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.

Objective:To identify the genetic causes of adverse pregnancy outcomes in five families and provide a basis for rational guidance on genetic and reproductive counseling.Methods:A retrospective analysis was conducted on five families with a history of adverse pregnancy outcomes, where one partner was found to have a cryptic balanced translocation. These cases were identified among pregnant women who underwent invasive prenatal diagnosis at the Department of Medical Genetics and Prenatal Diagnosis, Wuxi Maternity and Child Health Care Hospital, from January 2016 to June 2023. Conventional G-banding karyotyping and chromosomal microarray analysis (CMA) were performed on affected children/fetus samples. Chromosome G-banding and fluorescence in situ hybridization (FISH) were used for parental tracing. Genetic counseling was provided for all cases, and the pregnancy outcomes were followed up. Descriptive analysis was applied in this study. Results:Case 1 involved an eldest son with unexplained intellectual disability, and the CMA results showed an 8.6 Mb deletion in the 4p16.3p16.1 region and a 1.0 Mb duplication in the 7q36.3 region. Unbalanced translocations were detected in the current pregnancies of the other four cases, which were a 6.1 Mb duplication in the 14q32.2q32.33 region with a 1.6 Mb deletion in the 21q22.3 region (Case 2), a 10.8 Mb duplication in the 6q25.3q27 region with a 1.2 Mb deletion in the 15q26.3 region (Case 3), a 1.0 Mb duplication in the 5p15.33 region with a 2.9 Mb deletion in the 6q27 region (Case 4), and a 3.2 Mb deletion in the 1q44 region with a 4.8 Mb duplication in the 19p13.3 region (Case 5). FISH confirmed that either the husband or the wife in each of the five families was a carrier of a cryptic balanced translocation. Further CMA testing on amniotic fluid samples from previous terminated pregnancies of Cases 3 and 4 also indicated unbalanced translocations. Both the current pregnancy of Case 1 and the subsequent pregnancy of Case 2 gave birth to healthy babies after non-abnormal prenatal diagnosis and genetic counseling. Cases 3 to 5 are currently preparing for pregnancy.Conclusion:Advances and combined application of genetic technologies will be conducive to improving the diagnosis of cryptic balanced translocations in some families with adverse pregnancy outcomes, providing a sound basis for genetic counseling in future pregnancy.