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Genetic and Rare Diseases Information Center (GARD)

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Axial spondylometaphyseal dysplasia


Other Names for this Disease

  • Axial SMD
  • SMD Axial
  • Spondylometaphyseal dysplasia axial type
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

In laymans terms, What is it? How does a child get it? What are the genetic factors involved? What can we expect from future generations? Is growth hormone therapy, surgery, or visual corrections available? How does this condition affect a person over the course of their life? What can be done to treat it?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is axial spondylometaphyseal dysplasia?

Axial spondylometaphyseal dysplasia is a genetic disorder of bone growth. The term “axial” means towards the center of the body. “Sphondylos” is a Greek term meaning vertebra. “Metaphyseal dysplasia” refers to abnormalities at the ends of long bones. Axial spondylometaphyseal dysplasia primarily affects the bones of the chest, pelvis, spine, upper arms and upper legs, and results in shortened stature. For reasons not well understood, this rare skeletal dysplasia is also associated with early and progressive vision loss. The underlying genetic cause of axial spondylometaphyseal dysplasia is currently unknown. It is thought to be inherited in an autosomal recessive fashion.[1]
Last updated: 9/14/2012

What are the signs and symptoms of axial spondylometaphyseal dysplasia? How does it affect a person overtime?

Common signs and sympotms of axial spondylometaphyseal dysplasia, include short stature, chest, spine, limb, and pelvic bone changes, and vision disturbance.[1]

People with axial spondylometaphyseal dysplasia may have a normal birth length, but demonstrate growth failure by late infancy to early childhood. A measurement called standard deviation (SD) is used to compare the height of different children. If a child's height is more than 2 SD's below the average height of other children the same age, the child is said to have short stature. This means that almost all of the other children that age (more than 95% or 19 out of 20) are taller.[2] Individual case reports of children and an adult with axial spondlometaphyseal dysplasia demonstrate height as being between 2 to 6 SD’s below average.[1]

Infants with axial spondlometaphyseal dysplasia tend to have a shortened chest with short ribs, a condition called thoracic hypoplasia. Thoracic hypoplasia tends to become more prominent in childhood, and less noticeable in adolescence and adulthood. Thoracic hypoplasia may cause mild to moderate breathing problems in infants and recurring lung infections in childhood.[1]

Young children with axial spondlometaphyseal dysplasia have shortened upper arms and upper leg bones, which may become less prominent as they grow.[1]

Spine changes include vertebrae that have a flattened appearance on x-ray. This finding is typically mild in infancy and early childhood, becomes more apparent in late childhood, then self-corrects by adulthood. Some individuals with axial spondylometaphyseal dysplasia develop scoliosis (curvature of the spine).[1]

Pelvic bone changes can be seen in infants and children. Some of these changes self-correct by adulthood.[1] A condition called “coxa vara” (where the angle between the top of the femur and the femoral shaft is smaller than normal) is common beginning in late childhood and persists through adulthood.[1] Coxa vara may affect gait (pattern or way of walking). Some people with axial spondlometaphyseal dysplasia have minor bone changes in their knees.[1]

Vision problems, including retinitis pigmentosa and/or optic atrophy, become evident in infancy or early childhood and rapidly worsen.[1] Retinitis pigmentosa causes cells in the retina to breakdown and die, eventually resulting in vision loss. Optic atrophy causes vision to dim and reduces the field of vision. It also reduces the ability to see fine detail and color (ie., colors will seem faded). With the progression of optic atrophy, a person's pupil reaction to light diminishes and may eventually be lost. Long term outlook for vision for people with axial spondylometaphyseal dysplasia is poor.[1]

Last updated: 9/14/2012

How does a child get axial spondylometaphyseal dysplasia? What are the genetic factors involved?

Axial spondylometaphyseal dysplasia is thought to be a genetic disorder, however the underlying genetic cause is not known.[1]
Last updated: 9/14/2012

How is axial spondylometaphyseal dysplasia passed through families?

An autosomal recessive pattern of inheritance is suspected in axial spondylometaphyseal dysplasia. You can learn more about autosomal recessive inheritance at the following links:

MedlinePlus.gov: http://www.nlm.nih.gov/medlineplus/ency/article/002052.htm
Genetic Home Reference:  http://ghr.nlm.nih.gov/handbook/illustrations/autorecessive

To learn more about your family's specific risks, we recommend that you speak with a genetics professional. Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference at http://ghr.nlm.nih.gov/handbook/consult. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 9/14/2012

How might axial spondylometaphyseal dysplasia be treated? Is growth hormone therapy an option? Is surgery helpful? Can the vision problems be corrected?

There is no specific treatment for axial spondylometaphyseal dysplasia. Symptoms such as lung infections, breathing difficulties, coxa vara, scoliosis, retinitis pigmentosa, and optic atrophy are managed individually. Specialists such as opthmologists, geneticists, and orthopedists work in concert in devloping an individualized treatment plan. We are unaware of any cases describing the use of growth hormone therapies for treatment of short stature caused by axial spondylometaphyseal dysplasia. Treatment of skeletal dysplasias with growth hormone therapy must be done with caution. 

The Little People of America, Inc Web site lists articles on repiratory and breathing problems in people with skeletal dysplasias, including an article titled Breathing Problems Among Little People: When to Be Concerned.

Detailed information related to the management of retinitis pigmentosa can be accessed through GeneReviews and the Treatment and Medication sections of Medscape Reference.

Detailed information related to the management of coxa vara can also be found in the Treatment sections of a Medscape Reference review article on this condition.

Johns Hopkins Department of Orthopedic Surgery offers a Patient Guide to Scoliosis.

MedlinePlus.gov provides information on optic atrophy

Further medical support resources can be found through the Little People of America, Inc.
Last updated: 9/14/2012

References
Other Names for this Disease
  • Axial SMD
  • SMD Axial
  • Spondylometaphyseal dysplasia axial type
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.