Achondrogenesis

What causes achondrogenesis?

Changes (mutations) in the TRIP11 , SLC26A2 and COL2A1 genes cause achondrogenesis types 1A, 1B and 2, respectively. The TRIP11 gene provides instructions for making a protein that is involved in forming the Golgi body, an important structure found in most cells of the body. 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.

Last updated on 05-01-20

How is achondrogenesis diagnosed?

Achondrogenesis can be diagnosed during pregnancy by ultrasound as early as 12-14 weeks. At birth, this condition is suspected when the infant has extremely short underdeveloped arms and legs, short ribs and small chest, and short trunk. X-ray findings include underdeveloped skull, vertebrate and rib cage. Genetic testing of the TRIP11 , SLC26A2 and COL2A1 genes can be performed to confirm the diagnosis and determine the type of achondrogenesis.

Last updated on 05-01-20

How is achondrogenesis inherited?

Achondrogenesis type 1A and type 1B are believed to be inherited in an autosomal recessive pattern. This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. There is nothing either parent can do, before or during a pregnancy, to cause a child to have this condition.

Infants with achondrogenesis inherit one mutation from each of their parents. The parents, who each have one mutation, are known as carriers. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:

  • 25% chance to be affected
  • 50% chance to be an unaffected carrier like each parent
  • 25% chance to be unaffected and not a carrier

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 caused by a new (de novo) mutation and usually occurs in people with no history of the disorder in their family. There are rare cases of families who have had more than one pregnancy with achondrogenesis type 2. These cases are thought to occur because of mosaicism, which means that a portion of the DNA in a person's cells is different than the DNA in the rest of his/her body. Germline mosaicism occurs then a person's reproductive cells (sperm or egg) carry a mutation not found in the rest of the cells in the body. Somatic mosaicism occurs when a person has a some body cells that carry a mutation and some body cells that do not carry the mutation. Individuals with germline or somatic mosaicism are generally healthy and do not show signs of the disorder.

Last updated on 05-01-20

What is the long-term outlook for infants with achondrogenesis?

Most infants with achondrogenesis have severely underdeveloped lungs which leads to serious breathing problems and lung failure. Most die before or shortly after birth because of the severity of this disorder.

Last updated on 05-01-20

How many people have achondrogenesis?

Achondrogenesis affects males and females in equal numbers. Achondrogenesis type 1A and type 1B are very rare disorders and the prevalence for them is unknown. Achondrogenesis type 2 occurs in approximately 1/40,000-1/60,000 newborns.

Last updated on 05-01-20

How might achondrogenesis be treated?

Medical care for achondrogenesis is focused on addressing any symptoms and relieving pain. Genetic counseling is recommended for families with a diagnosis of achondrogenesis.

Last updated on 05-01-20

Name: European Skeletal Dysplasia Network Institute of Genetic Medicine Newcastle University
International Centre for Life Central Parkway New Castle upon Tyne
NE1 3BZ, United Kingdom
Email: info@esdn.org Url: http://www.esdn.org/eug/Home
Name: Compassionate Friends P.O. Box 3696
Oak Brook, IL, 60522-3696 , United States
Phone: 630-990-0010 Toll Free: 877-969-0010 Fax : 630-990-0246 Email: nationaloffice@compassionatefriends.org Url: http://www.compassionatefriends.org
Name: SHARE - Pregnancy and Infant Loss Support, Inc. 402 Jackson Street
Saint Charles, MO, 63301-3468,
Phone: 800-821-6819 Email: info@nationalshare.org Url: http://www.nationalshare.org/
Name: European Skeletal Dysplasia Network Institute of Genetic Medicine Newcastle University
International Centre for Life Central Parkway New Castle upon Tyne
NE1 3BZ, United Kingdom
Email: info@esdn.org Url: http://www.esdn.org/eug/Home

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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