Thanatophoric Dysplasia
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What is thanatophoric dysplasia?
Thanatophoric dysplasia is a severe skeletal disorder characterized by extremely short limbs and folds of extra (redundant) skin on the arms and legs. Other features of this condition include a narrow chest, short ribs, underdeveloped lungs, and an enlarged head with a large forehead and prominent, wide-spaced eyes.
Researchers have described two major forms of thanatophoric dysplasia, type I and type II. Type I thanatophoric dysplasia is distinguished by the presence of curved thigh bones and flattened bones of the spine (platyspondyly). Type II thanatophoric dysplasia is characterized by straight thigh bones and a moderate to severe skull abnormality called a cloverleaf skull.
The term thanatophoric is Greek for death bearing. Infants with thanatophoric dysplasia are usually stillborn or die shortly after birth from respiratory failure; however, a few affected individuals have survived into childhood with extensive medical help.
How common is thanatophoric dysplasia?
This condition occurs in 1 in 20,000 to 50,000 newborns. Type I thanatophoric dysplasia is more common than type II.
What genes are related to thanatophoric dysplasia?
Mutations in the FGFR3 gene cause thanatophoric dysplasia.
Both types of thanatophoric dysplasia result from mutations in the FGFR3 gene. This gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. Mutations in this gene cause the FGFR3 protein to be overly active, which leads to the severe disturbances in bone growth that are characteristic of thanatophoric dysplasia. It is not known how FGFR3 mutations cause the brain and skin abnormalities associated with this disorder.
How do people inherit thanatophoric dysplasia?
Thanatophoric dysplasia is considered an autosomal dominant disorder because one mutated copy of the FGFR3 gene in each cell is sufficient to cause the condition. Virtually all cases of thanatophoric dysplasia are caused by new mutations in the FGFR3 gene and occur in people with no history of the disorder in their family. No affected individuals are known to have had children; therefore, the disorder has not been passed to the next generation.
Source: National Institutes of Health
Research on life sciences published by scientists at Dalhousie University, Medical Department
2009 MAY 12 - (NewsRx.com) -- "Cloverleaf skulls (Kleeblattschadel-Syndromen, trilobular skulls) have different modes of development (pathogenetic variability). Synostosis may involve various sutures in different types of cloverleaf skulls," investigators in Halifax, Canada report. "Their facial features, radiographic findings, and CNS anomalies are also reviewed. Different causes of cloverleaf skulls have been identified (etiologic heterogeneity). One table lists 26 different conditions with trilobular skulls identified under various etiologic headings: monogenic, chromosomal, disruptive, iatrogenic, and distinctive conditions of unknown cause. Discussed in detail are type 2 thanatophoric dysplasia, type 2 Pfeiffer syndrome, Apert syndrome, amniotic bands, Say-Poznanski syndrome, and COH syndrome," wrote M.M. Cohen and colleagues, Dalhousie University, Medical Department. The researchers concluded: "Another table summarizes the relative frequencies of the cloverleaf skull syndromes." Cohen and colleagues published their study in the Journal of Craniofacial Surgery (Cloverleaf Skulls: Etiologic Heterogeneity and Pathogenetic Variability. Journal of Craniofacial Surgery, 2009;20(Suppl. 1):652-656). For additional information, contact M.M. Cohen, Dalhousie University, Faculty Medical, Dept. of Pediatrics, 5981 University Avenue, Halifax, NS B3H 1W2, Canada. The publisher of the Journal of Craniofacial Surgery can be contacted at: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA. Keywords: Canada, Halifax, Life Sciences, Amniotic Band Syndrome, Acrocephalosyndactylia, Apert Syndrome, Synostosis, Dermatology, Dysplasia, Surgery, Dalhousie University, Medical Department. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2009, Life Science Weekly via NewsRx.com.
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