OBJECTIVE: To report a rare 17q12 microduplication family. CASE REPORT: A 29-year-old woman (gravida 1, para 0) underwent amniocentesis at 21 weeks' gestation because of double bubble sign and polyhydramnios of the fetus on prenatal ultrasound. Chromosomal microarray analysis (CMA) from this family revealed a 1.78-Mb microduplication on chromosome 17q12 of the fetal, spanning from position 34,460,444 to 36,243,365 (GRCh37). Trio whole-exome sequencing (WES) showed 17q12 microduplication in the fetal and the mother. After genetic counselling and being informed of the unfavourable prognosis, the parents decided to continue the pregnancy. CONCLUSION: We provide a detailed description of the phenotype in a rare family with 17q12 microduplication. Combination of karyotype analysis, CMA, WES, prenatal ultrasound and genetic counseling is helpful for the prenatal diagnosis of chromosomal microdeletions/microduplications.