Postaxial polydactyly
Updates to Article Attributes
Postaxial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5th (little) toe.
Epidemiology
Postaxial polydactyly is more common than preaxial polydactyly, with an estimated incidence of 1 in 3000 5.
Associations
Postaxial polydactyly can be associated with:
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following oral-facial-digital syndromes (OFDS)
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certain skeletal dysplasias
certain short rib polydactyly syndromes: e.g. types I and III
Pathology
The majority of cases are idiopathic. Associations with mutations to the GLI3 gene on chromosome 7 as well as a second locus mapped to chromosome 13 have been implicated in postaxial polydactyly 5.
Classification
Several different classification systems exist for post-axialpostaxial polydactyly of the hands, including the (a) Pritsch, (b) Rayan and Al-Qattan, and (c) Duran classification systems.
Duran et al. introduced their new classification system for post-axial polydactyly in 2015 6. This new classification was created as it was felt that the current systems in use were not comprehensive for coverage of the different post-axial forms.
type I: skin nub without nail or bone elements
type II: hypoplastic proximal phalanx
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type III: proximal phalangeal malformations
IIIA: bifid proximal phalanx
IIIB: duplicated proximal phalanx
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type IV: metacarpal malformations
:IV-AIVA: fusion of the metacarpalIV-BIVB: bifid metacarpalIV-CIVC: duplication of the metacarpal
type V: (complicated type) with triplication of the small finger, polysyndactyly, or both
-<li><p><a href="/articles/oral-facial-digital-syndrome-ofds-type-ii">oral-facial-digital syndrome (OFDS) type II </a>- <a href="/articles/mohr-syndrome">Mohr syndrome</a></p></li>- +<li><p><a href="/articles/oral-facial-digital-syndrome-ofds-type-ii">oral-facial-digital syndrome (OFDS) type II (Mohr syndrome)</a></p></li>
-<li><p><a href="/articles/chondroectodermal-dysplasia">chondroectodermal dysplasia </a>- <a href="/articles/chondroectodermal-dysplasia">Ellis-van Creveld syndrome</a></p></li>-<li><p><a href="/articles/asphyxiating-thoracic-dysplasia">asphyxiating thoracic dysplasia </a>- <a href="/articles/asphyxiating-thoracic-dysplasia">Jeune syndrome</a></p></li>- +<li><p><a href="/articles/chondroectodermal-dysplasia" title="Chondroectodermal dysplasia">chondroectodermal dysplasia (Ellis-van Creveld syndrome)</a></p></li>
- +<li><p><a href="/articles/asphyxiating-thoracic-dysplasia">asphyxiating thoracic dysplasia (Jeune syndrome)</a></p></li>
-<li><p>certain <a href="/articles/short-rib-polydactyly-syndrome">short rib polydactyly syndromes</a>: e.g types I and III</p></li>-</ul><h4>Pathology</h4><p>The majority of cases are idiopathic. Associations with mutations to the <em>GLI3 </em>gene on chromosome 7 as well as a second locus mapped to chromosome 13 have been implicated in postaxial polydactyly <sup>5</sup>.</p><h5>Classification</h5><p>Several different classification systems exist for post-axial polydactyly of the hands, including the (a) Pritsch, (b) Rayan and Al-Qattan, and (c) Duran classification systems.</p><p>Duran et al introduced their new classification system for post-axial polydactyly in 2015 <sup>6</sup>. This new classification was created as it was felt that the current systems in use were not comprehensive for coverage of the different post-axial forms.</p><ul>-<li><p>type I: skin nub without nail or bone elements</p></li>-<li><p>type II: hypoplastic proximal phalanx</p></li>- +<li><p>certain <a href="/articles/short-rib-polydactyly-syndrome">short rib polydactyly syndromes</a>: e.g. types I and III</p></li>
- +</ul><h4>Pathology</h4><p>The majority of cases are idiopathic. Associations with mutations to the <em>GLI3 </em>gene on chromosome 7 as well as a second locus mapped to chromosome 13 have been implicated in postaxial polydactyly <sup>5</sup>.</p><h5>Classification</h5><p>Several different classification systems exist for postaxial polydactyly of the hands, including the (a) Pritsch, (b) Rayan and Al-Qattan, and (c) Duran classification systems.</p><p>Duran et al. introduced their new classification system for post-axial polydactyly in 2015 <sup>6</sup>. This new classification was created as it was felt that the current systems in use were not comprehensive for coverage of the different post-axial forms.</p><ul>
- +<li><p><strong>type I:</strong> skin nub without nail or bone elements</p></li>
- +<li><p><strong>type II:</strong> hypoplastic proximal phalanx</p></li>
-<p>type III: proximal phalangeal malformations</p>- +<p><strong>type III:</strong> proximal phalangeal malformations</p>
-<li><p>IIIA: bifid proximal phalanx</p></li>-<li><p>IIIB: duplicated proximal phalanx</p></li>- +<li><p><strong>IIIA: </strong>bifid proximal phalanx</p></li>
- +<li><p><strong>IIIB: </strong>duplicated proximal phalanx</p></li>
-<p>type IV: metacarpal malformations:</p>- +<p><strong>type IV:</strong> metacarpal malformations</p>
-<li><p>IV-A: fusion of the metacarpal</p></li>-<li><p>IV-B: bifid metacarpal</p></li>-<li><p>IV-C: duplication of the metacarpal</p></li>- +<li><p><strong>IVA:</strong> fusion of the metacarpal</p></li>
- +<li><p><strong>IVB:</strong> bifid metacarpal</p></li>
- +<li><p><strong>IVC:</strong> duplication of the metacarpal</p></li>
-<li><p>type V (complicated type) with triplication of the small finger, polysyndactyly, or both</p></li>- +<li><p><strong>type V:</strong> (complicated type) with triplication of the small finger, polysyndactyly, or both</p></li>
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