Yi Wu

Fetal central nervous system (CNS) anomalies are among the most common congenital malformations, yet the overall prenatal diagnostic yield of current genetic testing remains below 40%. Variants in RNU4‐2 , a non‐coding gene encoding the U4 small nuclear RNA (snRNA), have recently been linked to a novel highly recurrent dominant neurodevelopmental disorder termed ReNU syndrome. While its postnatal phenotype has been well characterized, the contribution of RNU4‐2 to fetal CNS anomalies remains unexplored. In this study, we retrospectively analyzed 148 fetuses with CNS anomalies who had non‐diagnostic results from karyotyping, chromosomal microarray analysis, and exome sequencing. Targeted Sanger sequencing of RNU4‐2 was performed to identify pathogenic variants. Two fetuses harbored the same de novo recurrent variant, n.64_65insT, corresponding to a diagnostic yield of 1.35%. Both cases presented with microcephaly, suggesting that it is a key prenatal feature of ReNU syndrome. Furthermore, molecular confirmation of RNU4‐2 resolved a decade‐long diagnostic odyssey in one family by excluding an inherited Xp22.13 duplication of uncertain significance as the causal variant. In conclusion, this study provides the first systematic prenatal evaluation of RNU4‐2 in fetuses with CNS anomalies, thereby expanding the prenatal phenotypic spectrum of ReNU syndrome. Incorporating RNU4‐2 testing into prenatal genetic workflows may enhance diagnostic yield, enable precise genetic counseling, and support informed reproductive decision‐making.

Objective: To investigate the distribution of laterality defects in fetuses, including situs inversus totalis (SIT) and situs ambiguous (SA), and to explore the potential genetic etiology of these laterality defects.Methods: Detailed fetal echocardiography and extracardiac structural evaluations were performed. Genetic testing, including chromosomal microarray analysis, and trio exome sequencing was conducted to identify potential genetic variants.Results: The incidence of heart malformation was significantly higher in SA fetuses than in SIT group (30/31 vs. 2/36, p < 0.001). The incidence of univentricular heart with single atrium was significantly higher in right isomerism compared with left isomerism (12/19 vs. 3/12, p = 0.029), while the incidence of double outlet right ventricle was significantly higher in left isomerism (5/12 vs. 1/19, p = 0.022). Genetic testing identified variation within candidate genes of cardiac development. Except for CFAP300 c.604delG and KMT2D c.16351T>C, which were rated as “likely pathogenic”, all other variants were categorized as variants of uncertain significance, with some fetuses having compound heterozygous variations.Conclusion: Fetuses with SA have a significantly higher likelihood of concurrent heart malformations compared with those with SIT. Genetic testing identified potential genetic variants that may play crucial roles in the mechanisms underlying normal fetal visceral positioning. Further studies are needed to explore the clinical significance of these genetic variants and to improve our understanding of the etiology and management of fetal laterality defects.

Objective: This study aimed to investigate the genetic etiologies of fetuses with single atria and/or ventricle (SA or/and SV) using different genetic detection methods in a Chinese prenatal cohort. Methods: In this retrospective study, the various genetic results of 44 fetuses with SA and/or SV were analyzed. All 44 cases were tested by chromosomal microarray analysis (CMA) and karyotyping simultaneously, and 8 underwent whole exome sequencing (WES). Data on the pregnancy outcomes and neonatal prognoses were collected from medical records and postnatal follow-up. Results: The whole cohort of 44 fetuses included 14 SA cases (31.8%), 12 SV cases (27.3%), and 18 SA and SV cases (40.9%). A total of 9 pathogenic genetic results were detected by conventional karyotyping, CMA and trio-WES, indicating an overall detection rate of 20.5% (9/44). Six pathogenic chromosomal abnormalities were identified by CMA among the 44 cases, showing a detection rate of 13.6% (6/44). Two microdeletions being missed by karyotyping were diagnosed by CMA, showing an additional diagnostic yield of 4.5% for CMA in present cohort(2/44). Three pathogenic variants in two fetuses were identified by WES, indicating an incremental diagnostic yield of 4.5%(2/44) for WES in fetuses with SA or/and SV. Conclusion: In this study, WES achieved an additional diagnostic yield of 4.5% in fetuses with SA or/and SV. WES is valuable for fetal prognosis assessment and could add diagnostic value for fetuses with SA and/or SV when CMA is negative. It would be a valuable technique for the identification of underlying pathogenic variants in prenatal cohorts.

Background: Ventricular septal defect (VSD) is the most common subtype of congenital heart disease. In the present study, we aimed to determine whether chromosome aberration was associated with the occurrence of VSD and evaluate the association of VSD size, location and chromosome aberration with adverse outcomes in the Chinese fetuses. Methods: Fetuses with VSD and comprehensive follow-up data were included and evaluated retrospectively. Medical records were used to collect epidemiological data and foetal outcomes. For VSD fetuses, conventional karyotype and microarray analysis were conducted. After adjusting confounding factors by using multivariable logistic regression analyses, the association between chromosome variations and VSD occurrence was explored. The association between defect size, location and chromosome aberrations and adverse foetal outcomes was also investigated. Results: Chromosome aberration was the risk factor for VSD occurrence, raising 6.5-fold chance of developing VSD. Chromosome aberration, peri-membranous site and large defect size of VSD were significant risk factors of adverse fetal outcome. Chromosome aberrations, including pathogenic copy number variations (CNVs) and variations of uncertain significance (VUS), were both risk factors, increasing the risk of the adverse fetal outcome by 55.9 times and 6.7 times, respectively. The peri-membranous site would increase 5.3-fold risk and defects larger than 5 mm would increase the 7.1-fold risk for poor fetal outcome. Conclusions: The current investigation revealed that chromosomal abnormalities, large defects, and the peri-membranous site were all risk factors for poor fetal outcomes. Our study also indicated that chromosome aberration was one of risk factors for the VSD occurrence.

Ectrodactyly–ectodermal dysplasia–cleft (EEC) syndrome is an autosomal dominant disorder characterized by ectrodactyly, ectodermal dysplasia, and orofacial clefting. Reduced penetrance is manifested in these core features and additional under-recognized features, especially in prenatal cases. Here, we present a fetus with EEC syndrome at 22 weeks gestation, in which the cleft lip and palate and the right polycystic kidney are shown by prenatal ultrasound. A de novo missense mutation of R304W in the TP63 gene is confirmed by whole-exome sequencing associated with EEC syndrome. We further investigate the reported TP63-related prenatal cases and provide a more complete picture of the prenatal phenotypic spectrum about EEC. It illustrates the potential severity of genitourinary anomalies in TP63-related disorders and highlights the need to counsel for the possibility of EEC syndrome, given the occurrence of genitourinary anomalies with orofacial cleft or limb deformities.

Background: Congenital heart disease/defect (CHD) is one of the most common congenital disabilities. Early diagnosis of CHD can improve the prognosis of newborns with CHD. The aim of this study was to evaluate the relationship between the factors and the onset of fetal congenital heart disease by measuring fetal umbilical artery (UA) Doppler index, maternal HCY, and Cys C levels during pregnancy. Methods: This retrospective study analyzed 202 fetuses with CHD, including 77 cases (39.1%) of simple CHD and 120 cases (60.9%) of complex CHD. Singleton pregnant women who were examined at the same time and whose malformation screening did not suggest any structural abnormalities in the fetus were assigned to the control group (n = 400). The UA Doppler index, plasma HCY, and Cys C levels were compared among the pregnant women across the three groups, and logistic regression analysis was performed on statistically significant markers. The ROC of UA S/D, PI, RI, HCY, and Cys C were plotted, and the area under the ROC (AUC) was calculated. Results: The UA S/D, PI, and RI in the complex CHD group were significantly higher than those in the control group (p < 0.05). The levels of HCY and Cys C in the CHD group were significantly higher than those in the control group (p < 0.05). HCY and S/D revealed a positive correlation (r = 0.157), and the difference was statistically significant (p < 0.001). Cys C and S/D were positively correlated (r = 0.131), and the difference was statistically significant (p < 0.05). The levels of UA Doppler indices, maternal plasma HCY, and Cys C were elevated in fetuses with CHD. The AUC of the combined test of the UA index, HCY, and Cys C was higher than that of each individual test. Conclusions: Elevated levels of the UA doppler indices, HCY, and Cys C during pregnancy are positively associated with the development of congenital heart disease in offspring. The combination of HCY and Cys C was the most efficient test for the diagnosis of CHD. We are the first to report that plasma Cys C levels of women pregnant with fetuses with CHD were higher than those of women pregnant with normal fetuses.

Background: Chromosome 1p36 deletion syndrome is a contiguous genetic disorder with multiple congenital anomalies and mental retardation. It has been emerging as one of the most common terminal deletion syndromes in humans with the rapid utility of microarray analysis. However, the prenatal findings of 1p36 deletion syndrome are still limited. We report a fetus with 1p36 deletion and cardiac phenotype of dextrocardia, combined with a balanced translocation between chromosome 5 and 6. The phenotype of dextrocardia is rarely reported in prenatal 1p36 deletion cases. Case presentation: We present a prenatal 1p36 deletion case with congenital heart diseases and single umbilical artery. Fetal echocardiography showed dextrocardia, ventricular septal defect and pericardial effusion. Fetal karyotype revealed a de novo balanced translocation of 46,XY,t(5;6)(q11.2;q23.3). Chromosomal microarray analysis detected a pathogenic deletion in 1p36.21p36.12, with the size of 6.38 Mb. Further whole genome sequencing revealed that the balanced translocation disrupted the EYA4 and ITGA1 genes. Conclusions: Although congenital heart diseases are very common clinical manifestations among patients with 1p36 deletion, dextrocardia is a quite rare cardiac phenotype. This is the second case with 1p36 deletion and dextrocardia, and the first prenatally diagnosed 1p36 deletion case with dextrocardia. Our case indicates that genes in 1p36 are associated with not only heart structural anomalies, but also cardiac laterality development. Our results also imply that the EYA4 gene disrupted by the balanced translocation might be related with the cardiac development.

Recombinant chromosome 4 syndrome (rec 4 syndrome) is a rare genetic disorder, predominately resulting from a parental pericentric inversion of chromosome 4. To date, a total of 18 cases of rec (4) syndrome were published in literature. We report the first kindred of rec (4) syndrome analyzed using copy number variation sequencing (CNV-seq). A woman with two adverse fetal outcomes was described in the present study. The first fetus presented with severe intrauterine growth restriction, hyposarca, hydrothorax and ascites. The CNV-seq revealed a dup 4q and del 4p. The second fetus presented with cardiovascular disease of ventricular septal defect, overriding aorta and persistent trunk. The CNV-seq revealed a dup 4p and del 4q. We collected 18 rec (4) cases through literature review. Genotype-phenotype correlation analysis was also performed. Recombinant 4 syndrome is a rare genetic disorder. It should be divided into two categories according to the alternative recombinant types. The clinical manifestations of rec (4) cases with dup 4q and del 4p are consistent with the Wolf-Hirschhorn syndrome. For cases harboring dup 4p and del 4q, the high incidence of congenital heart disease is prominent.