Objective: Dupuytren disease (DD) is a polygenic fibroproliferative disorder of the palmar fascia of the hand. Building on our previous work, we aimed to further characterize the genetic predisposition to DD by performing a genome-wide association study (GWAS) on a total of 7934 DD cases and 12°861 controls from the United Kingdom, Holland, and Germany. We then aimed to dissect the functional effects of the statistically associated variant within DD-derived myofibroblasts. Materials and Methods: We extracted DNA from saliva or blood of DD patients who had undergone fasciectomy or dermofasciectomy. The genotypes of each sample were investigated using Illumina HumanExomeCore microarray chips in the discovery phase, and other platforms for replication phase. For our functional analysis, we used single-gene TaqMan assays to measure messenger RNA (mRNA) expression of myofibroblast cells that were disaggregated from DD nodules. Primary myofibroblasts were stimulated with a combination of recombinant WNT3A, SFRP4, and DKK1 proteins for 48 hours, and mRNA expression was measured. Results: Our GWAS meta-analysis revealed a total of 24 DD-associated regions, 15 of which were novel (P < 5 × 10−8). We observed a 4-fold difference in SFRP4 mRNA expression between the 2 homozygous genotypes of our most associated single-nucleotide polymorphism rs1687975. Interestingly, an inverse correlation was observed in extracellular SFRP4 protein secretion. Our WNT signaling pathway stimulation experiments demonstrated that SFRP4 attenuates WNT3A-induced connective tissue growth factor (CTGF) expression, showing a 20% decrease (P < .05). SFRP4 alone has no effect on alpha-smooth muscle actin, COL1A1, and COL3A1 mRNA expression. Conclusions: We have performed a large 3-stage GWAS and have discovered 15 novel Dupuytren-associated regions. We have identified that our most significantly associated variant, rs16879765, has an effect on the mRNA expression of a WNT antagonist gene SFRP4. Further functional analysis on SFRP4 has revealed that it affects the expression of CTGF. This implies its anti-fibrotic effect is mediated by the non-canonical WNT signaling pathway, potentially via the YAP/TAZ pathway that is known to interact with transforming growth factor β (TGF BETA) pathway, and this plays a critical role in the development of DD. Our GWAS has also revealed multiple potential new therapeutic targets for DD. Genes within the associated regions include MMP14 and WNT4 and have effects on diverse functions such as inflammation, extracellular matrix remodeling, cellular differentiation, and proliferation, which are likely to be important processes in the development of DD and fibrotic diseases in general.
