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 that 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).

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

  • 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 (genu varum)
  • Progressive development of swayed lower back (lordosis)
  • An adult height around 4 feet — about 122 cm

Another cause of disproportionate dwarfism is a rare disorder called spondyloepiphyseal dysplasia congenita (SEDC). 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)
  • A foot that's 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 appearing in early childhood that limit overall growth and development. Therefore, the head, trunk and limbs are all small, but they are 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 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

When to see a doctor

Signs and symptoms of disproportionate dwarfism are often present at birth or in early 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.

Aug. 27, 2011