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Achondrogenesis Type I
Monday, 26 January 2004
Thursday, 18 November 2004
Type 1B, Lethal Achondrogenesis, Parenti-Fraccaro Type


Achondrogenesis Type I is a problem in the development of bone and cartilage. The result is a collection of physical symptoms related to the bone abnormalities, including abnormal short stature with short limbs, barrel chest, and a large head for the size of the body. The cause of the problem is genetic and therefore, this condition is inherited within families. At least two types of Achondrogenesis exist. Both are similar, but are caused by different genes. The naming of these disorders is confusing and controversial, though some of this is being resolved as better information about the disorders becomes available.


Achondrogenesis Type I is inherited in an autosomal recessive manner. Males and females are equally affected and there is no increased risk associated with race. Autosomal recessive inheritance means that the genes causing the condition are present in the child who inherits two copies of the affected gene carrying the disease. In most situations, one affected gene comes from the mother and one from the father. Each parent may be unaware that he/she carries a gene with the disease because the they each have another normal gene that counter balances the affected gene. The disease needs two copies of the disease gene in any one individual to show any physical signs or symptoms.

Signs and Symptoms

Most newborns with the condition will show some or all of the following:

  • Low birth weight (1200 grams or less)
  • Head seems disproportionately large
  • Narrow chest
  • Extremely short limbs and neck
  • Breathing problems
  • Some heart defects

Possible Causes

Achondrongensis Type I is caused by a change in a gene on chromosome 5 called the diastrophic dysplasia sulfate transporter, or DTDST gene. There is more then one possible way for the gene to change into the malfunctioning form that causes disease, and there is a related disease (diastrophic dysplasia) caused by different changes in this gene. When this transporter is malfunctioning, sulfate (a necessary component of bone and cartilage) is not properly incorporated into the growing bone and/or cartilage.


If Achondrogenesis Type I is suspected, the only way to absolutely confirm the disease is to conduct DNA tests and identify the DTDST gene in the changed form. Prenatal diagnosis is available by genetic testing and ultrasound imaging testing.


There is no current treatment for the condition of Achondrogenesis Type I. Supportive care is provided for the newborn depending on the particular signs and symptoms the baby might have as listed above. Research in genetics is constantly providing new information and some day may provide more information on the treatment and prevention of the disease. Genetic counseling is available to determine a couples’ risk of having future offspring with the condition.


The exact prognosis for a given newborn will vary depending on the severity of his/her symptoms. However, Achondrogenesis Type 1B is usually fatal in the first months of life because of the abnormal skeleton, and many children are stillborn.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Very nice, informative site from the National Institutes of Health.
This is the official website for the Little People of America, an organization that offers information and support to patients with dwarfism due to any cause.

Google Search for Achondrogenesis Type I

References and Sources

Online Medical Dictionary. Online Mendelian Inheritance of Man. “Achondrogenesis” MedLine Plus. Chen, Harold. “Achondrogenesis”