Prenatal Diagnosis, Ultrasound Findings, and Follow-up Information of 1q21.1 Deletion and Duplication Syndromes: A Single-Center Case Series

Objective: This research seeks to perform an initial evaluation of the association between prenatal phenotypes and 1q21.1 deletion/duplication syndrome. Methods: A retrospective analysis was performed on 16 cases diagnosed with 1q21.1 deletions and 13 cases with 1q21.1 duplications, employing single nucleotide polymorphism arrays (SNP arrays). This study encompassed an examination of ultrasound abnormalities, parental verification, pregnancy outcomes, and postnatal follow-up data. Results: The deletions fragment sizes of the 16 deletion cases ranged from 1.30 Mb to 2.18 Mb, with the overlapping region located at 146.5 Mb to 147.5 Mb. The fragment sizes of the 13 duplication cases ranged from 0.87 Mb to 3.87 Mb, with the overlapping region located at 146.5 Mb to 147.0 Mb. Among the 16 fetuses with deletions, eight exhibited ultrasound-detected abnormalities. Specifically, three fetuses had urinary tract malformations, four were diagnosed with fetal growth retardation, three displayed lateral ventricle enlargement, and one had aortic stenosis. Notably, Case 12 demonstrated a unique presentation of complex multi-organ malformations, including fetal growth retardation, absence of the right kidney, micrognathia, and lateral ventricle enlargement. Of the 13 fetuses with duplication, six were found to have ultrasound abnormalities, including four fetuses with cardiovascular malformations, one fetus with fetal growth retardation, one fetus with widened posterior fossa, and one fetus with widened lateral ventricle. Case 22 is particularly special, as the fetus has complex cardiac malformations, including pulmonary stenosis, aorta displacement, and ventricular septal defect. Conclusion: This study suggests that fetuses with prenatal 1q21.1 deletions may be associated with malformations of the urinary system, whereas those with 1q21.1 duplications are likely associated with cardiac malformations. Nonetheless, both genetic conditions demonstrate a lack of phenotypic specificity. For fetuses diagnosed with 1q21.1 deletions or duplications who present with a normal phenotype prenatally, it is essential to conduct close monitoring of their neurodevelopmental trajectory postnatally.