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 3-M syndrome.