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

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.

Simpson-Golabi-Behmel syndrome type 1 with normal birth parameters

A newborn baby born at 34 weeks and 5 days gestation was admitted for prematurity, dysmorphic features and congenital heart defects. Antenatal scan at 21 weeks showed a large-for-gestational-age foetus with a large abdominal circumference and liver, ventricular septal defect, right prominent renal pelvis and echogenic bowel. Antenatal genetic tests for overgrowth syndromes were negative. The mother had early onset pre-eclampsia. After birth, an overgrowth syndrome was still suspected despite the baby having normal birth parameters. Raw data of the trio whole exome sequencing from the amniocentesis sample were manually inspected. Hemizygous exon 7 deletion in the GPC3 gene was found, and a postnatal diagnosis of Simpson-Golabi-Behmel syndrome, a rare overgrowth syndrome, was made. This case report discusses the significance of antenatal findings, an atypical presentation of a rare syndrome and the obstacles of diagnostic genetic testing.

Prenatal ultrasound in fetuses with polycystic kidney appearance - expanding the diagnostic algorithm

PURPOSE

Report on the diagnosis of prenatally detected fetal kidneys with bilateral polycystic appearance in a single center between 1999 and 2020 with special focus on renal morphology and biometry, amniotic fluid and extrarenal findings and proposal for an diagnostic algorithm.

METHODS

Retrospective observational study including pregnancies with prenatally detected kidneys with bilateral polycystic appearance (n = 98). Cases and outcomes were compared according to prenatal findings with special focus on renal morphology, amount of amniotic fluid, and presence of extrarenal abnormalities.

RESULTS

Most frequent diagnoses were autosomal recessive polycystic kidney disease (ARPKD, 53.1%), Meckel-Gruber syndrome (MKS, 17.3%) and autosomal dominant polycystic kidney disease (ADPKD, 8.2%). Other diagnoses included: Joubert-, Jeune-, McKusick-Kaufman- and Bardet-Biedl syndrome, overgrowth syndromes, Mainzer-Saldino syndrome and renal tubular dysgenesis. Renal abnormalities most frequently observed were hyperechogenic parenchyma, kidney enlargement, changes of corticomedullary differentiation and cystic changes of various degree. Oligo- and anhydramnios were mainly seen in ARPKD, RTD and second-trimester MKS. Extrarenal findings included skeletal (35.7%) and cardiac (34.7%) abnormalities as well as abnormalities of the central nervous system (27.6%).

CONCLUSION

Gestational age at manifestation, kidney size, visibility of cysts, echogenicity, amniotic fluid volume, and the presence of associated extrarenal malformations allow to differentiate between the most frequent underlying diseases presenting with bilateral polycystic kidneys on prenatal ultrasound by following a diagnostic algorithm.

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.

A prenatal case of Simpson-Golabi-Behmel syndrome type 1 with a 0.26-Mb deletion fragment at Xq26.2 inherited from mother: Case report

RATIONALE

The purpose of this report was to explore how to manage the fetus of Simpson-Golabi-Behmel syndrome type 1 (SGBS1) and to provide a definite diagnosis to guide the following genetic counseling for the pregnancy.

PATIENT CONCERNS

A 24-year-old women, gravida 1, para 0, was 172 cm tall with weight 65 kg. She was referred to our center for counseling due to second-trimester ultrasound screening anomalies at 22 + 5 weeks of gestation age. Meanwhile the ultrasound examination indicated the overgrowth of the fetus. She and her husband were healthy and nonconsanguineous without family history.

DIAGNOSES

The karyotype and copy number variations sequencing (CNV-seq) combined with fetal ultrasound manifestation confirmed the diagnosis of SGBS1.

INTERVENTIONS

No treatment for the fetus.

OUTCOMES

Pregnancy was terminated.

LESSIONS

Once fetal overgrowth and other malformation are revealed in prenatal ultrasound, although without polyhydramnios and organomegaly, SGBS1 should be considered and further genetic testing such as CNV-seq and whole exon sequencing should be conducted to help clinicians provide a definite diagnosis to guide the following genetic counseling and the next pregnancy.

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.