Thanatophoric dysplasia
(Redirected from Dwarfism thanatophoric)
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.
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]
- 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
- [[Brachydactyly](Short fingers or toes)
- Frontal bossing
- Gray matter heterotopia
- Hearing impairment(Deafness)
- Intrauterine growth retardation(Prenatal growth deficiency)
- Midface retrusion(Decreased size of midface)
- Proptosis(Bulging eye)
- Ventriculomegaly
5%-29% of people have these symptoms
- Abnormality of the kidney(Abnormal kidney)
- Abnormality of the sacroiliac joint
- Acanthosis nigricans(Darkened and thickened skin)
- Atrial septal defect(An opening in the wall separating the top two chambers of the heart)
- Cloverleaf skull
- Downslanted palpebral fissures(Downward slanting of the opening between the eyelids)
- Hip dysplasia
- Hydrocephalus(Too much cerebrospinal fluid in the brain)
- Joint hyperflexibility(Joints move beyond expected range of motion)
- Joint stiffness(Stiff joint)
- Kyphosis(Hunched back)
- Low-set ears(Low set ears)
- Patent ductus arteriosus
- Polyhydramnios(High levels of amniotic fluid)
- Respiratory insufficiency(Respiratory impairment)
- Seizure
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]
- Most infants with thanatophoric dysplasia are stillborn or die shortly after birth from respiratory failure. [2][2].
- A few affected individuals have survived into childhood with extensive medical help.
- Newborns require long-term respiratory support (typically with tracheostomy and ventilation) to survive.
- Anesthetic management is done for skeletal dysplasias to individuals with TD.
- Shunt placement for hydrocephalus
- suboccipital decompression for relief of craniocervical junction constriction
- Antiepileptic drugs to control seizures and hearing aids.
References[edit | edit source]
- ↑ 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/
- ↑ 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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