[Abstrcat] Objectives To analyze 3 cases of 17q12 microdeletion syndrome diagnosed prenatally, and to demonstrate clinical phenotype of the syndrome in prenatal setting.Methods From January 2013 to July 2017,1 370 women received invasive prenatal diagnosis and chromosome microarray analysis(CMA)in Peking Union Medical College Hospital. Among them, 3 fetuses were diagnosed as 17q12 microdeletion syndrome.All 3 cases were low-risk pregnancies.Abnormal structures in fetal kidney were found in all 3 cases, including 1 case of multiple renal cysts,2 cases of bilateral hyperechogenic kidneys.These women accepted invasive prenatal diagnosis followed by karyotyping, parental fluorescence in situ hybridization or CMA validation.Results The second and third trimester ultrasound showed that all 3 fetuses had bilateral renal structural abnormalities, including hyperechogenic kidney, multiple cysts and renal pelvis dilatation. The karyotyping of the 3 fetuses were normal.CMA examination showed that each case had 1.4-1.6 Mb deletion in 17q12 region.Two cases were de novo deletion and 1 case was inherited from the mother who had mild symptoms. The 3 women decided to terminate pregnancies after genetic counseling. Conclusion 17q12 microdeletion syndrome is a recurrent chromosome microdeletion syndrome, and the unique phenotype in prenatal setting is the abnormal structure of bilateral kidneys.A few cases of 17q12 microdeletion syndrome even inherited normally phenotypical parents, and prenatal genetic counseling of 17q12 microdeletion syndrome is relatively difficult.