The most notable syndrome with dentin malformations as a phenotype is osteogenesis imperfecta (OI), which affects one in 15,000–20,000 births, with over 85% of cases being autosomal dominant OI types I-IV, caused by defects in COL1A1 and COL1A2, encoding type I collagen [27,28]. The gene discussed is COL1A2; the disease is osteogenesis imperfecta.