Prenatal diagnosis of Simpson-Golabi-Behmel syndrome

Simpson-Golabi-Behmel syndrome

The Simpson-Golabi-Behmel syndrome (SGBS; OMIM 312870) is an overgrowth/multiple congenital anomalies/dysplasia condition, inherited as an X-linked semi-dominant trait, with variable expressivity in males and reduced penetrance and expressivity in females. The clinical spectrum is broad, ranging from mild manifestations in both males and females to multiple malformations and neonatal death in the more severely affected cases. An increased risk of neoplasia is reported, requiring periodical surveillance. Intellectual development is normal in most cases. SGBS is caused by a loss-of-function mutation of the GPC3 gene, either deletions or point mutations, distributed all over the gene. Notably, GPC3 deletion/point mutations are not found in a significant proportion of clinically diagnosed SGBS cases. The protein product GPC3 is a glypican functioning as a receptor for Hh at the cell surface, involved in the Hh-Ptc-Smo signaling pathway, a regulator of cellular growth.

Prenatal diagnosis of Simpson-Golabi-Behmel syndrome type 1 with an 814 kb Xq26.2 deletion with the initial presentation of a thick nuchal fold

OBJECTIVE

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is a rare X-linked recessive disorder characterized by overgrowth and multiple anomalies. Most clinical diagnoses of SGBS1 are made postnatally. We present the case of a pregnant woman in whom the fetus presented with a thick nuchal fold 5.6 mm at 15 weeks of gestation, leading to the prenatal diagnosis of SGBS1 with Xq26.2 (133408101-134221889) deletion.

CASE REPORT

We report the case of a 34-year-old pregnant woman with the initial presentation of fetal thick nuchal fold 5.6 mm at 15 weeks of gestation. Amniocentesis of the fetal karyotype revealed a normal 46, XY, and single nucleotide polymorphism array showed Xq26.2 (133408101-134221889) deletion. Prenatal ultrasound at 21 weeks of gestation revealed a thick nuchal fold, hepatomegaly, nephromegaly, congenital diaphragmatic hernia, hypospadias, and polyhydramnios. Fetal magnetic resonance imaging revealed hepatomegaly, nephromegaly, congenital diaphragmatic hernia, and right lung hypoplasia. The woman had her pregnancy terminated at 24 weeks of gestation. The proband had a general appearance of low-set ears, hypertelorism, a large tongue, and hypospadias and some unique findings on autopsy, including hepatomegaly, right hiatal hernia, liver extensive extramedullary hematopoiesis, kidney marked congestion, and focal hemorrhage.

DISCUSSION

The main prenatal ultrasound findings that alert clinical doctors about the possible diagnosis of SGBS1 included macrosomia, polyhydramnios, organomegaly, renal malformations, congenital diaphragmatic hernia, and cardiac anomalies. Our case underscores the importance of fetal karyotyping combined with single nucleotide polymorphism array when a thick nuchal fold is found. Genetic counseling is essential in SGBS1, and prenatal testing or preimplantation testing for subsequent pregnancies is necessary to identify possible pathogenic variants.

Simpson-Golabi-Behmel syndrome in one of the Dichorionic-diamniotic twin: a case report and literature review

Background

Simpson-Golabi-Behmel syndrome (SGBS) is a rare X-linked overgrowth syndrome. The main clinical manifestations are overgrowth and multiple malformations.

Case presentation

A 38-year-old Chinese woman was pregnant with dichorionic-diamniotic (DCDA) twins after in-vitro fertilization. Series of ultrasound examinations indicated that the measurements (abdominal circumference and estimated foetal weight) of one twin were significantly greater than those of the other one. The genetic testing results of the larger baby indicated of Simpson-Golabi-Behmel syndrome.

Conclusion

SGBS is difficult to diagnose due to different clinical manifestations. Clinicians need to be more aware of typical SGBS’s clinical findings and choose genetic testing methods individually to improve its prenatal diagnosis.

Prenatal case of Simpson-Golabi-Behmel syndrome with a de novo 370Kb-sized microdeletion of Xq26.2 compassing partial GPC3 gene and review

BACKGROUND

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is a rare X-linked recessive disorder characterized by pre- and postnatal overgrowth and a broad spectrum of anomalies including craniofacial dysmorphism, heart defects, renal, and genital anomalies. Due to the ultrasound findings are not pathognomonic for this syndrome, most clinical diagnosis of SGBS1 are made postnatally.

METHODS

A pregnant woman with abnormal prenatal sonographic findings was advised to perform molecular diagnosis. Single nucleotide polymorphism array (SNP array) was performed in the fetus, and the result was validated with multiplex ligation-dependent probe amplification (MLPA) and real-time quantitative PCR (qPCR).

RESULTS

The prenatal sonographic presented with increased nuchal translucency at 13 gestational weeks, and later at 21 weeks with cleft lip and palate, heart defect, increased amniotic fluid index and over growth. A de novo 370Kb-deletion covering the 5'-UTR and exon 1 of GPC3 gene was detected in the fetus by SNP array, which was subsequently confirmed by MLPA and qPCR.

CONCLUSION

The de novo 370Kb hemizygous deletion of 5'-UTR and exon 1 of GPC3 results in the SGBS1 of this Chinese family. Combination of ultrasound and genetics tests helped us effectively to diagnose the prenatal cases of SGBS1. Our findings also enlarge the spectrum of mutations in GPC3 gene.

Application of next-generation sequencing for the diagnosis of fetuses with congenital heart defects

PURPOSE OF REVIEW

Congenital heart defects (CHDs) are the most common type of birth defects, and are thought to result from genetic-environmental interactions. Currently, karyotype and chromosomal microarray analyses are the primary methods used to detect chromosomal abnormalities and copy number variations in fetuses with CHD. Recently, with the introduction of next-generation sequencing (NGS) in prenatal diagnosis, gene mutations have been identified in cases of CHD. The purpose of this review is to summarize current studies about the genetic cause of fetal CHD, paying particular attention to the application of NGS for fetuses with CHD.

RECENT FINDINGS

In addition to chromosomal abnormalities, gene mutations are an important genetic cause of fetal CHD. Furthermore, incidences of pathogenic mutations in fetuses with CHD are associated with the presence of other structural anomalies, but are irrelevant to the categories of CHD.

SUMMARY

Gene mutations are important causes of fetal CHD and NGS should be applied to all fetuses with normal karyotype and copy number variations, regardless of whether the CHD is isolated or syndromic.

Whole exome sequencing aids the diagnosis of Simpson-Golabi-Behmel syndrome in two male fetuses

Objective

To diagnose and explore the genetic aetiology of Simpson–Golabi–Behmel syndrome type 1 (SGBS1) in two male fetuses.

Methods

Prenatal ultrasound scans and further genetic analysis using karyotype analysis, chromosomal microarray analysis, whole exome sequencing (WES) and Sanger sequencing were conducted.

Results

Prenatal ultrasound scans of two fetuses showed multiple congenital anomalies and hydramnios. Subsequent to termination of the pregnancies, a novel nonsense variant (c.892G>T, p.E298*) in the glypican 3 (GPC3) gene of the two fetuses was identified by WES and further confirmed by Sanger sequencing. The two fetuses were diagnosed with SGBS1. The mother was heterozygous for the c.892G>T variant.

Conclusion

This study describes the prenatal sonographic features of SGBS1, emphasizes the role of WES in the diagnosis of SGBS1 and expands the known mutation spectrum of the GPC3 gene.

Two Consecutive Pregnancies with Simpson-Golabi-Behmel Syndrome Type 1: Case Report and Review of Published Prenatal Cases

Fetal overgrowth and numerous congenital malformations can be detected in every trimester of pregnancy. New technologies in molecular testing, such as chromosomal microarray analysis and next-generation sequencing, continually demonstrate advantages for definitive diagnosis in fetal life. Simpson-Golabi-Behmel (SGB) syndrome is a rare but well-known overgrowth condition that is rarely diagnosed in the prenatal setting. We report 3 cases of SGB syndrome in 2 consecutive pregnancies. In our series, distinctive prenatal sonographic findings led to molecular diagnosis. Exome sequencing from fetal DNA revealed a hemizygous splice site variant in the GPC3 gene: NM_004484.3:c.1166+ 1G>T. The mother is a heterozygous carrier. We also provide an overview of the previously published 57 prenatal cases of SGB syndrome with prevalence estimation of the symptoms to aid prenatal differential diagnosis of fetal overgrowth syndromes.

Mutation update for the GPC3 gene involved in Simpson-Golabi-Behmel syndrome and review of the literature

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked multiple congenital anomalies and overgrowth syndrome caused by a defect in the glypican-3 gene (GPC3). Until now, GPC3 mutations have been reported in isolated cases or small series and the global genotypic spectrum of these mutations has never been delineated. In this study, we review the 57 previously described GPC3 mutations and significantly expand this mutational spectrum with the description of 29 novel mutations. Compiling our data and those of the literature, we provide an overview of 86 distinct GPC3 mutations identified in 120 unrelated families, ranging from single nucleotide variations to complex genomic rearrangements and dispersed throughout the entire coding region of GPC3. The vast majority of them are deletions or truncating mutations (frameshift, nonsense mutations) predicted to result in a loss-of-function. Missense mutations are rare and the two which were functionally characterized, impaired GPC3 function by preventing GPC3 cleavage and cell surface addressing respectively. This report by describing for the first time the wide mutational spectrum of GPC3 could help clinicians and geneticists in interpreting GPC3 variants identified incidentally by high-throughput sequencing technologies and also reinforces the need for functional validation of non-truncating mutations (missense, in frame mutations, duplications).

Nonisolated diaphragmatic hernia in Simpson-Golabi-Behmel syndrome

OBJECTIVE

Congenital diaphragmatic hernia (CDH) is associated with Simpson-Golabi-Behmel syndrome (SGBS), but few cases diagnosed prenatally have been reported. The aim of this series is to highlight the association of nonisolated CDH with SGBS type I on prenatal ultrasound and emphasize the importance of genetic testing, fetal autopsy, and family history in confirming this diagnosis.

METHOD

Retrospective review of 3 cases of SGBS type I in a single tertiary care centre. Family history, fetal ultrasound, autopsy findings, and genetic testing for GPC3 was performed for each case.

RESULTS

Fetal ultrasound findings in the second trimester were CDH, omphalocele, increased nuchal fold, renal anomaly, and cleft lip and palate. Fetal autopsy confirmed the prenatal ultrasound findings and also showed dysmorphic facial features and premalignant lesions on renal and gonadal histology. Microarray and DNA analysis of the GPC3 gene confirmed the diagnosis of SGBS type I in each case.

CONCLUSION

Nonisolated CDH in a male fetus suggests a diagnosis of SGBS type I. Fetal autopsy, pedigree analysis, and genetic testing for GPC3 are all essential to confirming the diagnosis. The histological findings of ovotestes and nephroblastomatosis indicate that cancer predisposition is established early in fetal life.

Perinatal Case of Fatal Simpson-Golabi-Behmel Syndrome with Hyperplasia of Seminiferous Tubules

Patient: Male, newborn

Final Diagnosis: Simpson-Golabi-Behmel syndrome

Symptoms: Dyspnea

Medication: —

Clinical Procedure: —

Specialty: Pediatrics and Neonatology

First reported case of Simpson-Golabi-Behmel syndrome in a female fetus diagnosed prenatally with chromosomal microarray

Simpson–Golabi–Behmel syndrome (SGBS) is a rare X‐linked syndrome. Female carriers may have mild manifestations. Macrosomia, polyhydramnios, and kidney and urinary tract anomalies are common findings in male fetuses. We present the first case of a severely affected female fetus with stigmata of SGBS and a deletion involving the GPC3 gene.