Thanatophoric dysplasia
Updates to Article Attributes
Thanatophoric dysplasia (TD) is a lethal skeletal dysplasia. It is the 2ndafterfollowed by osteogenesis imperfecta type II.
Epidemiology
The estimated incidence is around 1:25,000-50,000 3.
Pathology
Genetics
It results from a mutation coding for the fibroblast growth receptor 3 (FGFR3) located inon chromosome 4p16.3. The type of receptor mutation is different from the FGFR mutation in achondroplasia. Inheritance is thought to be sporadic.
Subtypes
There are two recognised subtypes.:
-
type I: marked underdevelopment of skeleton, telephone handle femurs more pronounced
. -
type II
- the presence of a cloverleaf skull may be a distinctive feature
- limb shortening milder and bowing is not a feature 3
Associations
Radiographic features
Antenatal ultrasound
It may be difficult to accurately diagnose before the 3rd trimester (≈22 weeks) 4. Prior toBefore that time it can be in included in the differential if there is a short femur length measurement.
Sonographically detectable features may include:
- relatively narrow thoracic cavity 4
- short, thick, bowed tubular bones, especially lower extremity 4
- thickened soft tissues of extremities 4
- comparatively large head with frontal bossing
- a cloverleaf skull appearance may also be seen: type II (see case 3)
Plain filmradiograph
Plain films are usually done post-mortem, if done at all. Features include:
Limbs
- proximal portions of the long limbs are small, giving a rhizomelic appearance
- long bones (typically humeri and femora) have a typical "telephone handle" bowing with metaphyseal flaring
Iliac bones
- usually hypoplastic
- small squared iliac wings
- may show a "trident" acetabular roof
Chest
- narrow chest
- short horizontal ribs
- small scapulae
Skull and face
- relative macrocephaly
- frontal bossing
- proptosis
- nasal bridge flattening
- Kleeblattschaedel, or cloverleafskull (with type II) 2-4
Spine
- platyspondyly: flattening of vertebral bodies
- normal trunk length
Treatment and prognosis
The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.
History and etymology
The term thanatophoric derives from the Greek words "thanatos" (θάνατος) meaning "death" 2 and "foros" meaning "bearing/carrying/bringing".
Prognosis
The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.
See also
-<p><strong>Thanatophoric dysplasia (TD)</strong> is a <a href="/articles/lethal-skeletal-dysplasias">lethal skeletal dysplasia</a>. It is the 2<sup>nd</sup> most common lethal skeletal dysplasia after <a href="/articles/osteogenesis-imperfecta-1">osteogenesis imperfecta</a> type II. </p><h4>Epidemiology</h4><p>The estimated incidence is around 1:25,000-50,000 <sup>3</sup>.</p><h4>Pathology</h4><h5>Genetics</h5><p>It results from a mutation coding for the fibroblast growth receptor 3 (FGFR3) located in chromosome 4p16.3. The type of receptor mutation is different from the FGFR mutation in <a href="/articles/achondroplasia">achondroplasia</a>. Inheritance is thought to be sporadic.</p><h5>Subtypes</h5><p>There are two recognised subtypes.</p><ul>- +<p><strong>Thanatophoric dysplasia (TD)</strong> is a <a href="/articles/lethal-skeletal-dysplasias">lethal skeletal dysplasia</a>. It is the most common lethal skeletal dysplasia followed by <a href="/articles/osteogenesis-imperfecta-1">osteogenesis imperfecta</a> type II. </p><h4>Epidemiology</h4><p>The estimated incidence is around 1:25,000-50,000 <sup>3</sup>.</p><h4>Pathology</h4><h5>Genetics</h5><p>It results from a mutation coding for the fibroblast growth receptor 3 (FGFR3) located on chromosome 4p16.3. The type of receptor mutation is different from the FGFR mutation in <a href="/articles/achondroplasia">achondroplasia</a>. Inheritance is thought to be sporadic.</p><h5>Subtypes</h5><p>There are two recognised subtypes:</p><ul>
-<strong>type I:</strong> marked underdevelopment of skeleton, telephone handle femurs more pronounced.</li>- +<strong>type I:</strong> marked underdevelopment of skeleton, telephone handle femurs more pronounced</li>
-</li></ul><h4>Radiographic features</h4><h5>Antenatal ultrasound</h5><p>It may be difficult to accurately diagnose before the 3<sup>rd</sup> trimester (≈22 weeks) <sup>4</sup>. Prior to that time it can be in included in the differential if there is a short femur length measurement. </p><p>Sonographically detectable features may include:</p><ul>- +</li></ul><h4>Radiographic features</h4><h5>Antenatal ultrasound</h5><p>It may be difficult to accurately diagnose before the 3<sup>rd</sup> trimester (≈22 weeks) <sup>4</sup>. Before that time it can be in included in the differential if there is a short femur length measurement. </p><p>Sonographically detectable features may include:</p><ul>
-</ul><h5>Plain film </h5><p>Plain films are usually done post-mortem, if done at all. Features include:</p><h6>Limbs</h6><ul>- +</ul><h5>Plain radiograph </h5><p>Plain films are usually done post-mortem if done at all. Features include:</p><h6>Limbs</h6><ul>
-</ul><h4>History and etymology</h4><p>The term thanatophoric derives from the Greek words "thanatos" (θάνατος) meaning "death" <sup>2</sup> and "foros" meaning "bearing/carrying/bringing". </p><h4>Prognosis</h4><p>The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.</p><h4>See also</h4><ul><li><a href="/articles/skeletal-dysplasia">skeletal dysplasias</a></li></ul>- +</ul><h4>Treatment and prognosis</h4><p>The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.</p><p><strong style="font-size:1.5em; font-weight:bold">History and etymology</strong></p><p>The term thanatophoric derives from the Greek words "thanatos" (θάνατος) meaning "death" <sup>2</sup> and "foros" meaning "bearing/carrying/bringing". </p><p><strong style="font-size:1.5em; font-weight:bold">See also</strong></p><ul><li><a href="/articles/skeletal-dysplasia">skeletal dysplasias</a></li></ul>
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