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
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Scientists at Hacettepe University, Department of Pediatrics detail research in skeletal dysplasia genetics
2007 JUL 10 -- Current study results from the report, "Angulated femurs and the skeletal dysplasias: experience of the International Skeletal Dysplasia Registry (1988-2006)," have been published. According to recent research from Ankara, Turkey, "Angulated or bent femur (isolated or associated with other long bone bowing) in the fetus or newborn is relatively common when evaluating patients with skeletal dysplasias. To determine the extent and heterogeneity of disorders associated with angulated or bent femurs, we analyzed cases in the radiographic database (1998-2006) of the International Skeletal Dysplasia Registry (ISDR) and determined which established skeletal dysplasias and genetic syndromes are associated with this finding." "The results show that more than 40 distinct disorders with varying frequency (very rare to more commonly occurring disorders) can be associated with bowed/bent/angulated femurs. Sixty-six percent of the cases with angulated femurs belonged to three well described groups of disorders; campomelic disorders (24.4%), thanatophoric dysplasia (23.9%) and osteogenesis imperfecta (OI) (18.1%). With specific emphasis on these, this cross-sectional cohort provides discussion of data on other rare disorders associated with angulated femurs and the importance of the finding relative to its occurrence within a diagnostic group," wrote Y. Alanay and colleagues, Hacettepe University, Department of Pediatrics. The researchers concluded: "This study aims to provide differential diagnosis of entities to be considered when a fetus or newborn is found to have congenital bowing/angulation of the femur." Alanay and colleagues published their study in American Journal of Medical Genetics Part A (Angulated femurs and the skeletal dysplasias: experience of the International Skeletal Dysplasia Registry (1988-2006). American Journal of Medical Genetics Part A, 2007;143(11):1159-68). For additional information, contact Y. Alanay, Clinical Genetics Unit, Dept. of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey. Publisher contact information for the American Journal of Medical Genetics Part A is: Wiley-Liss, Division John Wiley & Sons Inc., 111 River St., Hoboken, NJ 07030, USA. Keywords: Turkey, Ankara, Skeletal Dysplasia Genetics, Dermatology, Genetics, Skeletal Dysplasia. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2007, Life Science Weekly via NewsRx.com.
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