Dwarfism

Overview

Dwarfism is short stature that results from a genetic or medical condition. Stature is the height of a person in a standing position. Dwarfism generally is defined as an adult height of 4 feet, 10 inches (147 cm) or less. The average adult height among people with dwarfism is 4 feet, 1 inch (125 cm) for women and 4 feet, 4 inches (132 cm) for men.

Many medical conditions cause dwarfism. In general, dwarfism is divided into two broad categories:

• Disproportionate dwarfism. This is when some parts of the body are small, and others are of average or above-average size. Conditions causing this category of dwarfism get in the way of bone development.
• Proportionate dwarfism. This is when all parts of the body are small to the same degree and appear like a body of average stature. Medical conditions present at birth or that occur in early childhood limit overall growth and development.

Some people prefer the term "short stature" or "little people" rather than "dwarf" or "dwarfism." It's important to be sensitive to the preference of someone who has this condition. Short stature conditions don't include familial short stature — short height that's thought of as a typical variation with typical bone development.

Symptoms

Symptoms — other than short stature — vary greatly across the range of dwarfism conditions.

Disproportionate dwarfism

Most people with dwarfism have conditions that cause short stature with body parts that aren't the same size as one another. Usually, this means that a person has an average-sized trunk and very short limbs. But some people may have a very short trunk and short limbs. Those limbs are larger than the rest of the body. In these people, the head is large compared with the body.

Almost all people with disproportionate dwarfism have average intelligence. Rare exceptions are usually due to a secondary factor, such as excess fluid around the brain. This also is known as hydrocephalus.

The most common cause of dwarfism is a condition called achondroplasia, which causes disproportionately short stature. This condition usually results in:

• An average-sized 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 large head in relation to the rest of the body, with a prominent forehead and a flattened bridge of the nose.
• Bowed legs that get worse.
• Swayed lower back that gets worse.
• An adult height of 4 feet, 1 inch (125 cm) for women and 4 feet 4 inches (132 cm) for men.

Another cause of disproportionate dwarfism is a rare condition called spondyloepiphyseal dysplasia congenita (SEDC).

Signs may include:

• A very short trunk.
• A short neck.
• Shortened arms and legs.
• Average-sized hands and feet.
• A broad, rounded chest.
• Slightly flattened cheekbones.
• An opening in the roof of the mouth, also called a cleft palate.
• Changes in hip structure that result in thighbones turning inward.
• A foot that's twisted or out of shape.
• Neck bones that are not stable.
• Hunching curvature of the upper spine that gets worse over time.
• Swayed lower back that gets worse over time.
• Vision and hearing problems.
• Arthritis and problems moving joints.
• 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 that occur in early childhood that limit overall growth and development. The head, trunk and limbs are all small, but they're small to the same degree. Because these conditions affect overall growth, poor development of one or more body systems is possible.

Growth hormone deficiency is a fairly common cause of proportionate dwarfism. It occurs when the pituitary gland doesn't make enough growth hormone. This hormone is needed for typical 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.

When to see a doctor

Symptoms of disproportionate dwarfism often are present at birth or in early infancy. Proportionate dwarfism may not be seen at first. See your child's healthcare professional if you are worried about your child's growth or overall development.

Causes

Most often dwarfism is caused by gene changes, also called genetic variants. In many children, it's due to a random change in a child's gene. But dwarfism also can be inherited due to a genetic variant in one or both parents. Other causes can include low levels of hormones and poor nutrition. Sometimes the cause of dwarfism is not known.

Achondroplasia

About 80% of people with achondroplasia are born to parents of average height. A person with achondroplasia who had two average-sized parents received one changed gene related to the condition and one regular gene. A person with achondroplasia may pass along a changed gene related to the condition or a regular gene to their children.

Turner syndrome

Turner syndrome, a condition that affects only female children, results when a sex chromosome — the X chromosome — is missing or partially missing. A female child 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.

Low levels of growth hormones

Sometimes low levels of growth hormones can be traced to a genetic change or injury. But for most people with low hormone levels, no cause is found.

Other causes

Other causes of dwarfism include other genetic conditions, low levels of other hormones, or poor nutrition. Sometimes the cause is not known.

Risk factors

Risk factors depend on the type of dwarfism. In many cases, a gene change related to dwarfism happens at random and is not passed from parent to child. If one or both parents have dwarfism, the risk of having a child with dwarfism rises.

If you want to become pregnant and need to understand the chances of your child having dwarfism, talk with your healthcare professional about getting genetic testing. Also ask about other risk factors.

Complications

Complications of dwarfism-related conditions can vary greatly, but some complications are common to several conditions.

Disproportionate dwarfism

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

• Delays in developing motor skills, such as sitting up, crawling and walking.
• Ear infections that occur a lot and risk of hearing loss.
• Bowing of the legs.
• A hard time breathing while sleeping, also known as sleep apnea.
• Pressure on the spinal cord at the base of the skull.
• Extra fluid around the brain, also known as hydrocephalus.
• Need for dental work.
• Serious hunching or swaying of the back with back pain or problems breathing that get worse.
• Narrowing of the channel in the lower spine that puts pressure on the spinal cord and leads to pain or numbness in the legs. This is called spinal stenosis.
• Arthritis.
• Weight gain that can complicate joint and spine conditions and place pressure on nerves.

Proportionate dwarfism

With proportionate dwarfism, problems in growth and development often lead to complications with organs that don't grow properly. For example, heart conditions that often occur with Turner syndrome can affect health greatly. An absence of sexual maturation related to having low growth hormone levels or Turner syndrome can affect physical development and social functioning.

Pregnancy

Women with disproportionate dwarfism may have respiratory problems during pregnancy. A C-section is almost always needed 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. But some people may refer to themselves as "dwarfs," "little people" or "people of short stature."

People of average height may have misconceptions about people with dwarfism. And the portrayal of people with dwarfism in modern movies often includes stereotypes. Misconceptions can affect a person's self-esteem and limit how well they do at school or work.

Children with dwarfism often are teased and mocked by classmates. Because dwarfism is relatively uncommon, children may feel like they're on their own. They may need mental health and peer support for the best quality of life.