Definition

Achondroplasia (ACH) is a genetic bone disorder. It is the most common type of dwarfism. Key features are a large head, short limbs, a narrow chest, and short fingers.

Causes

Causes may be:

• Changes in the FGFR3 gene
• Advanced age of father

Risk Factors

This problem can happen in people who do not have any known risk factors.

The gene changes can also be passed through a family, though this is not as common.

Symptoms

Problems are often seen at birth. Key features are a large head, short limbs, a narrow chest, and short fingers.

Other problems may be:

• Short stature—adult height will be 4 to 4½ feet
• Bowlegs
• Short toes
• Underdeveloped parts of the face
• Arms that may not be fully straight at the elbow
• An excessive lower back curve

Diagnosis

A prenatal ultrasound may point to ACH. Genetic testing may be done to confirm it.

ACH may also be suspected during a physical exam at birth. It can be confirmed through x-rays. Rarely, genetic testing may be done if the exam and x-rays are not certain.

Treatment

There is no cure. The goal of treatment is to manage related health problems. Choices are:

• Medicine, such as human growth hormone to increase adult height
• Surgery to treat health problems, such as:
  • Spinal fusion to connect spinal bones to make them more stable
  • Laminectomy to remove parts of spinal bones to ease pressure on the spinal cord
  • Osteotomy to repair severe bowlegs
  • Bone lengthening to cut and divide a bone to encourage more growth
• Counseling and support groups

Prevention

There are no known guidelines to prevent ACH.