Moreover, a combined phenotype of HHT and Juvenile Polyposis is recognized as the JPHT syndrome, related to mutations in MADH4 gene (18q21.1; OMIM*600993), coding for SMAD4, the common mediator of TGF-β/BMPs signalling, involved in transcriptional activation of as yet unidentified target genes [17]. This evidence concerns the gene SMAD4 and hereditary hemorrhagic telangiectasia.