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BioMed Research International
Volume 2018, Article ID 1573871, 9 pages
Review Article

Zone of Polarizing Activity Regulatory Sequence Mutations/Duplications with Preaxial Polydactyly and Longitudinal Preaxial Ray Deficiency in the Phenotype: A Review of Human Cases, Animal Models, and Insights Regarding the Pathogenesis

King Saud University, Riyadh, Saudi Arabia

Correspondence should be addressed to Mohammad M. Al-Qattan; moc.liamtoh@nattaqom

Received 9 October 2017; Revised 19 December 2017; Accepted 16 January 2018; Published 13 February 2018

Academic Editor: Thomas Lufkin

Copyright © 2018 Mohammad M. Al-Qattan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Clinicians and scientists interested in developmental biology have viewed preaxial polydactyly (PPD) and longitudinal preaxial ray deficiency (LPAD) as two different entities. Point mutations and duplications in the zone of polarizing activity regulatory sequence (ZRS) are associated with anterior ectopic expression of Sonic Hedgehog (SHH) in the limb bud and usually result in a PPD phenotype. However, some of these mutations/duplications also have LPAD in the phenotype. This unusual PPD-LPAD association in ZRS mutations/duplications has not been specifically reviewed in the literature. The author reviews this unusual entity and gives insights regarding its pathogenesis.