The molecular mechanism of Cleidocranial dysplasia (CCD) related to Runx2 haploinsufficiency involves the activated FGF signalling by freely excessive unbound Twist1.114 Besides, FAM20B is a xylose kinase that is required for glycosaminoglycan (GAG) assembly. The gene discussed is FAM20B; the disease is cleidocranial dysplasia 1.