ZBTB21 and familial atrioventricular septal defect: They examined embryos at E14.5 using high-resolution episcopic microscopy (HREM) and found that 61.5% of the Dp1Tyb (carrying a duplication of 148 genes between Lipi-Zbtb21 similar to the Dp16 mice) and 44% in the Dp3Tyb (carrying a duplication of 40 genes between Mir802-Zbtb21) present with heart defects, including AVSD, VSD and ASD.