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

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.

• Authors: Jacob W P Potuijt, Martijn Baas, Rivka Sukenik-Halevy, Hannie Douben, Picard Nguyen, Deon J Venter, Renée Gallagher, Sigrid M Swagemakers, Steven E R Hovius, Christianne A van Nieuwenhoven, Robert-Jan H Galjaard, Peter J van der Spek, Nadav Ahituv, Annelies de Klein
• Journal: Genetics in medicine : official journal of the American College of Medical Genetics (Genet Med) Vol. 20 Issue 11 Pg. 1405-1413 (11 2018) ISSN: 1530-0366 [Electronic] United States
• PMID: 29543231 (Publication Type: Journal Article)

Chemical References

• Hedgehog Proteins
• LMBR1 protein, human
• Membrane Proteins
• SHH protein, human

Topics

• Animals
• Chromosomes, Human, Pair 7 (genetics)
• Congenital Abnormalities (genetics)
• Enhancer Elements, Genetic (genetics)
• Female
• Gene Expression Regulation (genetics)
• Genetic Linkage
• Genetic Predisposition to Disease
• Hedgehog Proteins (genetics)
• Humans
• In Situ Hybridization, Fluorescence
• Limb Buds (physiopathology)
• Male
• Mandibulofacial Dysostosis (genetics)
• Membrane Proteins (genetics)
• Mice
• Pedigree
• Point Mutation (genetics)
• Polymorphism, Single Nucleotide
• Exome Sequencing