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Background Copy number variations represent a key source of genomic variability, encompassing both benign and pathogenic alterations. Accurate interpretation of copy number variations identified through prenatal screening is critical for effective genetic consultation and clinical management. Microdeletions within the 16q24.3 locus remain understudied, thereby complicating genetic counseling for affected cases. Case presentation: This study describes the prenatal diagnostic workup and genetic counseling process for a Chinese family with a fetus carrying a de novo 16q24.3 microdeletion. Conclusion Conventional cytogenetic techniques exhibit limited sensitivity for the detection of chromosomal microdeletions and microduplications. A multimodal approach integrating prenatal ultrasound, karyotyping, chromosomal microarray analysis, and genetic counseling enhances the diagnostic accuracy of such chromosomal anomalies during pregnancy.

Background Copy number variants (CNVs) represent a significant source of genomic diversity, encompassing both benign and pathogenic variations. The accurate interpretation of CNVs identified during prenatal diagnosis is crucial for appropriate genetic counseling and management. The literature on 5p13.3p13.2 microduplication is rare, which is a challenge for genetic counseling. Materials and methods A 35-year-old, gravida 2, para 1, woman underwent amniocentesi at 18 weeks of gestation due to advanced maternal age. We performed conventional karyotyping, chromosomal microarray analysis (CMA) and quartet whole-exome sequencing (WES) on this family. Results We report a case of prenatal diagnosis and genetic counseling of a paternally inherited 5p13.3p13.2 microduplication. In this family, both the father and the fetus carry the identical microduplication yet exhibit a normal phenotype. Conclusion Submicroscopic chromosomal microdeletions and microduplications are often undetectable by conventional cytogenetics. The integration of prenatal ultrasound, karyotyping, CMA, and WES is therefore essential for accurate diagnosis.

Background Patients with deletions involving the long arm of chromosome 1 are rare. The PBX1 gene is located on chromosome 1q23.3. PBX1 encodes a transcription factor which promotes protein–protein interaction and plays a crucial role in several developmental processes. PBX1 haploinsufficiency had been reported to lead syndromic congenital anomalies of kidney and urinary tract (CAKUT) in humans. Case presentation In this research, a 24-year-old woman (gravida 1, para 0) underwent amniocentesis at 22 weeks’ gestation because of a horseshoe kidney of the fetus on prenatal ultrasound. Results Chromosomal microarray analysis (CMA) from this family revealed a 1.14 Mb paternal inherited deletion on chromosome 1q23.3, spanning from position 163,620,000 to 164,760,000 (hg19). Trio whole-exome sequencing (WES) showed heterozygous deletions in exons 1–2 of the PBX1 in fetal and paternal samples. At the 3-year follow-up, the baby did not have an abnormal phenotype except a horseshoe kidney. Conclusion We provide a detailed description of the phenotype in a family with paternal inherited deletion of 1q23.3 encompassing exons 1–2 of the PBX1 gene. Combination of karyotype analysis, CMA, WES, prenatal ultrasound and genetic counseling is helpful for the prenatal diagnosis of chromosomal microdeletions/microduplications.

Background Proximal region of chromosome 15 long arm is rich in duplicons that, define five breakpoints (BP) for 15q rearrangements. 15q11.2 microdeletion has been previously associated with developmental delay, mental retardation, epilepsy, autism, schizophrenia and congenital heart defects. The literature on this microdeletion is extensive and confusing, which is a challenge for genetic counselling. Case presentation We have performed prenatal diagnosis and genetic counseling of a paternally inherited 15q11.2 microdeletion. In this family, father with normal phenotype and fetus with abnormal phenotype have the same microdeletion. Conclusion Chromosomal microdeletions and microduplications are difficult to detect by conventional cytogenetics, combination of prenatal ultrasound, karyotype analysis, CMA and genetic counseling is helpful for the prenatal diagnosis of chromosomal microdeletions/microduplications.

Background Unbalanced chromosome abnormalities (UBCA) are either gains or losses or large genomic regions, but the affected person is not or only minimally clinically affected. Copy number variants (CNVs) are an important source of normal and pathogenic genome variations. CNVs and UBCA identified in prenatal cases need careful considerations and correct interpretation if those are harmless or harmful variants from the norm. Case presentation A 25-year-old, gravida 1, para 0, woman underwent amniocentesis at 18 weeks of gestation because the noninvasive prenatal testing (NIPT) results revealed a 6.8 Mb duplication from 2q11.1 to 2q11.2. Chromosomal microarray analysis (CMA) was performed on uncultured amniocytes. GTG-banding karyotype analysis on cultured amniocytes was performed. Results Chromosomal GTG-banding of the cultured amniocytes revealed a karyotype of 46,XX. CMA detected a 6.8-Mb chromosomal duplication in the region of 2q11.1q11.2 (arr[GRCh37] 2q11.1q11.2(95,327,873_102,088,148)x3). Conclusion Chromosomal microdeletions and microduplications are difficult to detect by conventional cytogenetics, combination of prenatal ultrasound, karyotype analysis, NIPT, CMA and genetic counseling is helpful for the prenatal diagnosis of UBCA and chromosomal microdeletions/microduplications.

Purpose The aim of this study was to assess the detection efficiency and clinical application value of non-invasive prenatal testing (NIPT) for foetal copy number variants (CNVs) in clinical samples from 39,002 prospective cases. Methods A total of 39,002 pregnant women who received NIPT by next-generation sequencing (NGS) with a sequencing depth of 6 M reads in our centre from January 2018 to April 2020 were enrolled. Chromosomal microarray analysis (CMA) was further used to diagnose suspected chromosomal aneuploidies and chromosomal microdeletion/microduplication for consistency assessment. Results A total of 473 pregnancies (1.213%) were positive for clinically significant foetal chromosome abnormalities by NIPT. This group comprised 99 trisomy 21 (T21, 0.254%), 30 trisomy 18 (T18, 0.077%), 25 trisomy 13 (T13, 0.064%), 155 sex chromosome aneuploidy (SCA, 0.398%), 69 rare trisomy (0.177%), and 95 microdeletion/microduplication syndrome (MMS, 0.244%) cases. Based on follow-up tests, the positive predictive values (PPVs) for the T21, T18, T13, SCA, rare trisomy, and MMS cases were calculated to be 88.89%, 53.33%, 20.00%, 40.22%, 4.88%, and 49.02%, respectively. In addition, the PPVs of CNVs of < 5 Mb, 5–10 Mb, and > 10 Mb were 54.55%, 38.46%, and 40.00%, respectively. Among the 95 cases with suspected CNVs, 25 were diagnosed as true positive and 26 cases as false positive; follow-up prenatal diagnosis by CMA was not performed for 44 cases. Moreover, among the 25 true positive cases, 10 were pathogenic, 3 were likely pathogenic, and 12 were of uncertain significance. Conclusion NIPT is not only suitable for screening T21, T18, T13, and SCA but also has potential significance for CNV detection. As combined with ultrasound, extended NIPT is effective for screening MMS. However, NIPT should not be recommended for whole-chromosome aneuploidy screening.

Background To evaluate the accuracy and feasibility of noninvasive prenatal testing (NIPT) according to the results of NIPT and pregnancy outcomes with different indications. Methods Between October 2014 and December 2020, 20,626 pregnant women who received NIPT were included in this study. The positive predictive value (PPV) of trisomy 21, 18, and 13 (T21, T18, T13), sex chromosome abnormalities (SCAs), other chromosomal aneuploidies, and chromosomal microdeletion/microduplication were calculated. The positive results of NIPT were confirmed by amniocentesis, Karyotype analysis, and chromosome microarray analysis (CMA). Results In total, 263 positive cases (263/20,626, 1.28%) were detected by NIPT, of which T21, T18, and T13 were 69, 26, and 9 cases, respectively. Sex chromosome abnormalities (SCAs), other chromosomal aneuploidies, and copy number variants (CNVs) were 69, 12, and 38 cases, respectively. There were true positive in 49 of T21, 13 of T18, 1 of T13, 32 of SCAs, 1 of other chromosomal aneuploidies, and 15 of CNVs. The NIPT sensitivity of T21, T18, T13, SCAs, other chromosomal aneuploidies, and CNVs was all 100%, the specialty was 99.90%, 99.94%, 99.96%, 99.82%, 99.95%, 99.89%, and the PPV was 71.01%, 50.00%, 11.11%, 46.38%, 8.33%, 39.47%, respectively. The PPV was high in T21, moderate in T18 and SCAs, and low in T13 and other chromosomal abnormalities. Conclusion NIPT has high accuracy, specificity and and can effectively avoid the occurrence of birth defects, but it cannot replace prenatal diagnosis. The accuracy, specificity, and sensitivity of NIPT in detecting sex chromosomes, chromosome microdeletion/microduplication, and other chromosomal abnormalities should be improved. Noninvasive detection process to detect fetal free DNA in maternal plasma samples.

Background Chromosome rearrangements are frequently observed in the Xp22.31 region. Xp22.31 microdeletion is linked to X-linked ichthyosis, whereas the pathogenicity of Xp22.31 microduplication remains a subject of controversy. In the present study, 52 additional foetuses with Xp22.31 microdeletions/microduplications were presented, with the aim of providing further insights into the prenatal diagnosis and genetic counselling of Xp22.31 microdeletions/microduplications. Methods A retrospective analysis was conducted involving a total of 4,251 pregnant women who received amniocentesis of prenatal diagnosis in our hospital from January 2017 to August 2022. All of the subjects were subjected to karyotype and chromosomal microarray analysis (CMA) for evaluation of chromosomal abnormalities. Whole exome sequencing (WES) was subsequently employed to explore additional variants in individuals presenting unexplained clinical features. Results Among the enrolled subjects, a total of 52 cases with Xp22.31 microdeletions/microduplications were detected using CMA, with a detection rate of 1.22% (52/4251). A total of 35 foetuses carried Xp22.31 microduplications and most of them exhibited normal developmental milestone after birth, except one case with motor and speech developmental delay. Additionally, 17 foetuses harbored Xp22.31 microdeletions, 10 male foetuses exhibited ichthyosis after birth, 6 female foetuses manifested normal clinical features, and the remaining were terminated based on parental request. In the present study, WES was further conducted on a foetus with renal abnormalities; however, no likely pathogenic or pathogenic variants in genes related to the observed phenotype were identified. Conclusions The present authors propose that Xp22.31 microduplication may be a benign copy number variant. In addition, the findings reveal, for the first time, a previously unknown association between renal agenesis and Xp22.31 microdeletion, thus expanding the range of clinical manifestations associated with Xp22.31 microdeletions.

This article reviews the current applications of the digital polymerase chain reaction (dPCR) in non-invasive prenatal testing (NIPT) and explores its potential to complement or surpass the capabilities of Next-Generation Sequencing (NGS) in prenatal testing. The growing incidence of genetic disorders in maternal–fetal medicine has intensified the demand for precise and accessible NIPT options, which aim to minimize the need for invasive prenatal diagnostic procedures. Cell-free fetal DNA (cffDNA), the core analyte in NIPT, is influenced by numerous factors such as maternal DNA contamination, placental health, and fragment degradation. dPCR, with its inherent precision and ability to detect low-abundance targets, demonstrates robustness against these interferences. Although NGS remains the gold standard due to its comprehensive diagnostic capabilities, its high costs limit widespread use, particularly in resource-limited settings. In contrast, dPCR provides comparable accuracy with lower complexity and expense, making it a promising alternative for prenatal testing.

ObjectiveChromosomal 1q21.1 deletions and duplications are genomic disorders that are usually diagnosed postnatally. However, the genotype–phenotype correlations of 1q21.1 copy number variants (CNVs) during the prenatal period are still not clear. This study aimed to provide a systematic summary of prenatal phenotypes for such genomic disorders.MethodsIn total, 26 prenatal amniotic fluid samples diagnosed with 1q21.1 microdeletions/microduplications were obtained from pregnant women who opted for invasive prenatal testing. Karyotypic analysis and chromosomal microarray analysis (CMA) were performed for all cases simultaneously. The pregnancy outcomes and health conditions after birth in all cases were followed up. Meanwhile, prenatal cases with 1q21.1 microdeletions or microduplications in the literature were retrospectively collected.ResultsIn total, 11 pregnancies (11/8,252, 0.13%) with 1q21.1 microdeletions and 15 (15/8,252, 0.18%) with 1q21.1 microduplications were identified. Among these 1q21.1 CNVs, 4 cases covered the thrombocytopenia-absent radius (TAR) region, 16 cases covered the 1q21.1 recurrent microdeletion/microduplication region, and 6 cases covered all regions mentioned above. The prenatal abnormal ultrasound findings were recorded in four participants with 1q21.1 deletions and seven participants with 1q21.1 duplications. Finally, three cases with 1q21.1 deletions and five with 1q21.1 duplications terminated their pregnancies.ConclusionIn the prenatal setting, 1q21.1 microdeletions were associated with increased nuchal translucency (NT), anomalies of the urinary system, and cardiovascular abnormalities, while 1q21.1 microduplications were correlated with cardiovascular malformations, nasal bone dysplasia, and increased NT. In addition, cerebral ventriculomegaly might be correlated with 1q21.1 microduplications. Considering the variable expressivity and incomplete penetrance of 1q21.1 CNVs, long-term follow-up after birth should be carried out in these cases.