CHD1L and familial atrioventricular septal defect: In our study, one patient (No. 191252) was diagnosed as complete AVSD with 1.2 Mb 1q21.1 deletion encompassing 16 genes including known CHD risk genes APC6, BCL9, CHD1L, FM O 5, PRKAB2 and GJA5 (Tomita-Mitchell et al., 2012).