Achondrogenesis
Updates to Article Attributes
Achondrogenesis refers to a group of rare and extreme skeletal dysplasias.
Epidemiology
The estimated incidence is 1:40,000 with no recognised gender predilection.
Pathology
It is classified as an osteochondrodysplasias, meaning deficiency of both bone and cartilage development.
Sub typesSubtypes
There are several recognised sub types:
-
type I
- type Ia: Houston-Harris sub type
- type Ib: Parenti-Fraccaro sub type
- type II: Langer-Saldino achondrogenesis
Genetics
There are various patterns of inheritance ranging from autosomal dominant to autosomal recessive forms. Type II achondrogenesis is thought to be sporadic.
Radiographic features
Antenatal ultrasound
Sonographic diagnosis may be possible after 13 weeks where nuchal oedema may be evident as an early (although non specific) sign.
The fetal bony structures are often unable to be identified. There may also be extreme micromelia 5. Calvarial ossification can be preserved with the type II sub type which can in turn give a floating head appearence.
Additional sonographic findings include:
- micrognathia
- narrow fetal thorax
- rib fractures can be present in type Ia
- disproportionately small body compared with head
Other ancilliary sonographic features that may be present include
- polyhydramnios
- development of hydrops fetalis
Prognosis
The prognosis is generally poor with most infants being stillborn or dying soon after birth.
Differential diagnosis
General considerations for mild cases include:
For an absent calvarial bone(s) (type Ia / Ib/Ib) on antenatal ultrasound consider:
See also
-<p><strong>Achondrogenesis</strong> refers to a <strong>group</strong> of rare and extreme <a href="/articles/skeletal-dysplasia">skeletal dysplasias</a>.</p><h4>Epidemiology</h4><p>The estimated incidence is 1:40,000 with no recognised gender predilection.</p><h4>Pathology</h4><p>It is classified as an <a href="/articles/osteochondrodysplasias">osteochondrodysplasias</a>, meaning deficiency of <strong>both</strong> bone and cartilage development.</p><h5>Sub types</h5><p>There are several recognised sub types:</p><ul>- +<p><strong>Achondrogenesis</strong> refers to a <strong>group</strong> of rare and extreme <a href="/articles/skeletal-dysplasia">skeletal dysplasias</a>.</p><h4>Epidemiology</h4><p>The estimated incidence is 1:40,000 with no recognised gender predilection.</p><h4>Pathology</h4><p>It is classified as an <a href="/articles/osteochondrodysplasias">osteochondrodysplasias</a>, meaning deficiency of <strong>both</strong> bone and cartilage development.</p><h5>Subtypes</h5><p>There are several recognised sub types:</p><ul>
-</ul><h4>Prognosis</h4><p>The prognosis is generally poor with most infants being stillborn or dying soon after birth. </p><h4>Differential diagnosis</h4><p>General considerations for mild cases include</p><ul><li><a href="/articles/hypochondrogenesis">hypochondrogenesis</a></li></ul><p>For an absent calvarial bone(s) (type Ia / Ib) on antenatal ultrasound consider</p><ul><li><a href="/articles/acrania">acrania</a></li></ul><h4>See also</h4><ul><li><a href="/articles/achondroplasia">achondroplasia</a></li></ul>- +</ul><h4>Prognosis</h4><p>The prognosis is generally poor with most infants being stillborn or dying soon after birth. </p><h4>Differential diagnosis</h4><p>General considerations for mild cases include:</p><ul><li><a href="/articles/hypochondrogenesis">hypochondrogenesis</a></li></ul><p>For an absent calvarial bone(s) (type Ia/Ib) on antenatal ultrasound consider:</p><ul><li><a href="/articles/acrania">acrania</a></li></ul><h4>See also</h4><ul><li><a href="/articles/achondroplasia">achondroplasia</a></li></ul>
References changed:
- 9. Reinhard Schumacher, Laurie H. Seaver, Jürgen Spranger. Fetal Radiology. (2010) ISBN: 9783642035593 - <a href="http://books.google.com/books?vid=ISBN9783642035593">Google Books</a>
- 12. Schumacher R, Seaver LH, Spranger J. Fetal Radiology, A Diagnostic Atlas. Springer Verlag. (2011) ISBN:3642035590. <a href="http://books.google.com/books?vid=ISBN3642035590">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/3642035590?ie=UTF8&tag=radiopaediaor-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=3642035590">Find it at Amazon</a><div class="ref_v2"></div>
- 9. <a href= "http://roentgenrayreader.blogspot.com/2009/05/achondrogenesis.html"> http://roentgenrayreader.blogspot.com/2009/05/achondrogenesis.html