What Is Dwarfism?

Here are some facts that people may not know about dwarfism.

• Dwarfism is characterized by short stature caused by changes in bone and cartilage growth.
• According to Little People of America (LPA), an advocacy group for people with dwarfism and their families, individuals with dwarfism reach a final height of 4 feet 10 inches or shorter.
• Most often, people with dwarfism are born to average-height parents.
• The most common type of dwarfism is achondroplasia (pronounced: ay-kon-dreh-PLAY-zyuh).
• Most people with dwarfism have typical intelligence.
• Dwarfism is not a disease that requires a "cure." Just like their average-height peers, people with dwarfism go to college, drive cars, find meaningful jobs, get married, and have children.

What Causes Dwarfism?

There are over 700 different forms of skeletal dysplasia caused by genetic changes (mutations) that affect bone and cartilage growth. Many of these conditions result in short stature or dwarfism. Most often, genetic changes associated with various forms of dwarfism happen randomly, either before pregnancy (in the sperm or egg) or at the start of pregnancy (conception). Sometimes, dwarfism happens because a child inherited a genetic change(s) from one or both parents There is nothing a parent could do before or during pregnancy to prevent this change.

What Are the Types of Dwarfism?

In general, dwarfism is caused by a skeletal dysplasia that results in disproportionate short stature. This means that the limbs (arms and legs) and the trunk are not of the same proportion as they are in people of average height.

The two types of this disproportion are short-trunk and short-limb:

• Short-trunk dwarfism: The torso is shortened when compared with the arms and legs.
• Short-limb dwarfism: The arms and legs appear shortened when compared with the trunk.

Achondroplasia is the most common form of dwarfism. It happens in about 1 in 25,000 people of all races and ethnic groups. People with achondroplasia have a relatively long trunk and shortened arms and legs. This is most noticeable in the upper parts of their arms and legs (called rhizomelic shortening).

Other common features can include:

• a larger head with a prominent forehead
• a flattened bridge of the nose
• shortened hands and fingers
• a sway of the lower back
• bowed legs

The average adult height for someone with achondroplasia is around 4 feet tall.

Diastrophic dysplasia is another form of short-limb dwarfism. It happens in about 1 in 100,000 births. Shortening is most noticeable in the bones in the lower parts of the arms and legs (called mesomelic shortening).

Other common features can include:

• cleft palate
• changes in the outer ear (also known as a cauliflower-like appearance)
• differences in thumb position (also called hitchhiker thumbs)
• clubfeet (inward or downward pointing feet)
• curves in the spine that can change over time

Most people with diastrophic dysplasia have joint changes that limit movement. People with diastrophic dysplasia often benefit from mobility aids, such as crutches, a scooter, or a wheelchair to get around.

Spondyloepiphyseal dysplasias (SED) are short-trunk skeletal dysplasias that involve the spine and the end of the bones that make up the joints (epiphyses). In one type of SED, the short trunk may not be noticed until the child is school age. Other types are seen at birth.

Other common features can include:

• clubfeet
• cleft palate
• vision and/or hearing differences
• instability of the spine and/or curves in the spine that change over time
• reduced joint mobility and arthritis early in life

How Is Dwarfism Diagnosed?

Most pregnant women have a prenatal ultrasound to measure the baby's growth at around 20 weeks. At that stage, features of achondroplasia aren't yet noticeable. Doctors sometimes suspect achondroplasia before birth if an ultrasound late in a pregnancy shows that a baby's arms and legs are shorter than average and the head is larger. But many children with achondroplasia aren't diagnosed until after birth.

Doctors can recognize some other types of skeletal dysplasia earlier in pregnancy. Others aren't noticed until the first few months or years of life, when a child's growth slows. A health care provider may take X-rays after birth to check for bone changes. Doctors also may use genetic testing before or after birth to confirm the diagnosis.

Possible Problems and Treatments

Each condition that causes dwarfism has its own possible medical problems, which can change over time.

Individuals with dwarfism may get care from doctors who specialize in orthopedics, genetics/skeletal dysplasias, neurosurgery, ENT, and pulmonology. Some medical concerns require surgery.

People with dwarfism should try to keep a healthy weight. A few extra pounds can put harmful stress on the back and joints.

What Else Should I Know?

People with dwarfism can lead healthy, active lives. The Americans with Disabilities Act protects their rights.

Types of skeletal dysplasia and the severity of medical needs vary from person to person. In general, with proper medical care, life span is not affected by having dwarfism.