Classification
There are several ways to classify craniosynostosis.
- For example, one can consider the number of closed sutures. If only one of the four sutures is prematurely closed (single suture craniosynostosis), the craniosynostosis is referred to as ‘simple’ (or ‘isolated’). Whereas when two or more sutures are no longer open, the craniosynostosis is ‘complex’.
- A second classification scheme gives a clinical description of the resulting shape of the skull. This will be further discussed under phenotype.
- A third classification involves the presence or absence of an identified craniofacial syndrome. Craniosynostosis where no extracranial deformations are present, is called non-syndromic or ‘isolated’ craniosynostosis. When there are extracranial deformations present, for instance involving the limbs, heart, central nervous system or the respiratory tract, you may speak of a syndromic form of craniosynostosis. More than 180 identified syndromes show deformations due to craniosynostosis. The following syndromes are associated with fibroblast growth factor receptors:
| Name of syndrome | Other signs and symptoms (along with craniosynostosis; may not all be present) | OMIM reference | Gene |
|---|---|---|---|
| Crouzon syndrome | wide-set, bulging eyes • beaked nose • flat face | 123500 | FGFR2, FGFR3 |
| Apert syndrome | fused fingers or toes • flat midface | 101200 | FGFR2 |
| Crouzonodermoskeletal syndrome | wide-set, bulging eyes • beaked nose • flat face • dark, velvety skin folds • spine abnormalities • benign growths in the jaw | 134934 | FGFR3 |
| Jackson-Weiss syndrome | enlarged, bent big toes • flat midface | 123150 | FGFR1, FGFR2 |
| Muenke syndrome | coronal synostosis • skeletal abnormalities of the hands or feet • hearing loss | 602849 | FGFR3 |
| Pfeiffer syndrome | broad, short thumbs or big toes • webbed or fused fingers or toes | 101600 | FGFR1, FGFR2 |
In addition, the following syndromes have been identified:
| Name of syndrome | Other signs and symptoms (along with craniosynostosis; may not all be present) | OMIM reference | Gene |
|---|---|---|---|
| Loeys-Dietz syndrome | wide-set eyes • split uvula or cleft palate • arterial tortuosity • aortic root dilatation • aneurysms | 609192 610168 613795 608967 610380 | TGFBR1, TGFBR2, SMAD3 |
| Saethre-Chotzen syndrome | facial asymmetry • low frontal hairline • drooping eyelids • webbed fingers or toes • broad big toes | 101400 | TWIST1 |
| Shprintzen-Goldberg syndrome | bulging eyes • flat face • hernias • long, thin fingers • developmental delay • mental retardation | 182212 | FBN1 |
Read more about this topic: Craniosynostosis