In addition, we found significant differences in MMP3 rs520540 A/G genotype frequency (p = 0.049) and allele frequency (p = 0.016) as well as MMP3 rs679620 T/C genotype frequency (p = 0.033) and allele frequency (p = 0.012) between CS patients and healthy controls (Fig. 2). This evidence concerns the gene MMP3 and Cowden syndrome 1.