with growth hormone deficiency, rather than being short for any reason, limited their sales market. Expanding it to all children whose height was below the third percentile would create 90,000 new customers and US $10 billion in revenue. In the early 1990s, they paid two US charities, the Human Growth Foundation and the MAGIC Foundation, to measure the height of thousands of children in schools and public places, and to send letters urging medical consultations for children whose height was deemed low. Parents and schools were not told that the charities were being paid by the drug companies to do this.
Paired with a campaign to advertise the hormone to physicians, the campaign was successful, and tens of thousands of children began receiving HGH. About half of them do not have growth hormone deficiency, and consequently benefited very little, if at all, from the hormone injections. Criticism of the universal screening program eventually resulted in its end.
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occurs when an individual person or animal is short in stature resulting from a medical condition caused by abnormal (slow or delayed) growth. In humans, dwarfism is sometimes defined as an adult height of equal to or less than 147 cm (4 feet 10 inches) (58 inches).
Dwarfism can be caused by about 200 distinct medical conditions, such that the symptoms and characteristics of individuals with dwarfism vary greatly. Disproportionate
dwarfism is characterized by one or more body parts being relatively large or small in comparison to those of an average-sized adult, with growth variations in specific areas being apparent. In cases of proportionate
dwarfism, the body appears normally proportioned, but is unusually small.
There is no single treatment for dwarfism. Individual differences, such as bone growth disorders, sometimes can be treated through surgery, some hormone disorders can be treated through medication, and by hormone replacement therapy; this treatment must be done before the child's growth plates fuse. Individual accommodations, such as specialized furniture, are often used by people with dwarfism. Many support groups provide services to aid individuals with dwarfism in facing the challenges of an ableist society.
For people, in addition to the medical aspect of the condition, there are social and sociological aspects as well. In the United States, Canada and New Zealand, many people with dwarfism prefer to be called little people
Historically, the term midget
was used to describe "proportionate dwarfs"; however, this term is now sometimes regarded as offensive and pejorative (see terminology)
in people. Another definition for midget is any thing (especially an animal), that is small in proportion to a typical specimen. Hypotonia, or low muscle tone, is common in dwarfs, but intelligence and lifespan are usually normal. Defining dwarfism by height alone is problematic because short stature in itself is not a disorder. For example, pygmies have adult male heights of less than 150 cm (4 feet 11 inches) on average.
For a person with dwarfism, heightism can lead to ridicule in childhood and discrimination in adulthood.
Dwarfism is a medical disorder. In humans, the sole requirement is having an adult height under 147 cm (4 ft 10 in) and it is almost always classified with respect to the underlying condition that is the cause of the short stature. Dwarfism is usually caused by a genetic disorder; achondroplasia is caused by a mutation on chromosome four. 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 unusual 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:
Examples include achondroplasia, osseous dysplasia, chondrodystrophy, and osteochondrodystrophy.
A typical defining characteristic of dwarfism is an adult height of less than 147 cm (4 ft 10 in) Since those with dwarfism have such a wide range of physical characteristics, variations in individuals are identified by diagnosing and monitoring the underlying disorders.
It should be noted that short stature can be inherited without any coexisting disease. Short stature in the absence of a medical condition is not generally considered dwarfism. For example, a short man and a short woman with average health will tend to produce children who are also short and with average health. While short parents tend to produce short children, persons with dwarfism may produce children of average height, if the cause of their dwarfism is not genetically transmissible or if the individual does not pass on the genetic variation.
Disproportionate dwarfism is characterized by one or more body parts being unusually large or small compared to the rest of the body. In achondroplasia one's trunk is usually of average size, one's limbs being proportionately shorter, one's head usually larger, and a prominent forehead. In at least one case achondroplasia resulted in a significantly smaller trunk and head. 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 smaller. 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, in some cases intellectual disability may be a part of proportionate dwarfism.
Physical maleffects of malformed bones vary according to the specific disease. Many involve joint pain caused by abnormal bone alignment, or from nerve compression. 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 of an impairment than the unusual 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.
The psychosocial limitations of society may be more disabling 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.
Dwarfism can result from myriad medical conditions, each with its own separate symptoms and causes. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth-hormone deficiency, once called pituitary dwarfism
. Two disorders, achondroplasia and growth hormone deficiency (also known as pituitary dwarfism), are responsible for the majority of human dwarfism cases.
The most recognizable and most common form of dwarfism in humans is achondroplasia, which accounts for 70% of dwarfism cases and produces rhizomelic short limbs, increased spinal curvature, and distortion of skull growth. With achondroplasia, the body's limbs are proportionately shorter than the trunk (abdominal area), with a larger head than average and characteristic facial features. Achondroplasia is an autosomal dominant disorder caused by the presence of a faulty allele in the genome. If a pair of achondroplasia alleles are present, the result is fatal. Achondroplasia is a mutation in the fibroblast growth factor receptor 3, which is an inhibitor that regulates bone growth. In cases of achondroplasia, the FGFR3 gene is too aggressive, negatively impacting bone growth.
Research by urologist Harry Fisch of the Male Reproductive Center at Columbia Presbyterian Hospital indicates that in humans this defect may be exclusively inherited from the father and becomes increasingly probable with paternal age; specifically males reproducing after 35.
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 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 causes of dwarfism are 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.
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 of 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.
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. 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.
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. 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.
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).
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.
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 variation 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.
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.
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. 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. 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. For other types of dwarfism, surgical treatment is not possible.
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.
The noun dwarf
stems from Old English dweorg
, originally referring to a being from Germanic mythology—a dwarf—that dwells in mountains and in the earth, and is associated with wisdom, smithing, mining, and crafting. The etymology of the word dwarf
is contested, and scholars have proposed varying theories about the origins of the being, including that dwarfs may have originated as nature spirits or as beings associated with death, or as a mixture of concepts. Competing etymologies include a basis in the Indo-European root *dheur-
(meaning 'damage'), the Indo-European root *dhreugh
(whence modern German Traum
'dream' and Trug
'deception'), and comparisons have been made with the Old Indian dhvaras
(a type of demonic being). The being may not have gained associations with small stature until a later period.
The terms "dwarf", "little person", "LP", and "person of short stature" are now generally considered acceptable by most people affected by these disorders.
"Midget", whose etymology indicates a "small sandfly," came into prominence in the mid-19th century 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 some 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. 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.
USA dwarfs are supported to compete in sport by the Dwarf Athletic Association of America. There is also the opportunity to take part in international competitions at the Dwarf Games.
In art, literature, or movies, dwarfs are rarely depicted as ordinary 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.
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. Recent scholarship has suggested that ancient Egyptians held dwarfs in high esteem. Several important mythological figures of the North American Wyandot nation are portrayed as dwarfs.
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 Willow
, Austin Powers
, Gulliver's Travels
by Jonathan Swift, The Wizard of Oz
, Willy Wonka & the Chocolate Factory
, A Son of the Circus
, Little People Big World
, The Little Couple
, Harry Potter
, A Song of Ice and Fire
(and its TV adaptation Game of Thrones
, In Bruges
, The Tin Drum
by Günter Grass, the short-lived reality show The Littlest Groom
, 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.
During the Holocaust, dwarfs were often used as medical experimentation subjects at Auschwitz by Josef Mengele. The most notable dwarfs at Auschwitz were the Ovitz family.
Media related to Dwarfism at Wikimedia Commons
Gigantism, also known as giantism (from Greek γίγας gigas, "giant", plural γίγαντες gigantes), is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by over-production of growth hormone in childhood resulting in persons between 7 feet (84 inches) (2.13 m) and 9 feet (108 inches) (2.72 m) in height.
The term is typically applied to those whose height is not just in the upper 1% of the population but several standard deviations above mean for persons of the same sex, age, and ethnic ancestry. The term is seldom applied to those who are simply "tall" or "above average" whose heights appear to be the healthy result of normal genetics and nutrition. Gigantism is usually caused by a tumor on the pituitary gland of the brain. It causes growth of the hands, face, and feet. In some cases the condition can be passed on genetically through a mutated gene.
Other names somewhat obsolete for this pathology are hypersoma (Greek: hyper over the normal level; soma body) and somatomegaly (Greek; soma body, genitive somatos of the body; megas, gen. megalou great). In the past, while many of them were social outcasts because of their height, some (usually unintentionally) found employment in Friedrich Wilhelm I's famous Potsdam Giants regiment.
Many of those who have been identified with gigantism have suffered from multiple health issues involving their circulatory or skeletal system.
Reports of gigantism exist throughout history, with some nations and tribes taller than others.
The giants of Crete are listed in various historic sources, beginning with Titan, a Greek mythological giant, and including Gigantus, after whom giants and gigantism are named. Rhodes is another island where giants were said to have lived, with the Colossus of Rhodes a giant statue of a giant patron god Helios. Goliath, another giant, mentioned in the Bible, was a Philistine warrior who was slain by David in a battle between the Israelites and the Philistines.
Hypersecretion of growth hormone causes gigantism in children and acromegaly in adults. Evaluation of growth hormone hypersecretion cannot be excluded with a single normal GH level due to diurnal variation. However, a random blood sample showing markedly elevated GH is adequate for diagnosis of GH hypersecretion. Additionally, a high-normal GH level that fails to suppress with administration of glucose is also sufficient for a diagnosis of GH hypersecretion.
Insulin-like Growth Factor-1 (IGF-1) is an excellent test for evaluation of GH hypersecretion. It does not undergo diurnal variation and will thus be consistently elevated in GH hypersecretion and therefore patients with gigantism. A single normal IGF-1 value will reliably exclude GH hypersecretion.
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Achondroplasia in children is the most common form of dwarfism; it accounts for about 70% of all cases of dwarfism. Achondroplasia falls into the category of “disproportionate dwarfism”. It is linked to a mutation in the fibroblast growth factor receptor-3. More than 250,000 people in the world are diagnosed with Achondroplasia currently. Achondroplasia diagnosis occurs somewhere between one in every 10,000 to one in every 30,000 live births. Some symptoms of Achondroplasia are short stature, long and narrow trunk, shortening of the proximal segments of limbs, large head, mid-face hypoplasia, and joint hyperextension, among other things. Achondroplasia is defined by central nervous system defects as well as the prior physical symptoms. Average height for an adult man or woman diagnosed with Achondroplasia is about 120 centimeters (47.2 inches), although technically a max of 148 centimeters (58.2 inches) is also considered Achondroplasic. Achondroplasic people typically have a long trunk and smaller upper legs and upper arms. Those diagnosed are of normal intelligence and have the ability to lead independent and productive lives.
A child may be diagnosed with Achondroplasia as early as the fetus stages of pregnancy. Most cases are first identified as early as 26 weeks in the gestational period. 85% of children born with Achondroplasia are born of parents who are average height and are not diagnosed with Achondroplasia. But 75% of all diagnosed children are the end product of an entirely new mutation. If both parents are diagnosed with Achondroplasia, however, there is a higher chance of life-threatening problems. Having a child who is Achondroplasic is almost competely sporadic and the chances of having another child who is also Achondroplasic is no more likely than for anyone else. Having an Achondroplasic child is entirely situational. There are specific ways to raise a child diagnosed with Achondroplasia that will be beneficial to their growth and aging. Achondroplasic children, to be given better chances, must be raised in more special care than children who are not diagnosed with Achondroplasia.
Because achondroplasic children have different genes, their growth cycle should be expected to differ from that of a child who is not diagnosed with Achondroplasia. It is very typical for an Achondroplasic child to snore because of their smaller than average size airways. There is no data that unfailingly states respiratory problems. Studies have been done and even though achondroplasic children have reduced lung volumes, the results do not determine respiratory problems. Children diagnosed with Achondroplasia usually have delayed motor milestones, otitis media, and bowing of the lower legs. Achondroplasic infants and young babies also need to be watched carefully the first few years of infancy for support problems. An infant or child’s hearing and sight needs to be monitored through the years. Along with their development of hearing and sight, their posture will not be guaranteed to develop perfectly to support the child. Achondroplasic children may also encounter a speech impediment in their early years. If a child that is diagnosed is falling behind or lacking in any of these areas, they should be taken in to pediatrics for help to restore the children to where they should be. Both infants and children may have health issues that are related to upper-airway obstruction. Typical for achondroplasic children, as well, is sweating more than is average for children. Achondroplasic children’s diets should be watched very closely because it is easy for children to become obese when they are young. Their diets should be restricted to smaller portions than that of a child who is not diagnosed with Achondroplasia. Gastroesophageal reflux is more common in achondroplasic children as well and should be treated and watched very closely if it furthers already heightened respiratory problems. Most infants diagnosed with Achondroplasia will develop thoracolumbar kyphosis, which will need to be treated delicately so they can develop good posture with much care. If not watched properly or treated carefully, thoracolumbar kyphosis can help lead to spinal stenosis.
Achondroplasic children require special attention as they grow up and age. The home setting for an achondroplasic child should be modified in a way that is fitting for a child with a growth mutation. Toys should be considered and altered to fit the needs of the child, or size of the child, such as tricycles and backyard playground equipment. Other fixtures in the home should be replaced to attainable heights for the children such as light switches or door knobs. Because achondroplasic children tend to have weaker posture, supporting cushions should be considered in use as well as stools for their feet when they are sitting down. For an achondroplasic child to develop better, activities such as biking or swimming should be included in their daily schedule. These activities may help with strength in the limbs and posture and will help to avert the problems of thoracolumbar kyphosis and spinal stenosis. Other activities, like gymnastics or rough sports should be avoided because they will help with the deteriorating of their back support and posture. Achondroplasic children should also be worked with daily on their verbal skills, so as to help them overcome the speech impediments they may likely encounter.
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EDAR (EDAR Hypohidrotic ectodermal dysplasia)
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals over a number of generations when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf breeds, called dwarfing. This process has occurred many times throughout evolutionary history, with examples including dinosaurs, like Europasaurus, and modern animals such as elephants and their relatives. This process, and other "island genetics" artifacts, can occur not only on traditional islands, but also in other situations where an ecosystem is isolated from external resources and breeding. This can include caves, desert oases, isolated valleys and isolated mountains ("sky islands"). Insular dwarfism is one aspect of the more general "island rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bodies, and large species tend to evolve smaller bodies.
There are several proposed explanations for the mechanism which produces such dwarfism.
One is a selective process where only smaller animals trapped on the island survive, as food periodically declines to a borderline level. The smaller animals need fewer resources and smaller territories, and so are more likely to get past the break-point where population decline allows food sources to replenish enough for the survivors to flourish. Smaller size is also advantageous from a reproductive standpoint, as it entails shorter gestation periods and generation times.
In the tropics, small size should make thermoregulation easier.
Among herbivores, large size confers advantages in coping with both competitors and predators, so a reduction or absence of either would facilitate dwarfing; competition appears to be the more important factor.
Among carnivores, the main factor is thought to be the size and availability of prey resources, and competition is believed to be less important. In tiger snakes, insular dwarfism occurs on islands where available prey is restricted to smaller sizes than are normally taken by mainland snakes. Since prey size preference in snakes is generally proportional to body size, small snakes may be better adapted to take small prey.
The inverse process, wherein small animals breeding on isolated islands lacking the predators of large land masses may become much larger than normal, is called island gigantism. An excellent example is the dodo, the ancestors of which were normal-sized pigeons. There are also several species of giant rats, one still extant, that coexisted with both Homo floresiensis and the dwarf stegodons on Flores.
The process of insular dwarfing can occur relatively rapidly by evolutionary standards. This is in contrast to increases in maximum body size, which are much more gradual. When normalized to generation length, the maximum rate of body mass decrease during insular dwarfing was found to be over 30 times greater than the maximum rate of body mass increase for a ten-fold change in mammals. The disparity is thought to reflect the fact that pedomorphism offers a relatively easy route to evolve smaller adult body size; on the other hand, the evolution of larger maximum body size is likely to be interrupted by the emergence of a series of constraints that must be overcome by evolutionary innovations before the process can continue.
For both herbivores and carnivores, island size, the degree of island isolation and the size of the ancestral continental species appear not to be of major direct importance to the degree of dwarfing. However, when considering only the body masses of recent top herbivores and carnivores, and including data from both continental and island land masses, the body masses of the largest species in a land mass were found to scale to the size of the land mass, with slopes of about 0.5 log(body mass/kg) per log(land area/km2). There were separate regression lines for endothermic top predators, ectothermic top predators, endothermic top herbivores and (on the basis of limited data) ectothermic top herbivores, such that food intake was 7 to 24-fold higher for top herbivores than for top predators, and about the same for endotherms and ectotherms of the same trophic level (this leads to ectotherms being 5 to 16 times heavier than corresponding endotherms).
Among the most famous examples of insular dwarfism are:
Midget (from midge, a sand fly) is a term that is widely considered pejorative for a person of unusually short stature, often one with the medical condition dwarfism, particularly proportionate dwarfism.
When applied as an adjective, it can also refer to anything of much smaller than normal size, as a synonym for "miniature," or to sports leagues, such as hockey, for young players.
Merriam-Webster dictionary states that the first use of the term "midget" was in 1816. The term "midget" came into prominence in the mid-19th century 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. P. T. Barnum indirectly helped popularize the term "midget" when he began featuring General Tom Thumb in his circus. "Midget" became linked to referencing short people put on public display for curiosity and sport.
Such performances continued to be widespread through the mid part of the twentieth century, with Hermines Midgets brought from their performances in Paris to appear at the 1939 New York World's Fair. When interviewed for a 1999 piece, performers engaged in ongoing "Midget Wrestling" events stated that they did not view the term "Midget Wrestling" as derogatory, but merely descriptive of their small size; however, others responding to the piece disagreed, with one stating that the performances perpetuated an outdated and demeaning image.