RESUMEN
Objective:To explore the clinical phenotypes, pregnancy outcomes, and follow-up of fetuses with 1q21.1 distal microdeletion/microduplication, and to provide a basis for prenatal and genetic counseling.Methods:This was a retrospective study involving 14 singleton fetuses with 1q21.1 distal microdeletion/microduplication that were prenatally diagnosed by karyotype analysis and chromosomal microarray analysis (CMA) at Wuxi Maternity and Child Health Care Hospital from January 2017 to June 2022. The results of ultrasound and genetic analysis, pregnancy outcome after genetic counseling, and postnatal follow-up were summarized using descriptive statistical methods.Results:All 14 fetuses had normal karyotypes. Out of the 14 cases, CMA indicated 1q21.1 distal microdeletion in eight cases and 1q21.1 distal microduplication in six cases. The fragments ranged from 813 kb to 4.48 Mb, all of which contained the key region of 1q21.1 microdeletion/microduplication syndrome and were pathogenic copy number variations (CNV). Among eight fetuses with distal 1q21.1 microdeletion, four cases had abnormal prenatal ultrasound findings, including one case with overlapping fingers of left hand and polyhydramnios, two were small for gestational age, and one with small head circumference. Among the six cases who underwent parental origin detection, the microdeletions were de novo in four fetuses and two fetuses were inherited from the parent with normal phenotype. As for six fetuses with distal 1q21.1 microduplication, nasal bone absence or hypoplasia was shown by ultrasound in four cases and no obvious abnormality was found in the other two cases. Parental origin detection was performed in four cases, which found that one case was de novo and the other three cases were inherited from their phenotypically normal parents. After genetic counseling, five families chose to terminate the pregnancies and the remaining nine cases continued the pregnancies to delivery. The last follow-up showed that all of the nine live births grew well, whose ages ranged from seven months to half past five years old. Conclusions:CMA is of great value in prenatal diagnosis of 1q21.1 distal microdeletion/ microduplication. Ones carrying pathogenic CNV may not develop the disease. Combined with ultrasound findings and parental genetic tracing results, individualized genetic counseling and long-term follow-up are of great importance for reasonable guidance in pregnancy outcome and reproduction.