MATN3 and multiple epiphyseal dysplasia type 5: Therefore, in order to further understand the role of XBP1 signalling in the protein aggregation and disease pathology of Matn3-related MED we crossed a p.V194D knock-in mouse model of EDM5 with a mouse line carrying a cartilage specific deletion of Xbp1 and analysed in-depth the resulting phenotype.