DWARFISM

Definition

Dwarfism is short stature that results from a genetic or medical condition. Dwarfism is generally defined as an adult height of 4 feet 10 inches or less (147 centimeters). The typical range in adult height among people with dwarfism is 2 feet 8 inches (81 centimeters) to 4 feet 8 inches (142 centimeters).

Treatments for most dwarfism-related conditions don't increase stature but may lessen complications.

Many people with dwarfism encounter discrimination. Family support, social networks, advocacy groups and adaptive products enable most people with dwarfism to address challenges in educational, work and social settings.

Symptoms

More than 200 different medical conditions cause dwarfism. Therefore, dwarfism symptoms — other than short stature — vary considerably across the spectrum of disorders. In general, the disorders are divided into two broad categories:

  • Disproportionate dwarfism. If body size is disproportionate, some parts of the body are small, and others are of average size or above-average size. Disorders causing disproportionate dwarfism inhibit the development of bones.
  • Proportionate dwarfism. A body is proportionately small if all parts of the body are small to the same degree and appear to be proportioned like a body of average stature.

Disproportionate dwarfism

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. The other common characteristic of these disorders is the head being disproportionately larger than 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).

About 70 percent of all people with dwarfism have a disorder called achondroplasia, which causes disproportionately short stature. This disorder usually results in:

  • 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 flattened bridge of the nose
  • Progressive development of bowed legs (genu varum)
  • Progressive development of swayed lower back (lordosis)
  • An adult height around 4 feet — about 122 centimeters (cm)

A disorder called spondyloepiphyseal dysplasia congenita (SEDC), while rare, is the most common cause of disproportionate dwarfism with a short trunk. Signs may include:

  • A very short trunk, which may or may not be apparent in infancy
  • A short neck
  • Shortened arms and legs
  • Average-size hands and feet
  • Slightly flattened cheekbones
  • Hip deformities that result in thighbones turning inward (coxa vara)
  • Feet twisted or out of shape (clubfoot)
  • Progressive hunching curvature of the upper spine (kyphosis)
  • Progressive development of lordosis
  • Vision and hearing problems
  • Adult height ranging from 3 feet (91 cm) to just over 4 feet (122 cm)

Proportionate dwarfism

Proportionate dwarfism results from medical conditions present at birth or during early childhood that limit overall growth and development. Therefore, the head, trunk and limbs are all small but of average proportions relative to each other.

Most of these disorders are uncommon, and signs and symptoms of the disorders vary greatly. Because these disorders affect overall growth, many of them result in poor development of one or more body systems. A few disorders causing proportionate dwarfism result in mental retardation.

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 regular 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 adolescence

Turner syndrome, also relatively common, is a disorder that results in short stature and impaired sexual maturation in females. Some signs and symptoms may be apparent at birth or early in infancy, but delays in expected growth during childhood or sexual maturation during adolescence may be the first signs. Signs of the disorder may include:

  • Wide or web-like neck
  • Receding or small lower jaw
  • High, narrow roof of the mouth (palate)
  • Low hairline at the back of the head
  • Broad chest with widely spaced nipples
  • Short hands
  • Arms that turn outward at the elbows (cubitus valgus)
  • Swelling of the hands and feet, especially at birth
  • Delayed growth
  • Delayed sexual maturation

When to see a doctor

Signs and symptoms of disproportionate dwarfism are often present at birth or early in infancy. Proportionate dwarfism may not be immediately apparent. See your child's doctor if you have any concerns about your child's growth or overall development.

Causes

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 being in one of the 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 occurs because of a random deletion or severe alteration of an X chromosome, either in the sperm or egg. (The X chromosome is one of two chromosomes that determine the sex of a person. A female inherits an X chromosome from each parent, and a male inherits a Y chromosome from his father and an X chromosome from his mother.) 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 of dwarfism include deficiencies in other hormones and poor nutrition.

Complications

Complications of dwarfism-related disorders can vary greatly, but some complications are common among a number of conditions.

Disproportionate dwarfism

The characteristic features of the skull, spine and limbs shared by most forms of disproportionate dwarfism result in some common problems:

  • Delays in motor skills development, such as sitting up, crawling and walking
  • Frequent ear infections (otitis media) and risk of hearing loss
  • Bowing of the legs (genu varum)
  • Difficulty breathing during sleep (sleep apnea)
  • Pressure on the spinal cord at the base of the skull
  • Excess fluid around the brain (hydrocephalus)
  • Crowded teeth
  • Progressive severe hunching (kyphosis) or swaying (lordosis) of the back
  • In adulthood, narrowing of the channel in the lower spine (lumbosacral spinal stenosis), resulting in pressure on the spinal cord and subsequent pain or numbness in the legs
  • Arthritis in adulthood
  • Weight gain that can further complicate problems with joints and the spine and place pressure on nerves

Proportionate dwarfism

With disorders causing proportionate dwarfism, problems in overall growth often result in complications with other poorly developed organs. For example, heart problems often present in Turner syndrome can have a significant effect on a child's general health. An absence of sexual maturation associated with growth hormone deficiency or Turner syndrome affects not only physical development but also social functioning.

Pregnancy
Women with disproportionate dwarfism may develop respiratory problems during pregnancy. A cesarean delivery is almost always necessary because the size and shape of the pelvis doesn't allow for successful vaginal delivery.

Public perceptions

Most people with dwarfism prefer not to be labeled by a condition. However, some people may refer to themselves as dwarfs or little people. The word "midget" is considered a derogatory term.

People of average height often hold misconceptions about people with dwarfism. Many wrongly believe that people with dwarfism have limited intellectual abilities or personality disorders. Judging maturity by height rather than age, some people may treat people with dwarfism as children.

There's also a long history of people with dwarfism being treated as spectacles for entertainment. And the portrayal of people with dwarfism in modern movies often resorts to stereotypes.

Children with dwarfism are particularly vulnerable to teasing and ridicule from classmates. Because dwarfism is relatively uncommon, children may feel isolated from their peers.

Coping and support

If your child has dwarfism, you can take a number of steps to help him or her cope with challenges and function independently:

Seek help. The nonprofit organization Little People of Uganda provides people with dwarfism and their families social support, information about disorders, advocacy opportunities and resources.

Modify your home. Make changes to your home, such as putting specially designed extensions on light switches, installing lower handrails in stairways and replacing doorknobs with levers. The Little People of America Web site provides links to companies that sell adaptive products, such as size-appropriate furniture and everyday household tools.

Talk to educators. Talk to school personnel about what dwarfism is, how it affects your child, what needs your child may have in the classroom and how the school can help meet those needs.

Talk about teasing. Encourage your child to talk to you about his or her feelings, and practice responses to insensitive questions and teasing.

Reference: Mayo Clinic -