INTRODUCTION
Dwarfism is a condition of short stature. It is a growth disorder characterized by shorter than average body height. Dwarfism is considered as a disability in many countries including the USA (under Americans with Disabilities Act), India (under Rights of Persons with Disabilities Act) and South Africa.
Human beings with adult body height less than 4 feet 10 inches (147.32cm) are considered to be affected with dwarfism. The average height of dwarfism affected adult persons is 4 feet (122 cm).
Depending on the type of dwarfism a person’s body is either disproportionate or proportionate. Dwarfs whose bodies are disproportionate have a torso of average size but short arms and legs, this is apparent in conditions such as, Achondroplasia. Dwarfs who are proportionate appear only to be small in stature, their arms, legs, trunk and head are in the same proportion as an average size person, only small and they can also have underlying medical conditions.
TYPES OF DWARFISM
1. Proportionate
2. Disproportionate (also known as skeletal dysplasias)
1. Achondroplasia
2. Spondyloepiphyseal dysplasias
3. Diastrophic dysplasia
Proportionate dwarfism results from medical conditions present at birth or appearing in early childhood that limit overall growth and development. So the head, trunk and limbs are all small, but they're proportionate to each other. Because these disorders affect overall growth, many of them result in poor development of one or more body systems.
Growth hormone deficiency is a relatively common cause of proportionate dwarfism. It occurs when the pituitary gland fails to produce an adequate supply of growth hormone, which is essential for normal childhood growth. Signs include:
· Height below the third percentile on standard pediatric growth charts
· Growth rate slower than expected for age
· Delayed or no sexual development during the teen years
Most people with dwarfism have disorders that cause disproportionately short stature. Usually, this means that a person has an average-size trunk and very short limbs, but some people may have a very short trunk and shortened (but disproportionately large) limbs. In these disorders, the head is disproportionately large compared with the body.
Almost all people with disproportionate dwarfism have normal intellectual capacities. Rare exceptions are usually the result of a secondary factor, such as excess fluid around the brain (hydrocephalus).
Occurrence: 1 in 40,000 babies, the most common form of dwarfism.
Characterized by long trunk and shortened upper parts of arms and legs.
· An average-size trunk
· Short arms and legs, with particularly short upper arms and upper legs
· Short fingers, often with a wide separation between the middle and ring fingers
· Limited mobility at the elbows
· A disproportionately large head, with a prominent forehead and a flattened bridge of the nose
· Progressive development of bowed legs
· Progressive development of swayed lower back
· An adult height around 4 feet (122 cm)
Occurrence: 1 in 95,000 babies.
Characterized by a shortened trunk.
· A very short trunk
· A short neck
· Shortened arms and legs
· Average-size hands and feet
· Broad, rounded chest
· Slightly flattened cheekbones
· Opening in the roof of the mouth (cleft palate)
· Hip deformities that result in thighbones turning inward
· A foot that's twisted or out of shape
· Instability of the neck bones
· Progressive hunching curvature of the upper spine
· Progressive development of swayed lower back
· Vision and hearing problems
· Arthritis and problems with joint movement
· Adult height ranging from 3 feet (91 cm) to just over 4 feet (122 cm)
Occurrence: 1 in 100,000 babies.
Characterized by shortened forearms and calves.
CAUSES OF DWARFISM
Most dwarfism-related conditions are genetic disorders, but the causes of some disorders are unknown. Most occurrences of dwarfism result from a random genetic mutation in either the father's sperm or the mother's egg rather than from either parent's complete genetic makeup.
Achondroplasia
About 80 percent of people with achondroplasia are born to parents of average height. A person with achondroplasia and with two average-size parents received one mutated copy of the gene associated with the disorder and one normal copy of the gene. A person with the disorder may pass along either a mutated or normal copy to his or her own children.
Turner syndrome
Turner syndrome, a condition that affects only girls and women, results when a sex chromosome (the X chromosome) is missing or partially missing. A female inherits an X chromosome from each parent. A girl with Turner syndrome has only one fully functioning copy of the female sex chromosome rather than two.
Growth hormone deficiency
The cause of growth hormone deficiency can sometimes be traced to a genetic mutation or injury, but for most people with the disorder, no cause can be identified.
Other causes
Other causes of dwarfism include other genetic disorders, deficiencies in other hormones or poor nutrition. Sometimes the cause is unknown.
Skeletal dysplasia is caused by a genetic mutation. The gene mutation can occur spontaneously or can be inherited.
Diastrophic dysplasia and usually spondyloepiphyseal dysplasias are inherited in a recessive manner. This means a child must receive two copies of the mutated gene -- one from the mother, one from the father -- to be affected.
Achondroplasia, on the other hand, is inherited in a dominant manner. That means a child needs only one copy of the mutated gene to have that form of skeletal dysplasia. There is a 25% chance that a child born to a couple in which both members have achondroplasia will be of normal height. But there is also a 25% chance the child will inherit both dwarfism genes, a condition known as double-dominant syndrome. This is a fatal condition that usually results in miscarriage.
Often parents of children with achondroplasia do not carry the mutated gene themselves. The mutation in the child occurs spontaneously at the time of conception.
Doctors do not know what causes a gene to mutate. It is a seemingly random occurrence that can happen in any pregnancy. When average-size parents have a child with dwarfism due to a spontaneous mutation, it is not likely that other children will also have the mutation.
In addition to genetic skeletal dysplasia, short stature has other causes, including disorders of the pituitary, which influence growth and metabolism; kidney disease; and problems that affect the body's ability to absorb nutrients.
Some forms of dwarfism are evident in utero, at birth or during infancy and can be diagnosed through X-rays and a physical exam. A diagnosis of achondroplasia, diastrophic dysplasia, or spondyloepiphyseal dysplasia can be confirmed through genetic testing. In some cases, prenatal testing is done if there is concern for specific conditions.
Sometimes dwarfism doesn't become evident until later in a child's life, when dwarfism signs lead parents to seek a diagnosis. Here are signs and symptoms to look for in children that indicate a potential for dwarfism:
Early diagnosis and treatment can help prevent or lessen some of the problems associated with dwarfism. People with dwarfism related to growth hormone deficiency can be treated with growth hormone.
In many cases, people with dwarfism have orthopaedic or medical complications. Treatment of those can include:
Other treatment may include: