Prenatal diagnosis of Wolf-Hirschhorn syndrome: from ultrasound findings, diagnostic technology to genetic counseling

Single nucleotide polymorphism array (SNP-array) analysis for fetuses with abnormal nasal bone

PURPOSE

This study aims to evaluate the prevalence of submicroscopic chromosomal abnormalities found on single nucleotide polymorphism array (SNP array) in pregnancies with either an absent or hypoplastic nasal bone.

METHODS

This retrospective study included 333 fetuses with either nasal bone hypoplasia or absence identified on prenatal ultrasound. SNP array analysis and conventional karyotyping were performed in all the subjects. The prevalence of chromosomal abnormalities was adjusted for maternal age and other ultrasound findings. Fetuses with either an isolated nasal bone absence or hypoplasia, those that had additional soft ultrasound markers, and those where structural defects were found on ultrasound were divided into three groups: A, B, and C, respectively.

RESULTS

Among the total cohort of 333 fetuses, 76 (22.8%) had chromosomal abnormalities, including 47 cases of trisomy 21, 4 cases of trisomy 18, 5 cases of sex chromosome aneuploidy, and 20 cases of copy number variations of which 12 were pathogenic or likely pathogenic. The prevalence of chromosomal abnormalities in group A (n = 164), B (n = 79), and C (n = 90) was 8.5%, 29.1% and 43.3%, respectively. The incremental yields by SNP-array compared with karyotyping in group A, B, and C were 3.0%, 2.5% and 10.7%, respectively (p > 0.05). Compared to karyotype analysis, SNP array detected an additional 2 (1.2%), 1 (1.3%), and 5 (5.6%) pathogenic or likely pathogenic CNVs in groups A, B, and C, respectively. In the 333 fetuses, the prevalence of chromosomal abnormalities in women with advanced maternal age (AMA) was significantly higher than that in non-AMA women, (47.8% vs. 16.5%, p < 0.05).

CONCLUSION

In addition to Down's syndrome, many other chromosomal abnormalities are present in fetuses with abnormal nasal bone. SNP array can improve the prevalence of chromosomal abnormalities associated with nasal bone abnormalities, especially in pregnancies with non-isolated nasal bone abnormalities and advanced maternal age.

Prenatal evaluation of genetic variants in fetuses with small head circumference: A single-center retrospective study

OBJECTIVES

To comprehensively evaluate the contributions of numerical chromosomal abnormality, copy number variant (CNV), and sequence variant (SV) to fetuses with small head circumference in a Chinese cohort using chromosome microarray analysis and whole exome sequencing.

METHODS

A total of 157 fetuses with small heads defined as head circumference < - 2 standard deviation (SD) were recruited between October 2014 and March 2023. We used the ultrasonic measurement parameter Z-score to define small head as possible microcephaly (3 < Z ≤ -2), microcephaly (-5 < Z ≤ -3), or pathologic microcephaly (Z ≤ -5). Ultrasound findings and genetic results were analyzed.

RESULTS

The overall diagnostic yield of chromosomal abnormalities by microarray analysis was 13 %. Whole exome sequencing revealed eight novel variants and two interesting candidate genes and provided a 25.4 % incremental yield compared with microarray analysis. Of the detected SVs, 56 % were de novo and the most common inheritance pattern was autosomal dominant inheritance presented in 11/16 fetuses. Compared with isolated small heads, non-isolated small heads had a significantly higher detection rate of chromosomal abnormalities (16 % vs. 3.0 %, P = 0.049) but not SVs (24 % vs. 5.5 %, P = 0.126). Subgroup analysis showed that intracranial anomalies had a similar high detection rate of SVs in fetuses with all small heads subgroups while no chromosomal abnormalities and causative SVs were found in fetuses with isolated possible microcephaly.

CONCLUSIONS

Ultrasound findings of small fetal head circumference < 3 SD below the mean, especially those with intracranial structural abnormalities, indicate the need for genetic counseling. Genetic variants, mainly copy number variants and SV, may be responsible for the substantial proportion of small fetal head circumference, while most are de novo. Whole exome sequencing and microarray analysis are effective diagnostic approaches for this population.

Residual risk of clinically significant copy number variations in fetuses with nasal bone absence or hypoplasia after excluding non-invasive prenatal screening-detectable findings

BACKGROUND

It remains controversial whether prenatal screening or diagnostic testing should be offered to fetuses with nasal bone (NB) absence or hypoplasia, and there are no studies comparing the yield of chromosomal microarray analysis (CMA) to non-invasive prenatal screening (NIPS). The aim of this study was to evaluate the residual risk of clinically significant copy number variations (CNVs) in fetuses with NB absence or hypoplasia after excluding theoretically NIPS-detectable abnormalities, and to assess their clinical outcomes.

METHODS

This prospective study encompassed 400 fetuses with NB absence or hypoplasia undergoing CMA testing between 2015 and 2022. Clinically significant CMA findings were categorized into three subgroups, including three-NIPS-detectable (trisomies 21, 18 and 13), five-NIPS-detectable (trisomies 21, 18 and 13 and sex chromosome aneuploidies) and genome-wide NIPS-detectable (variants over 7 Mb). We calculated the theoretical residual risk and compared it with the results of a control cohort of low-risk pregnancies. We further evaluated their clinical outcomes.

RESULTS

The overall diagnostic yield in our cohort was 7.8% (31/400). The detection rate of clinically significant CMA findings in fetuses with non-isolated NB absence or hypoplasia was significantly higher than that in fetuses with isolated NB absence or hypoplasia (20.0% vs. 6.6%, P =.005). The theoretical residual risks in all NIPS models were significantly higher when compared with the control cohort. The normal infant rate in fetuses with normal CMA results was 97.9% (323/330), and a significant higher incidence was observed in fetuses with isolated NB absence or hypoplasia compared with non-isolated NB absence or hypoplasia (98.4% vs. 91.7%, P =.028).

CONCLUSIONS

The residual risk of clinically significant CNVs in fetuses with NB absence or hypoplasia following the exclusion of theoretically NIPS-detectable findings was higher than that in low-risk pregnancies. This risk should be considered in genetic counseling to make a more comprehensive and precise choice regarding prenatal genetic testing.

Wolf-Hirschhorn Syndrome with Hyperparathyroidism: A Case Report and a Narrative Review of the Literature

Wolf-Hirschhorn syndrome (WHS) is a contiguous gene deletion condition. The WHS core phenotype includes developmental delays, intellectual disabilities, seizures, and distinctive facial features. Various other comorbidities have also been reported, such as hearing loss, heart defects, as well as eye problems and kidney problems. In this report, we present a case of WHS accompanied by hyperparathyroidism and hypercalcemia, which has not been previously reported. A girl was born at 37 weeks of gestation by vaginal delivery. She was small for the gestational age (2,045 g) and admitted to neonatal intensive care unit. She had typical WHS facial features and was found to have bilateral small kidneys associated with transient metabolic acidosis and renal insufficiency. She had right-sided sensorineural hearing loss, a small atrial septal defect, and colpocephaly and hypoplasia of corpus callosum. She had a single seizure which was well controlled with an oral antiepileptic medication. Cytogenetic studies demonstrated a large terminal chromosome 4p deletion (21.4 Mb) and 4p duplication (2.1 Mb) adjacent to the deletion. A unique finding in this patient is her consistently elevated levels of parathyroid hormone and serum calcium, suggesting hyperparathyroidism. We present this rare case along with a review of the literature and hope to draw an attention to a potential relationship between WHS and hyperparathyroidism.

Prenatal chromosomal microarray analysis in foetuses with isolated absent or hypoplastic nasal bone

OBJECTIVES

To evaluate the efficiency of chromosomal microarray analysis (CMA) in the prenatal diagnosis of foetuses with isolated absent or hypoplastic nasal bone (NB) in the first and second trimester.

METHODS

From January 2015 to April 2021, foetuses with isolated absent or hypoplastic NB who received invasive prenatal diagnosis were enrolled. The results of CMA were analysed.

RESULTS

There were 221 foetuses, including 166 cases with isolated absent NB and 55 cases with isolated hypoplastic NB. Twenty-four foetuses (10.9%, 24/221) had an ultrasonic diagnosis in the first trimester and 197 (89.1%, 197/221) had a ultrasonic diagnosis in the second trimester. The overall diagnostic yield of CMA was 9.0% (20/221). Aneuploidies were detected in 13 (5.9%, 13/221) foetuses, including 10 Down syndrome, 2 Klinefelter's syndrome and 1 trisomy 18. Pathogenic copy number variations (CNVs) were detected in seven foetuses (3.2%, 7/221). In addition, variants of unknown significance (VOUS) were detected in four foetuses. The foetuses with isolated absent NB had a higher detection rate of chromosome abnormality than the isolated hypoplastic NB, but the difference was not significant in the statistical analysis (10.2% vs. 5.5%, χ² =0.642, p = .423). No significant difference was observed in the detection rate between the first trimester and the second trimester (16.6% vs. 8.1%, χ² = 1.002, p = .317, Chi-square test).

CONCLUSION

CMA can increase the diagnostic yield of chromosome abnormality, especially pathogenic CNVs for foetuses with isolated absent or hypoplastic NB. CMA should be recommended when isolated absent or hypoplastic NB is suspected antenatally.7.

Role of Sonographic Second Trimester Soft Markers in the Era of Cell-Free DNA Screening Options: A Review

Soft markers are sonographic structural, nonspecific signs with little pathological significance, often transient, usually considered as normal variants. However, they may also be associated with chromosomal abnormalities. The most widely examined soft markers include absent or hypoplastic nasal bone (NB), intracardiac echogenic focus (IEF), ventriculomegaly (VM), thickened nuchal fold (NF), choroid plexus cyst (CPC), echogenic bowel, short long bones, and urinary tract dilation (UTD). Although the use of noninvasive prenatal testing (NIPT) has been spreading quickly in maternal–fetal medicine, it is not a diagnostic test and it still remains unavailable or cost-prohibitive for most of the population in many countries. After normal screening test results in the first trimester, there is no uniform consensus regarding the clinical significance of isolated soft markers for aneuploidy. Nowadays, the search for soft markers in an ultrasound is still part of clinical evaluation, and the interpretation of these findings is often a matter of debate. In the present review, we summarize the recent literature about the role of soft markers in the era of NIPT and propose an overview of the different clinical guidelines.

Prenatal sonographic findings in confirmed cases of Wolf-Hirschhorn syndrome

Background

Wolf-Hirschhorn syndrome (WHS) is a common genetic condition and prenatal diagnosis is difficult due to heterogeneous expression of this syndrome and rather non-specific ultrasound findings. Objective of this study was to examine the prenatal ultrasound findings in fetuses with Wolf-Hirschhorn syndrome (WHS).

Methods

Retrospective assessment of 18 pregnancies that were seen at three tertiary referral centers (Universities of Bonn, Tuebingen and Nuernberg / Germany). Findings of prenatal ultrasound examinations, genetic results and outcome were compared. Additionally, findings of our study were compared to previous small case series from the literature and then compared to data on postnatal frequencies and abnormalities in affected patients.

Results

Median gestational age at the time of examination was 23 + 1 weeks’ (range: 13 + 4 to 29 + 1 weeks’) with female-to-male ratio of > 2.5:1. Most frequent ultrasound findings were facial abnormalities, symmetric IUGR and microcephaly that presented in 94.4, 83.3 and 72.2% of cases, respectively. The combination of microcephaly and hypoplastic nasal bone was a particularly characteristic finding. Growth retardation presented in all fetuses > 20 weeks, but not below. Other frequent abnormalities included cardiac anomalies in 50 and single umbilical artery (SUA) in 44.4% of fetuses.

Conclusion

WHS should be considered in the presence of symmetric IUGR together with microcephaly, hypoplastic nasal bone and facial abnormalities on prenatal ultrasound. Genetic testing by chromosomal microarray analysis (CMA) is strongly recommended in this context.

Fetal growth restriction: associated genetic etiology and pregnancy outcomes in a tertiary referral center

Background

The etiology of fetal growth restriction (FGR) is complex and currently, there is a paucity of research about the genetic etiology of fetal growth restriction. We investigated the genetic associations and pregnancy outcomes in cases of fetal growth restriction.

Methods

A retrospective analysis of 210 pregnant women with fetal growth restriction was performed using karyotype analysis and single nucleotide polymorphism arrays (SNP-array). The differences in pathogenic copy number variation (CNV) detected by the two methods were compared. At the same time, the fetuses were divided into three groups: isolated FGR (n = 117), FGR with ultrasonographic soft markers (n = 48), and FGR with ultrasonographic structural anomalies (n = 45). Further, the differences in pathogenic copy number variations were compared among the groups.

Results

The total detection rate of pathogenic CNVs was 12.4% (26/210). Pathogenic copy number variation was detected in 14 cases (6.7%, 14/210) by karyotype analysis. Furthermore, 25 cases (11.9%, 25/210) with pathogenic CNVs were detected using the SNP-array evaluation method. The difference in the pathogenic CNV detection rate between the two methods was statistically significant. The result of the karyotype analysis and SNP-array evaluation was inconsistent for 13 cases with pathogenic CNV. The rate of detecting pathogenic CNVs in fetuses with isolated FGR, FGR combined with ultrasonographic soft markers, and FGR combined with ultrasonographic structural malformations was 6.0, 10.4, and 31.1%, respectively, with significant differences among the groups. During the follow-up, 35 pregnancies were terminated, two abortions occurred, and 13 cases were lost to follow-up. Of the 160 deliveries, nine fetuses had adverse pregnancy outcomes, and the remaining 151 had normal postnatal growth and developmental assessments.

Conclusions

Early diagnosis and timely genomic testing for fetal growth restriction can aid in its perinatal prognosis and subsequent intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03373-z.

Is Prenatal Diagnosis Necessary for Fetal Isolated Nasal Bone Absence or Hypoplasia?

Purpose

This study aimed to explore the value of chromosomal microarray analysis (CMA) and whole exome sequencing (WES) in the prenatal diagnosis of fetal isolated nasal bone absence (INBA) or isolated nasal bone hypoplasia (INBH). We hope to provide additional relevant information for clinical counseling.

Patients and Methods

From November 1, 2018, to March 1, 2020, 55 pregnant women with isolated nasal bone dysplasia were admitted to the Changzhou Maternity and Child Health Care Hospital. Based on the degree of abnormality, the patients were divided into two groups: INBA and INBH. CMA was performed on all patients. The clinical data and prenatal genetic diagnoses of the two groups were retrospectively analyzed. According to the requirements of WES for samples, 12 cases with negative CMA results were selected for the WES test.

Results

A total of 55 cases with INBA or INBH met the inclusion criteria. In 35INBA fetuses, there was one case of trisomy 21 and one case of 10q11.22 deletion (5.7Mb), and the abnormality rate was 5.71% (2/35). Compared with INBA fetuses, the abnormality rate was increased in the fetuses with INBH [15.00% (3/20)] (15.00% vs 5.71%); there was one case of 1q21.1 duplication (1.3Mb), one case of Xp22.31 duplication (1.67Mb), and one case of 4p deletion (7.6Mb). In a later retrospective study, two pathogenic variants were identified in two cases after the WES test; the abnormality rate was 16.67% (2/12), which involved RUNX2 and CDH4 genes, respectively.

Conclusion

A preliminary study confirmed that molecular prenatal diagnosis should be performed in fetuses with INBA or INBH. CMA followed by WES is an effective method.

Investigation on combined copy number variation sequencing and cytogenetic karyotyping for prenatal diagnosis

Background

We aimed to evaluate the clinical value of copy number variation-sequencing (CNV-Seq) in combination with cytogenetic karyotyping in prenatal diagnosis.

Methods

CNV-Seq and cytogenetic karyotyping were performed in parallel for 9452 prenatal samples for comparison of the diagnostic performance of the two methods, and to evaluate the screening performance of maternal age, maternal serum screening, fetal ultrasound scanning and noninvasive prenatal testing (NIPT) for fetal pathogenic copy number variation (CNV).

Results

Among the 9452 prenatal samples, traditional karyotyping detected 704 cases (7.5%) of abnormal cytogenetic karyotypes, 171 (1.8%) chromosome polymorphism, 20 (0.2%) subtle structural variations, 74 (0.7%) mutual translocation (possibly balanced), 52 (0.6%) without karyotyping results, and 8431 (89.2%) normal cytogenetic karyotypes. Among the 8705 cases with normal karyotype, polymorphism, mutual translocation, or marker chromosome, CNV-Seq detected 63 cases (0.7%) of pathogenic chromosome microdeletion/duplication. Retrospectively, noninvasive prenatal testing (NIPT) had high sensitivity and specificity for the screening of fetal pathogenic CNV, and NIPT combining with maternal age, maternal serum screening or fetal ultrasound scanning, which improved the screening performance.

Conclusion

The combined application of cytogenetic karyotyping and CNV-Seq significantly improved the detection rate of fetal pathogenic chromosome microdeletion/duplication. NIPT was recommended for the screening of pathogenic chromosome microdeletion/duplication, and NIPT combining with other screening methods further improved the screening performance for pathogenic fetal CNV.

Wolf-Hirschhorn syndrome: Prenatal diagnosis and molecular cytogenetic characterization of a de novo distal deletion of 4p (4p16.1 → pter) in a fetus with facial cleft and preaxial polydactyly

OBJECTIVE

We present prenatal diagnosis and molecular cytogenetic characterization of Wolf-Hirschhorn syndrome (WHS) in a fetus with facial cleft and preaxial polydactyly.

MATERIALS AND METHODS

A 37-year-old woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age, and the result showed an aberrant chromosome 4 or 46,XX,add(4) (p15.3). The woman consulted our clinics at 22 weeks of gestation and requested for repeat amniocentesis. Prenatal ultrasound revealed intrauterine growth restriction, facial cleft, vermian hypoplasia of cerebellum, micrognathia and absent stomach. Conventional cytogenetic analysis was performed on cultured amniocytes, parental bloods and cord blood. Array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on the DNAs extracted from uncultured amniocytes and parental bloods. Fluorescence in situ hybridization (FISH) analysis was performed on cultured metaphase amniocytes.

RESULTS

aCGH analysis on uncultured amniocytes revealed arr 4p16.3p16.1 (74,447-8,732,731) × 1.0 [GRCh37 (hg19)] with an 8.66-Mb deletion of 4p16.3-p16.1 encompassing 70 [Online Mendelian Inheritance of in Man (OMIM)] genes including ZNF141, FGFRL1, TACC3, LETM1, NSD2 and NELFA. QF-PCR revealed a paternal origin of the distal 4p deletion. Conventional cytogenetic analysis revealed 46,XX,del(4) (p16.1)dn in the fetus. Metaphase FISH analysis confirmed a 4p16 deletion. The parental karyotypes were normal. The pregnancy was subsequently terminated, and a malformed fetus was delivered with typical WHS facial dysmorphism, bilateral cleft lip and palate, and preaxial polydactyly on the right hand.

CONCLUSION

aCGH, QF-PCR and FISH help to delineate the nature of a prenatally defected aberrant chromosome, and the acquired information is useful for genetic counseling.

Nonossified cervical vertebrae in Wolf-Hirschhorn Syndrome: A case report

RATIONALE

Wolf-Hirschhorn Syndrome (WHS) is a rare disorder caused by the loss of the distal part of the short arm of chromosome 4, and has various phenotypes depending on the deletion size. Although many articles report on urinary tract malformations or ophthalmologic abnormalities, there are few descriptions of the skeletal anomalies. This is an extremely rare case of cervical dysplasia in WHS.

PATIENT CONCERNS

A 24-year-old pregnant woman was transferred to our hospital at 21 gestational weeks for intrauterine growth retardation and oligohydramnios and decided to preserve the pregnancy after evaluation. A female was born at full term by normal vaginal delivery, weighing 1791 g. The patient was suspected to have congenital dysplasia of the cervical vertebrae on the routine newborn chest radiograph, and cervical spine magnetic resonance imaging revealed nonossification of the C3 and C4 vertebral bodies.

DIAGNOSIS

The newborn had the "Greek warrior helmet" face typical of WHS. A deletion was detected in the distal portion of the short arm of chromosome 4 (p 16.3) by fluorescence in situ hybridization analysis.

INTERVENTIONS

She was hospitalized for nutritional management and congenital anomaly evaluation for a month before being discharged with rehabilitation and antiepileptic drugs.

OUTCOMES

The patient has been readmitted with seizure attacks 5 times to date. At one year of age, she still shows severe head lag and feeding problems. Her last weight was below the 3rd centile.

LESSONS

Although cervical dysplasia is a rarely reported morphology in WHS, it may provide artefacts for diagnosing WHS as cervical anomalies, unlike facial anomalies or developmental delays, are seldom found in congenital disease.

Hypoplastic nasal bone: A potential marker for facial dysmorphism associated with pathogenic copy number variants on microarray

OBJECTIVES

To compare the frequency of abnormal genetic diagnoses spanning a period before and after the availability of chromosomal microarray analysis (CMA). We hypothesised that microarray would provide additional clinically relevant information in cases of isolated hypoplastic nasal bone.

METHOD

Fetuses with ultrasound-detected hypoplastic nasal bone (absent or <2.5th percentile in length) between 16 and 37 weeks' gestation over a 10-year period were analysed retrospectively.

RESULTS

A total of 118 cases of hypoplastic nasal bone met the inclusion criteria. A pathogenic or potentially pathogenic karyotype was detected more frequently in the era where CMA was available (31/60, 52% vs 19/58, 33%). Of these, 25 cases (42%) had common aneuploidies, and six cases (10%) had clinically relevant copy number variants (CNVs). A clinically relevant CNV was detected in two fetuses that presented with isolated hypoplastic nasal bone on initial ultrasound.

CONCLUSION

In addition to its known association with trisomy 21, a hypoplastic nasal bone may be an objective marker of facial dysmorphism associated with clinically relevant CNVs. Our results support consideration of invasive testing with microarray for pregnancies in which a hypoplastic nasal bone has been diagnosed on ultrasound irrespective of a low-risk screening result for common chromosomal abnormalities.