Other downregulated genes identified which could potentially be implicated in the pathogenesis of 3-M syndrome included LGR5 (a member of the G-protein-coupled receptor superfamily) and COL4A1 (the main component of type IV collagen which forms basement membrane); silencing of expression of these genes is associated with decreased cell proliferation (49) while in tumours (50, 51), they have been found to be upregulated. Here, COL4A1 is linked to 3M syndrome.