To date, at least 20 genes with autosomal dominant or recessive inheritance pattern have been recognized to be responsible for OI, including COL1A1, COL1A2, BMP1, SERPINF1, SERPINH1, CRTAP, P3H1, PPIB, TMEM38B, WNT1, FKBP10, PLOD2, IFITM5, MBTPS2, CREB3L1, SP7, SPARC, P4HB, PLS3, and SEC24D [1], of which the COL1A1/2 (MIM *120150/120160) associated subtypes account for ~90% cases [2]. The gene discussed is COL1A2; the disease is osteogenesis imperfecta.