A point mutation in the pre-ZRS disrupts sonic hedgehog expression in the limb bud and results in triphalangeal thumb-polysyndactyly syndrome

Authors

Jacob W. P Potuijt, University Medical Center Rotterdam
Martijn Baas, University Medical Center Rotterdam
Rivka Sukenik-Halevy, University of California San Francisco, Tel-Aviv University
Hannie Douben, University Medical Center Rotterdam
Picard Nguyen, University Medical Center Rotterdam
Deon J. Venter, University of Wollongong, Mater Health Services, Royal Prince Alfred HospitalFollow
Renee Gallagher, Mater Health Services
Sigrid M. Swagemakers, University Medical Center Rotterdam
Steven E. R Hovius, University Medical Center Rotterdam
Christianne A. van Nieuwenhoven, University Medical Center Rotterdam
Robert-Jan H. Galjaard, University Medical Center Rotterdam
Peter J. van der Spek, University Medical Center Rotterdam
Nadav Ahituv, University of California San Francisco
Annelies de Klein, University Medical Center Rotterdam

RIS ID

132360

Publication Details

Potuijt, J. W. P., Baas, M., Sukenik-Halevy, R., Douben, H., Nguyen, P., Venter, D. J., Gallagher, R., Swagemakers, S. M., Hovius, S. E. R., van Nieuwenhoven, C. A., Galjaard, R. H., van der Spek, P. J., Ahituv, N. & de Klein, A. (2018). A point mutation in the pre-ZRS disrupts sonic hedgehog expression in the limb bud and results in triphalangeal thumb-polysyndactyly syndrome. Genetics in Medicine, 20 (11), 1405-1413.

Abstract

Purpose: The zone of polarizing activity regulatory sequence (ZRS) is an enhancer that regulates sonic hedgehog during embryonic limb development. Recently, mutations in a noncoding evolutionary conserved sequence 500 bp upstream of the ZRS, termed the pre-ZRS (pZRS), have been associated with polydactyly in dogs and humans. Here, we report the first case of triphalangeal thumb-polysyndactyly syndrome (TPT-PS) to be associated with mutations in this region and show via mouse enhancer assays how this mutation leads to ectopic expression throughout the developing limb bud.

Methods: We used linkage analysis, whole-exome sequencing, Sanger sequencing, fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, single-nucleotide polymorphism array, and a mouse transgenic enhancer assay.

Results: Ten members of a TPT-PS family were included in this study. The mutation was linked to chromosome 7q36 (LOD score 3.0). No aberrations in the ZRS could be identified. A point mutation in the pZRS (chr7:156585476G>C; GRCh37/hg19) was detected in all affected family members. Functional characterization using a mouse transgenic enhancer essay showed extended ectopic expression dispersed throughout the entire limb bud (E11.5).

Conclusion: Our work describes the first mutation in the pZRS to be associated with TPT-PS and provides functional evidence that this mutation leads to ectopic expression of this enhancer within the developing limb.