Grant Sponsor: Public Health Service; Grant numbers: R01 DE018500; 3R01 DE18500-02S1; R01 DE016886; CDC 5R01 DD000350.
Unilateral and bilateral expression of a quantitative trait: asymmetry and symmetry in coronal craniosynostosis
Article first published online: 24 APR 2012
© 2011 WILEY PERIODICALS, INC.
Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
Volume 318, Issue 2, pages 109–122, March 2012
How to Cite
How to cite this article: 2011. Unilateral and bilateral expression of a quantitative trait: asymmetry and symmetry in coronal craniosynostosis. J. Exp. Zool. (Mol. Dev. Evol.) 31: 109–122., , , , , , .
- Issue published online: 24 APR 2012
- Article first published online: 24 APR 2012
- Manuscript Accepted: 13 SEP 2011
- Manuscript Revised: 1 SEP 2011
- Manuscript Received: 28 APR 2011
- Public Health Service. Grant Numbers: R01 DE018500, 3R01 DE18500-02S1, R01 DE016886, CDC 5R01 DD000350
Bilateral symmetry in vertebrates is imperfect and mild asymmetries are found in normal growth and development. However, abnormal development is often characterized by strong asymmetries. Coronal craniosynostosis, defined here as consisting of premature suture closure and a characteristic skull shape, is a complex trait. The premature fusion of the coronal suture can occur unilaterally associated with skull asymmetry (anterior plagiocephaly) or bilaterally associated with a symmetric but brachycephalic skull. We investigated the relationship between coronal craniosynostosis and skull bilateral symmetry. Three-dimensional landmark coordinates were recorded on preoperative computed tomography images of children diagnosed with coronal nonsyndromic craniosynostosis (N = 40) and that of unaffected individuals (N = 20) and analyzed by geometric morphometrics. Our results showed that the fusion pattern of the coronal suture is similar across individuals and types of coronal craniosynostosis. Shape analysis showed that skulls of bilateral coronal craniosynostosis (BCS) and unaffected individuals display low degrees of asymmetry, whereas right and left unilateral coronal craniosynostosis (UCS) skulls are asymmetric and mirror images of one another. When premature fusion of the coronal suture (without taking into account cranial dysmorphology) is scored as a qualitative trait, the expected relationship between trait frequency and trait unilateral expression (i.e. negative correlation) is confirmed. Overall, we interpret our results as evidence that the same biological processes operate on the two sides in BCS skulls and on the affected side in UCS skulls, and that coronal craniosynostosis is a quantitative trait exhibiting a phenotypic continuum with BCS displaying more intense shape changes than UCS. J. Exp. Zool. (Mol. Dev. Evol.) 318:109–122, 2012. © 2011 Wiley Periodicals, Inc.