Widening the mutation spectrum of EVC and EVC2: Ectopic expression of Weyer variants in NIH 3T3 fibroblasts disrupts hedgehog signaling

Autosomal recessive Ellis-van Creveld syndrome and autosomal dominant Weyer acrodental dysostosis are allelic conditions caused by mutations in EVC or EVC2.We performed a mutation screening study in 36 EvC cases and 3 cases of Weyer acrodental dysostosis, and identified pathogenic changes either in EVC or in EVC2 in all cases. We detected 40 independent EVC/EVC2 mutations of which 29 were novel changes in Ellis-van Creveld cases and 2 were novel mutations identified in Weyer pedigrees. Of interest one EvC patient had a T > G nucleotide substitution in intron 7 of EVC (c.940-150T4G), which creates a new donor splice site and results in the inclusion of a new exon. The T > G substitution is at nucleotide 15 of the novel 5′ splice site. The three Weyer mutations occurred in the final exon of EVC2 (exon 22), suggesting that specific residues encoded by this exon are a key part of the protein. Using murine versions of EVC2 exon 22 mutations we demonstrate that the expression of a Weyer variant, but not the expression of a truncated protein that mimics an Ellis-van Creveld syndrome mutation, impairs Hedgehog signal transduction in NIH 3T3 cells in keeping with its dominant effect. © 2009 Wiley-Liss, Inc.