Single-cell RNA sequencing reveals cellular and molecular landscape of fetal cystic hygroma

BACKGROUND

The molecular mechanism of fetal cystic hygroma (CH) is still unclear, and no study has previously reported the transcriptome changes of single cells in CH. In this study, single-cell transcriptome sequencing (scRNA-seq) was used to investigate the characteristics of cell subsets in the lesion tissues of CH patients.

METHODS

Lymphoid tissue collected from CH patients and control donors for scRNA-seq analysis. Differentially expressed gene enrichment in major cell subpopulations as well as cell-cell communication were analyzed. At the same time, the expression and interactions of important VEGF signaling pathway molecules were analyzed, and potential transcription factors that could bind to KDR (VEGFR2) were predicted.

RESULTS

The results of scRNA-seq showed that fibroblasts accounted for the largest proportion in the lymphatic lesions of CH patients. There was a significant increase in the proportion of lymphatic endothelial cell subsets between the cases and controls. The VEGF signaling pathway is enriched in lymphatic endothelial cells and participates in the regulation of cell-cell communication between lymphatic endothelial cells and other cells. The key regulatory gene KDR in the VEGF signaling pathway is highly expressed in CH patients and interacts with other differentially expressed EDN1, TAGLN, and CLDN5 Finally, we found that STAT1 could bind to the KDR promoter region, which may play an important role in promoting KDR up-regulation.

CONCLUSION

Our comprehensive delineation of the cellular composition in tumor tissues of CH patients using single-cell RNA-sequencing identified the enrichment of lymphatic endothelial cells in CH and highlighted the activation of the VEGF signaling pathway in lymphoid endothelial cells as a potential modulator. The molecular and cellular pathogenesis of fetal cystic hygroma (CH) remains largely unknown. This study examined the distribution and gene expression signature of each cell subpopulation and the possible role of VEGF signaling in lymphatic endothelial cells in regulating the progression of CH by single-cell transcriptome sequencing. The enrichment of lymphatic endothelial cells in CH and the activation of the VEGF signaling pathway in lymphatic endothelial cells provide some clues to the pathogenesis of CH from the perspective of cell subpopulations.

Prenatal diagnosis and outcomes in fetuses with duplex kidney

OBJECTIVE

Duplex kidney is a relatively frequent form of urinary system abnormality. This study aimed to elucidate the value of chromosomal microarray analysis (CMA) and whole exome sequencing (WES) for duplex kidney and the perinatal outcomes of duplex kidney fetuses.

METHODS

This retrospective cohort study included 63 patients with duplex kidney diagnosed using antenatal ultrasound between August 2013 and January 2023. We reviewed the clinical characteristics, genetic test results, and pregnancy outcomes of the patients.

RESULTS

Among the 63 cases based on the inclusion criteria, the CMA detected seven (11.1%) clinically significant variants and nine variants of uncertain significance (VUS), and the pathogenic/likely pathogenic (P/LP) copy number variations (CNVs) in the recurrent region that were associated with prenatal duplex kidney included 17q12, 17p13.3, and 22q11.2. No significant disparity was observed in the CMA detection rate between the unilateral and bilateral groups, or between the isolated and non-isolated groups. WES identified three (50%) P/LP single-gene variants in six fetuses with duplex kidney. We detected the following pathogenic genes in the duplex kidney fetuses: KMT2D, SMPD4, and FANCI. Pregnancy termination in cases where clinically significant variants were detected by genetic testing was different in statistical significance from that in cases with negative results (9/10, 90.0% vs 8/48, 16.7%, P < 0.001).

CONCLUSION

This study elucidated the value of CMA and WES for fetal duplex kidney, proving that CMA and WES may be useful tools in prenatal diagnosis and genetic counseling.

Prenatal diagnosis and early childhood outcome of fetuses with extremely large nuchal translucency

OBJECTIVE

To evaluate the prenatal and perinatal outcome of fetuses with extremely large nuchal translucency (eNT) thickness (≥ 6.5 mm).

METHODS

193 (0.61%) singleton fetuses with eNT were retrospectively included. Anomaly scan, echocardiography, and chromosomal and genetic test were included in our antenatal investigation. Postnatal follow-up was offered to all newborns.

RESULTS

Major congenital anomalies included congenital heart defect (32.6%, 63/193), hydrops fetalis (13.5%, 26/193), omphalocele (9.3%, 18/193), and skeletal dysplasia (7.8%, 15/193) et al. Abnormal karyotype was identified in 81/115 (70.4%) cases including Turner syndrome (n = 47), Trisomy 18 (n = 17), Trisomy 21 (n = 9), and Trisomy 13 (n = 3). Chromosomal microarray analysis provided informative results with 3.6% (1/28) incremental diagnostic yield over conventional karyotyping. The diagnostic yield of exome sequencing is 10.0% (2/20). There was no significant increase [Odds Ratio (OR) = 1.974; 95% confidence interval 0.863-4.516; P = 0.104] in the incidence of chromosomal defects despite the presence of other structural anomalies. Only 13 fetuses were successfully followed up and survived at term, no one was found with developmental delay or mental retardation.

CONCLUSIONS

Extremely large NT has a high risk of chromosomal abnormality. CMA and ES improve chromosomal genomic and genetic diagnosis of fetal increased NT. When cytogenetic analysis and morphology assessment are both normal, the outcome is good.

Prenatal diagnosis in the fetal hyperechogenic kidneys: assessment using chromosomal microarray analysis and exome sequencing

Fetal hyperechogenic kidneys (HEK) is etiologically a heterogeneous disorder. The aim of this study was to identify the genetic causes of HEK using prenatal chromosomal microarray analysis (CMA) and exome sequencing (ES). From June 2014 to September 2022, we identified 92 HEK fetuses detected by ultrasound. We reviewed and documented other ultrasound anomalies, microscopic and submicroscopic chromosomal abnormalities, and single gene disorders. We also analyzed the diagnostic yield of CMA and ES and the clinical impact the diagnosis had on pregnancy management. In our cohort, CMA detected 27 pathogenic copy number variations (CNVs) in 25 (25/92, 27.2%) fetuses, with the most common CNV being 17q12 microdeletion syndrome. Among the 26 fetuses who underwent further ES testing, we identified 7 pathogenic/likely pathogenic variants and 8 variants of uncertain significance in 9 genes in 12 fetuses. Four novel variants were first reported herein, expanding the mutational spectra for HEK-related genes. Following counseling, 52 families chose to continue the pregnancy, and in 23 of them, postnatal ultrasound showed no detectable renal abnormalities. Of these 23 cases, 15 had isolated HEK on prenatal ultrasound. Taken together, our study showed a high rate of detectable genetic etiologies in cases with fetal HEK at the levels of chromosomal (aneuploidy), sub-chromosomal (microdeletions/microduplications), and single gene (point mutations). Therefore, we speculate that combined CMA and ES testing for fetal HEK is feasible and has good clinical utility. When no genetic abnormalities are identified, the findings can be transient, especially in the isolated HEK group.