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Genetic and Rare Diseases Information Center (GARD)

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Your Question

What testing is available to distinguish between the different types of achondrogenesis? What is the chance of having another child with this condition?

Our Answer

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

How can I find a genetics professional in my area?

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. 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: 10/18/2013

What is achondrogenesis?

Achondrogenesis is a group of severe disorders that are present from birth and affect the development of cartilage and bone. Infants with achondrogenesis usually have a small body, short arms and legs, and other skeletal abnormalities that cause life-threatening complications.[1]  There are at least three forms of achondrogenesis, type 1A, type 1B and type 2, which are distinguished by signs and symptoms, pattern of inheritance, and the results of imaging studies such as x-rays (radiology), tissue analysis (histology), and genetic testing. [2] Type 1A and 1B achondrogenesis are both inherited in an autosomal recessive pattern.  Type 1B may be caused by mutations in the SLC26A2 gene.  Type 2 achondrogenesis is inherited in an autosomal dominant pattern and is caused by new (de novo) mutations in the COL2A1 gene.[1]
Last updated: 10/18/2013

What causes achondrogenesis?

Research has shown that changes (mutations) in the SLC26A2 and COL2A1 genes cause achondrogenesis types 1B and 2, respectively. The genetic cause of achondrogenesis type 1A remains unknown. 

The SLC26A2 gene provides instructions for making a protein that is important for the normal development of cartilage and for the conversion of cartilage to bone. The COL2A1 gene provides instructions for making a protein that forms a type of collagen found mostly in cartilage and in the clear gel that fills the eyeball (vitreous).  Mutations in these genes result in the production of proteins that are unable to properly perform their jobs within the body.[1]
Last updated: 10/29/2010

How is achondrogenesis inherited?

Achondrogenesis type 1A and type 1B are believed to be inherited in an autosomal recessive pattern.  Autosomal recessive inheritance means both copies of the gene in each cell have mutations.  Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.

Achondrogenesis type 2 is considered an autosomal dominant disorder because one copy of the altered gene in each cell is sufficient to cause the condition. It is almost always caused by new (de novo) mutations and typically occurs in people with no history of the disorder in their family.[1]
Last updated: 10/29/2010

Is genetic testing is available for achondrogenesis?

Genetic testing can help distinguish between the different types of achondrogenesis. GeneTests lists the names of laboratories that are performing genetic testing for achondrogenesis type 1B and type 2.

Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional. In the Services tab, we provide a list of online resources that can assist you in locating a genetics professional near you.
Last updated: 10/29/2010

What is the chance of having another child with achondrogenesis?    

The chance of having another child with achondrogenesis depends on the specific type the condition. 

Achondrogenesis type 1A and 1B are both believed to be inherited in an autosomal recessive pattern.  When both parents are carriers for an autosomal recessive condition, there is a 25% (1 in 4) chance in each pregnancy of having a child with the condition.

Achondrogenesis type 2 is almost always caused by new (de novo) mutations so the chance that a couple will to have another child with achondrogenesis type 2 is very low. [1]

To find out your specific risk of having a child with achondrogenesis, we recommend that you consult with a genetics professional.
Last updated: 10/29/2010