Thanatophoric dysplasia

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Alternate names[edit | edit source]

Dwarfism thanatophoric; Thanatophoric Dwarfism; TD

Definition[edit | edit source]

Thanatophoric dysplasia is a severe skeletal disorder characterized by extremely short limbs and folds of extra (redundant) skin on the arms and legs.

Summary[edit | edit source]

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.

Thanatophoric dysplasia

Types[edit | edit source]

  • 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

Epidemiology[edit | edit source]

This condition occurs in 1 in 20,000 to 50,000 newborns. Type I thanatophoric dysplasia is more common than type II.

Cause[edit | edit source]

  • Mutations in the FGFR3 gene cause thanatophoric dysplasia.
  • Both types of this condition 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.

Gene mutations[edit | edit source]

  • 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.

Inheritance[edit | edit source]

Autosomal dominant pattern, a 50/50 chance.
  • 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.

Signs and symptoms[edit | edit source]

  • This condition is characterized by extremely short limbs and folds of extra 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.
  • Most infants with thanatophoric dysplasia are stillborn or die shortly after birth from respiratory failure.
  • A few affected individuals have survived into childhood with extensive medical help.

Clinical presentation[edit | edit source]

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

  • Abnormality of the metaphysis(Abnormality of the wide portion of a long bone)
  • Depressed nasal bridge(Depressed bridge of nose)
  • Disproportionate short-limb short stature(Short limb dwarfism, disproportionate)
  • Flat face(Flat facial shape)
  • Increased nuchal translucency
  • Intellectual disability, profound(IQ less than 20)
  • Macrocephaly(Increased size of skull)
  • Micromelia(Smaller or shorter than typical limbs)
  • Muscular hypotonia(Low or weak muscle tone)
  • Narrow chest(Low chest circumference)
  • Platyspondyly(Flattened vertebrae)
  • Pulmonary hypoplasia(Small lung)
  • Redundant skin(Loose redundant skin)
  • Short thorax(Shorter than typical length between neck and abdomen)
  • Skeletal dysplasia

30%-79% of people have these symptoms

5%-29% of people have these symptoms

Diagnosis[edit | edit source]

The diagnosis of this condition with characteristic clinical ,radiologic features ,a heterozygous pathogenic variant in FGFR3 identified on molecular genetic testing.[1][1].


Treatment[edit | edit source]


References[edit | edit source]

  1. French T, Savarirayan R. Thanatophoric Dysplasia. 2004 May 21 [Updated 2020 Jun 18]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1366/
  2. French T, Savarirayan R. Thanatophoric Dysplasia. 2004 May 21 [Updated 2020 Jun 18]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1366/


NIH genetic and rare disease info[edit source]

Thanatophoric dysplasia is a rare disease.


Thanatophoric dysplasia Resources

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