Prenatal detection of distal 1q21.1q21.2 microduplication with abnormal ultrasound findings: Two cases report and literature review

RATIONALE: 1q21.1 duplication is an uncommon chromosomal submicroscopic imbalance which is associated with growth/mental retardation, dysmorphic features, autism, multiple congenital and neuropsychiatric disorders. PATIENT CONCERNS: Two pregnant women underwent amniocentesis for cytogenetic analysis and chromosomal microarray analysis (CMA) following abnormal ultrasound findings. Case 1 presented short nasal bone and case 2 showed absent nasal bone, ventricular septal defect and umbilical cord circling in ultrasonic examination. DIAGNOSES: G-banding analysis showed that the two fetuses presented normal karyotypic results while CMA detected 1.796 Mb (case 1) and 1.242 Mb (case 2) microduplications in the region of 1q21.1q21.2 separately. Furthermore, the CMA also revealed a 1.2 Mb microdeletion of 8p23.3 in case 1. INTERVENTIONS: The couple in case 1 chose to terminate the pregnancy, while the couple in case 2 continued the pregnancy and finally delivered a male infant who presented low nasal bridge and ventricular septal defect. OUTCOMES: The 1q21.1q21.2 duplications in our report were located in the distal 1q21.1 region, overlapping with 1q21.1 duplication syndrome. Case 2 was the first reported live birth with 1q21.1 duplication according to prenatal CMA detection in China. LESSONS: The genotype-phenotype of 1q21.1 duplication is complicated due to the phenotypic diversity, incomplete penetrance, and lack of obvious characteristics. So it is difficult to predict the postnatal development and health conditions clinically. Hence, long term follow up is necessary for newborn infants with 1q21.1 duplication, irrespective of whether the duplication is de novo or inherited.