Type 1B, Lethal Achondrogenesis, Parenti-Fraccaro Type
Monday, 26 January 2004
Last Updated Thursday, 18 November 2004
What
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.
Who
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.
Diagnosis
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.
Treatment
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.
Prognosis
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.
Weblinks
http://www.nlm.nih.gov/medlineplus/ency/article/001247.htm
Very nice, informative site from the National Institutes of Health.
http://www.lpaonline.org/
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. http://cancerweb.ncl.ac.uk/cqi-bin/omd?achondrogenesis.
Online Mendelian Inheritance of Man.
www.ncbi.nlm.nih.gov/omim/
“Achondrogenesis” MedLine Plus. www.nlm.nih.gov/medlineplus
Chen, Harold. “Achondrogenesis” www.emedicine.com/ped/topic11.htm.