The Genetic and Clinical Outcomes in Fetuses With Isolated Fetal Growth Restriction: A Chinese Single-Center Retrospective Study

Utility of whole exome sequencing in the evaluation of isolated fetal growth restriction in normal chromosomal microarray analysis

OBJECTIVE

To investigate the application of whole exome sequencing (WES) in the prenatal diagnosis of isolated fetal growth restriction (FGR) with a normal result by chromosomal microarray analysis (CMA).

METHODS

This retrospective study included singleton fetuses with isolated FGR in Guangdong Women and Children Hospital between July 2018 and August 2023. All fetuses were subjected to invasive prenatal testing with CMA and WES. Only cases with negative CMA results were included.

RESULTS

r  A total of 135 fetuses were included. Ultrasonography identified short long bones in 39 fetuses and nonshort long bones in 96 cases. WES revealed pathogenic/likely pathogenic (P/LP) variants in 16(11.9%) fetuses and variants of uncertain significance (VUS) in 2 (1.5%) fetuses. Compared to the nonshort long bones group, the short long bones group had a significantly higher detection rate of P/LP variants (33.3% [13/39] vs. 3.1% [3/96], p < 0.001, OR=15.5(4.1-58.5)). No significant differences were observed in the detection rates between severe FGR and nonsevere FGR (12.3% [13/106] vs. 10.3% [3/29], p= .000, OR=1.2(0.3-4.6)), or between the early-onset (12.9% [15/116]) and the late-onset group (5.3%[1/19],p =0.565, OR=2.7(0.3-21.5)).

CONCLUSIONS

P/LP variants are more prevalent in fetuses with short long bones. WES is recommended for isolated FGR with short long bones, but further studies are needed to assess its utility in cases with nonshort long bones.

Diagnostic yield of chromosomal microarray to examine the genetic factors associated with fetal aberrant right subclavian artery

PURPOSE

The primary objective was to find the risk factors that increase the probability of chromosomal abnormalities in fetal aberrant right subclavian artery (ARSA). Secondary objectives were to assess the factors which impact the adverse pregnancy outcomes in ARSA fetuses.

METHODS

This retrospective study included a total of 104 pregnant women whose fetuses were diagnosed with ARSA from January 2020 to July 2024, with subsequent chromosomal microarray analysis (CMA) performed.

RESULTS

Among the 104 cases of ARSA in this study, 46 (44.2%) were classified as isolated ARSA and 58 (55.8%) as non-isolated ARSA. Classification of non-isolated ARSA based on ultrasound soft marker abnormalities and structural abnormalities showed that an increase in the number of combined ultrasound soft marker abnormalities was associated with increased fetal chromosomal abnormalities and pathogenicity. In fetuses with structural abnormalities and ultrasonographic soft markers, they have more microarray abnormalities and higher pathogenicity compared to ARSA with only a single soft marker. The chromosomal abnormalities in ARSA fetuses predominantly manifest as trisomy 21, partial segmental microduplications, and microdeletions. Logistic regression analysis indicated that the presence of ultrasonographic soft marker abnormalities alongside ARSA serves as a risk factor for adverse pregnancy outcomes in ARSA fetuses.

CONCLUSION

In contrast to isolated ARSA, chromosomal disorders indicate a significant risk in ARSA accompanied by ultrasound abnormalities, and the risk is closely related to the number of ultrasonographic soft marker abnormalities. In addition, the combination of ultrasonographic soft marker abnormalities was a risk factor for adverse pregnancy outcomes in ARSA, while maternal age, structural abnormalities, polyhydramnios, and intrauterine growth restriction were not associated with it.

Advancing fetal diagnosis and prognostication using comprehensive prenatal phenotyping and genetic testing

Prenatal diagnoses of congenital malformations have increased significantly in recent years with use of high-resolution prenatal imaging. Despite more precise radiological diagnoses, discussions with expectant parents remain challenging because congenital malformations are associated with a wide spectrum of outcomes. Comprehensive prenatal genetic testing has become an essential tool that improves the accuracy of prognostication. Testing strategies include chromosomal microarray, exome sequencing, and genome sequencing. The diagnostic yield varies depending on the specific malformations, severity of the abnormalities, and multi-organ involvement. The utility of prenatal genetic diagnosis includes increased diagnostic clarity for clinicians and families, informed pregnancy decision-making, neonatal care planning, and reproductive planning. Turnaround time for results of comprehensive genetic testing remains a barrier, especially for parents that are decision-making, although this has improved over time. Uncertainty inherent to many genetic testing results is a challenge. Appropriate genetic counseling is essential for parents to understand the diagnosis and prognosis and to make informed decisions. Recent research has investigated the yield of exome or genome sequencing in structurally normal fetuses, both with non-invasive screening methods and invasive diagnostic testing; the prenatal diagnostic community must evaluate and analyze the significant ethical considerations associated with this practice prior to generalizing its use. IMPACT: Reviews available genetic testing options during the prenatal period in detail. Discusses the impact of prenatal genetic testing on care using case-based examples. Consolidates the current literature on the yield of genetic testing for prenatal diagnosis of congenital malformations.

The assessing of clinical relevance of chromosomal microarray analysis in the prenatal diagnosis of fetal growth restriction

OBJECTIVE

Chromosomal variations are known to play a role in the etiology of fetal growth restriction (FGR). Here, we intend to investigate the significance of Chromosomal Microarray Analysis (CMA) in the prenatal diagnosis of definite FGR.

METHOD

182 pregnant women with FGR participated in our study, undergoing CMA to identify chromosomal abnormalities. The cohort was categorized into isolated FGR, FGR with ultrasound soft marker abnormalities, and FGR associated with structural malformations.

RESULTS

The detection rates of PCNVs in FGR with structural anomalies are significantly higher than those in the isolated FGR group and the FGR group with abnormal ultrasound soft markers (19.0% vs. 2.1%, 19% vs. 1.5%; χ²=9.33, p = 0.005). Compared to FGR with a single system malformation, the diagnostic rate of chromosomal variations in FGR with multiple system malformations is markedly increased (60% vs. 6.3%; p = 0.028). Advanced maternal age, early-onset FGR, and severe FGR do not appear to influence the diagnostic rate of chromosomal variations (p > 0.05).

CONCLUSION

Chromosomal variations pose a significant risk in FGR with structural abnormalities, associated with the number of organ systems involved. Notably, advanced maternal age, early-onset FGR, and severe FGR do not affect the diagnostic rate of chromosomal variations in FGR.

Chromosomal Microarray Analysis in Fetuses with Ultrasound Abnormalities

Objective

To explore and evaluate the value of chromosomal microarray analysis (CMA) in prenatal diagnosis of fetuses with ultrasound abnormalities.

Methods

A retrospective analysis was performed on 370 fetuses with ultrasound abnormalities received invasive prenatal diagnosis at Meizhou People's Hospital from October 2022 to December 2023. Fetal specimens were analyzed by CMA, and the detection rates of aneuploidy and pathogenic (P)/likely pathogenic (LP) copy number variations (CNVs) in ultrasound structural abnormalities (malformations of fetal anatomy) and non-structural abnormalities (abnormalities of fetal nonanatomical structure) were analyzed.

Results

There were 114 (30.8%) cases with isolated ultrasound structural abnormalities, 226 (61.1%) cases with isolated non-structural abnormalities (182 isolated ultrasound soft markers abnormalities, 30 isolated fetal growth restriction (FGR), and 8 isolated abnormalities of amniotic fluid volume), and 30 (8.1%) cases with both structural and non-structural abnormalities. The overall detection rate of aneuploidy and P/LP CNVs in isolated ultrasonic structural abnormalities was 5.3%, among which cardiovascular system abnormalities were the highest. In addition, the largest number of fetuses with non-structural abnormalities was nuchal translucency (NT) thickening (n = 81), followed by ventriculomegaly (n = 29), and nasal bone dysplasia (n = 24). The detection rate of chromosomal abnormalities of fetuses with abnormal ultrasound soft markers was 9.9%, and the detection rate in single abnormal ultrasound soft marker, and multiple ultrasound soft markers abnormalities was 9.7% (16/165) and 11.8% (2/17), respectively. Moreover, the detection rate of chromosomal abnormalities of fetuses with FGR and structural abnormalities combined with non-structural abnormalities was 6.7% (2/30), and 13.3% (4/30), respectively.

Conclusion

The incidence of chromosomal abnormalities (aneuploidy and P/LP CNVs) varies among different fetal ultrasound abnormalities.

Genetic diagnosis of fetal microcephaly at a single tertiary center in China

Background: Microcephaly is common in patients with neuropsychiatric problems, and it is usually closely related to genetic causes. However, studies on chromosomal abnormalities and single-gene disorders associated with fetal microcephaly are limited. Objective: We investigated the cytogenetic and monogenic risks of fetal microcephaly and evaluated their pregnancy outcomes. Methods: We performed a clinical evaluation, high-resolution chromosomal microarray analysis (CMA), and trio exome sequencing (ES) on 224 fetuses with prenatal microcephaly and closely followed the pregnancy outcome and prognosis. Results: Among 224 cases of prenatal fetal microcephaly, the diagnosis rate was 3.74% (7/187) for CMA and 19.14% (31/162) for trio-ES. Exome sequencing identified 31 pathogenic or likely pathogenic (P/LP) single nucleotide variants (SNVs) in 25 genes associated with fetal structural abnormalities in 37 microcephaly fetuses; 19 (61.29%) of which occurred de novo. Variants of unknown significance (VUS) was found in 33/162 (20.3%) fetuses. The gene variant involved included the single gene MPCH 2 and MPCH 11, which is associated with human microcephaly, and HDAC8, TUBGCP6, NIPBL, FANCI, PDHA1, UBE3A, CASK, TUBB2A, PEX1, PPFIBP1, KNL1, SLC26A4, SKIV2L, COL1A2, EBP, ANKRD11, MYO18B, OSGEP, ZEB2, TRIO, CLCN5, CASK, and LAGE3. The live birth rate of fetal microcephaly in the syndromic microcephaly group was significantly higher than that in the primary microcephaly group [62.9% (117/186) vs 31.56% (12/38), p = 0.000]. Conclusion: We conducted a prenatal study by conducting CMA and ES for the genetic analysis of fetal microcephaly cases. CMA and ES had a high diagnostic rate for the genetic causes of fetal microcephaly cases. In this study, we also identified 14 novel variants, which expanded the disease spectrum of microcephaly-related genes.

Prenatal Diagnosis and Outcomes in Fetuses with Hemivertebra

Background: There are few studies on the burden of chromosomal abnormalities and single gene disorders in fetal hemivertebra (HV). We aim to investigate the cytogenetic and monogenic risk and evaluate prenatal outcomes of fetal HV. Method: This study included fetuses diagnosed with HV divided into two groups: isolated HV and non-isolated HV. Data on other sonographic structural anomalies, chromosomal and sub-chromosomal abnormalities, monogenic variations detected by WES, and prenatal outcomes are recorded and reviewed. Results: Among 109 fetal HV cases, forty-seven (43.1%) non-isolated HV cases were associated with structural anomalies. Chromosomal test results were available in 58 cases, identifying six (10.3%) chromosomal aberrations involved in four isolated and two non-isolated HV. WES identified four (likely) pathogenic variants in three cases among 16 fetuses with HV, involving three novel variants, 1250G > T and c.1277G> inherited from parents, respectively, in DLL3 and c.7213C > A ** in the FLNB. The live birth rate (LB) was higher in the isolated fetal HV group than in the non-isolated group (67.7% (42/62) vs. 12.5% (12/47), p < 0.001). Conclusion: This study emphasizes the risk of cytogenetic abnormalities in isolated HV. WES yields a diagnostic rate of 18.3% in HV with normal CMA, probably aiding the prenatal counseling and management of fetal HV.