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Achondrogenesis Type 1B

What is Achondrogenesis Type 1B?

Achondrogenesis type 1B (ACG1B) is a severe skeletal disease that is fatal either before or shortly after birth.

Infants born with the disease have extremely short arms, legs, fingers, and toes. The fingers and toes may be rotated inward. Infants with the disease also tend to have flat faces, protruding abdomens, narrow chests, and short necks that show thickening of the soft tissue. Many are born with hernias.

Fetuses with ACG1B are often in the breech position, “upside-down” with their feet toward the birth canal. Mothers of fetuses with ACG1B are prone to certain other pregnancy complications.

The disease is caused by a mutation in a gene that plays a role in making cartilage and bone. The cause of death in these infants is not well understood.

How common is Achondrogenesis Type 1B?

ACG1B is rare, but its frequency is unknown. One particular mutation that causes the disease is most common in Finland, but other mutations are found globally.

How is Achondrogenesis Type 1B treated?

There is no treatment for ACG1B. Infants with the disease can only be made as comfortable as possible.

What is the prognosis for a person with Achondrogenesis Type 1B?

The prognosis for an infant with ACG1B is poor. They will die before or shortly after birth.



A medical database of genetic disorders funded by the National Institutes of Health and developed at the University of Washington, Seattle. Much of the language in GeneReviews is meant for physicians and other scientists.

Genetics Home Reference

Explanations of an extensive number of genetic diseases written for everyday people by the U.S. government's National Institutes of Health. Note that the article refers to several forms of achondrogenesis, type 1B among them.

International Skeletal Dysplasia Registry

A group within Cedars Sinai Medical Center, it collects research into the diagnosis and management of skeletal dysplasias including achondrogenesis.

Medical Genetics Institute
8700 Beverly Boulevard, Suite 665W
Los Angeles, CA 90048
Phone: (800) 233-2771

Other names for Achondrogenesis Type 1B

  • Achondrogenesis, Fraccaro Type
  • Sulfate Transporter-Related Osteochondrodysplasia
  • ACG1B
  • Achondrogenesis Type IB
  • Achondrogenesis Type 1B

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