Multiple fetal anomalies associated with subtle subtelomeric chromosomal rearrangements

Prenatal dispositions and genetic analysis of monozygotic female twins with suprasellar cysts and hydrocephalus: A case report

INTRODUCTION

We present a unique case of monozygotic female twins with virtually identical clinical and radiological presentations of supratentorial hydrocephalus and cystic formations from the suprasellar cistern.

DISCUSSION

Evaluating genetic predispositions and prenatal exposures is crucial for hydrocephalus in twins. Familial cases imply a genetic contribution to the development of these anomalies, including chromosomal abnormalities and specific variants linked to arachnoid cyst formation in various syndromes. Extensive genetic analyses found no pathogenic variants in the twins. Prenatal exposure to anti-epileptic medication was known during pregnancy and may be associated with fetal abnormalities, but not central nervous system (CNS) malformations, and was therefore not considered the cause of the condition in the twins. The twins presenting simultaneously with hydrocephalus caused by suprasellar cysts (SAC) underwent a two-step surgical management: initial ventriculoperitoneal shunt (VPS) placement followed by fenestration. Postoperative imaging showed cyst reduction, but a secondary VPS was necessary in both cases.

CONCLUSION

Genetic analysis is less likely to identify a monogenic etiology in non-syndromic cases of SACs, which are assumed to be multifactorial. There is no established evidence linking a teratogenic effect of anti-epileptic drugs to CNS malformations. Moreover, the surgical treatment of this complex condition constitutes a point of discussion.

Ultrasound and magnetic resonance imaging features of fetal intracranial cystic lesions: A pictorial essay

This pictorial essay focuses on ultrasound (US) and magnetic resonance imaging (MRI) features of fetal intracranial cysts. Intracranial cysts are common findings in prenatal imaging, and if great attention is paid to their size, location, and imaging features, they can be diagnosed accurately. They are usually detected by fetal ultrasound exams. However, when ultrasound data on cystic lesion characteristics is insufficient, MRI and fetal neurosonogram are the best options for detecting other associated anomalies. The prognosis is highly dependent on their location and whether they are associated with other fetal anomalies.

Prenatal diagnosis of arachnoid cysts: a case series and systematic review

INTRODUCTION

Primary cysts are believed to arise from the splitting of the arachnoid membrane during prenatal development and can be diagnosed in utero. Prenatal diagnosis is uncommon; therefore, the evidence base for counselling expectant mothers is limited. The purpose of this article is to present a case series and review the current literature on prenatally diagnosed arachnoid cysts.

METHOD

A keyword search of hospital electronic records was performed for all patients with a prenatally diagnosed arachnoid cyst at a tertiary neurosurgical centre. Case notes were reviewed for all patients diagnosed between 2005 and 2017. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to structure a systematic review of all English language articles published up to May 2018.

RESULTS

A total of eight eligible patients were identified from our own records and 123 from the literature. Sixty-eight per cent of patients had a normal outcome. Sixty-three per cent of patients underwent surgical intervention which was not associated with abnormal outcome. The diagnosis of syndromic/genetic diagnosis (p < 0.001) and the presence of other intra-cranial anatomical abnormalities (p = 0.05) were significant predictors of abnormal outcome.

CONCLUSION

The pathogenesis and prognosis of a prenatal arachnoid cyst diagnosis remain unclear. These results suggest favourable outcomes from simple cysts without associated abnormalities and expectant mothers should be counselled accordingly. A wider prospective review is required to better established evidence-based practice.

Outcome of 12 antenatally diagnosed fetal arachnoid cysts: case series and review of the literature

OBJECTIVES

To investigate the natural history, associated abnormalities and outcome of 12 fetuses with arachnoid cyst diagnosed antenatally by ultrasound and magnetic resonance imaging and to compare the outcome with cases in the literature.

METHODS

A retrospective study of all cases of antenatally detected fetal arachnoid cysts was performed in patients referred to a tertiary unit between 2007 and 2013. Associated abnormalities, pregnancy outcome and postnatal follow-up were analyzed. All papers about prenatally diagnosed arachnoid cysts, of the last 30 years, were evaluated (search terms in Pubmed: "prenatal diagnosis", "Arachnoid Cysts").

RESULTS

Fetal arachnoid cysts were diagnosed in 12 fetuses, 9 were females. The mean gestational age of diagnosis was 28 1/7 (range 19 1/7-34 2/7 weeks). A total of 9 cases were supratentorial, 3 were located in the posterior fossa. In 10 cases a fetal MRI was performed which confirmed brain compression in 4 out of 5 supratentorial arachnoid cyst. MRI did not reveal other malformations nor signs of nodular heterotopia. Only one fetus presented with additional major anomalies (bilateral ventricumomegaly of >20 mm and rhombencephalosynapsis) leading to a termination of pregnancy. Two neonates underwent endoscopic fenestration of the arachnoid cyst in the first week of life with no additional intervention in childhood. All but one (10/11) had a favorable postnatal outcome. This child suffered from visual impairment at autism was diagnosed at the age of 5. One child had a surgical correction of strabismus later in childhood. In one child the infratentorial arachnoid cyst regressed spontaneously on ultrasound and MRI in the postnatal period.

CONCLUSIONS

The majority of arachnoid cysts in this series are of benign origin and remain stable. Based on the current series and the review of the literature, in the absence of other associated anomalies and when the karyotype is normal, the postnatal overall and neurological outcome is favorable. Large suprasellar arachnoid cysts however, may cause visual impairment and endocrinological disturbances. Rarely associated cerebral or cerebellar malformations are present. Modern postnatal management of suprasellar arachnoid cyst consists of endoscopic cystoventriculostomy.

Enlarging arachnoid cyst: a false alarm for infants

PURPOSE

The natural history of change in size of arachnoid cysts (ACs) is an unsettled issue. This leads to confusion in deciding treatment strategies of incidental, asymptomatic AC in children, since the risks and complications of surgery are not negligible. The aim of the present study was to elucidate the clinical significance of change in size of AC in young children.

METHODS

From 2000 to 2008, 86 patients younger than 5 years with AC documented on brain imaging were included. They were divided into four different age groups (group I: 0-0.5 year, group II: 0.5-1 year, group III: 1-3 years, group IV: 3-5 years). The temporal changes in size of the AC on consecutive ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) of each patient were measured and plotted as individual graphs. Natural progression of AC size was assessed by evaluation of the pattern of each graph.

RESULTS

Seventeen patients showed enlargement of AC during follow-up; 14 patients were younger than 1 year. None of the patients in group IV showed enlargement during follow-up. Overall, 11 of the 17 patients with demonstrated AC enlargement were not operated on. In six patients, AC enlargement ceased, and spontaneous regression was observed in three patients. The remaining two untreated patients had shown asymptomatic increase in size at last follow-up. Statistical analysis revealed age at diagnosis to be the only significant factor affecting cyst enlargement.

CONCLUSION

Asymptomatic enlargement of AC in infants may not be an indication for surgical intervention. Close follow-up is a viable option for such children.

A retrospective study by oligonucleotide array-CGH analysis in 50 fetuses with multiple malformations

OBJECTIVE

To retrospectively define the frequency and the nature of submicroscopic chromosomal imbalances among fetuses with multiple congenital anomalies (MCA).

METHODS

We used oligonucleotide arrays to perform comparative genomic hybridization after termination of pregnancy in 50 polymalformated fetuses with a normal karyotype. These fetuses presented with at least three significant malformations (42 cases) or a severe brain anomaly (eight cases).

RESULTS

We identified a deleterious copy number variation (CNV) in five fetuses (10%). De novo genomic imbalances identified in this study consisted of a 6qter deletion in a fetus with brain and renal malformations, a mosaicism for a 8p tetrasomy in a fetus with agenesis of corpus callosum, growth retardation, mild facial dysmorphic features, and vertebral anomalies, a 17p13.3 deletion in a fetus with a complex brain malformation, and a partial 11p trisomy in a fetus with severe growth retardation and oligoamnios. In one case, we identified a partial 17q trisomy resulting from malsegregation of a cryptic-balanced translocation.

CONCLUSIONS

This study shows that array comparative genomic hybridization (aCGH) is particularly effective for identifying the molecular basis of the disease phenotype in fetuses with multiple anomalies. Our study should help to define clinical relevant regions that would need to be included in targeted arrays designed for prenatal testing.

Prenatal diagnosis of arachnoid cysts

Arachnoid cysts are a rare central nervous system malformation, representing only 1% of all intracranial masses in newborns. Primary (congenital) arachnoid cysts are benign accumulation of clear fluid between the dura and the brain substance throughout the cerebrospinal axis in relation to the arachnoid membrane and do not communicate with the subarachnoid space. Secondary (acquired) arachnoid cysts result from hemorrhage, trauma, and infection and usually communicate with the subarachnoid space. The common locations of arachnoid cysts are the surface of the brain at the level of main brain fissures, such as sylvian, rolandic and interhemispheric fissures, sella turcica, the anterior cranial fossa, and the middle cranial fossa. Arachnoid cysts may be associated with ventriculomegaly and dysgenesis of corpus callosum. Prenatal ultrasound and magnetic resonance imaging have led to the increased diagnosis of fetal arachnoid cysts. This article provides a thorough review of fetal arachnoid cysts, including prenatal diagnosis, differential diagnosis and associated chromosomal abnormalities, as well as comprehensive illustrations of perinatal imaging findings of fetal arachnoid cysts. Prenatal diagnosis of intracranial hypoechoic lesions should include a differential diagnosis of arachnoid cysts and prompt genetic investigations.

Posterior fossa malformation in fetuses: a report of 56 further cases and a review of the literature

OBJECTIVE

The purposes of this study were to determine the outcome of fetuses diagnosed as having a posterior fossa abnormality (PFA) and to find out if there are associated features helpful in determining the prognosis.

METHODS

This is a retrospective study of all posterior fossa abnormalities detected prenatally in our Units within the last 10 years. Fifty six patients were selected. Outcome data was collected from the Clinical Genetics Department records and the attending obstetrician or pediatrician.

RESULTS

An enlarged cisterna magna (ECM, diameter greater than 10 mm at 18-23 gw) was detected in 22 fetuses, which was isolated in 14 cases. All the patients followed-up (n = 11) with isolated ECM were normal at birth (100%). Non-isolated ECM was present in 8 cases. Further information was available in 7, 5 (71%) of whom had a poor outcome. A Dandy Walker complex abnormality (DWC) was detected in 34 patients. The majority of them had a poor prognosis, 54% if isolated and 84% if non-isolated.

CONCLUSIONS

Isolated ECM detected on prenatal scans has a favourable outcome, while DWC is associated with a very high chance of a poor prognosis.

Subtelomeric rearrangements and 22q11.2 deletion syndrome in anomalous growth-restricted fetuses with normal or balanced G-banded karyotype

OBJECTIVE

To determine the frequencies of cryptic subtelomeric rearrangements and 22q11.2 deletion in anomalous growth-restricted fetuses with normal or balanced G-banded karyotypes.

METHODS

This was a study of 27 consecutive fetuses at a median gestational age of 26 (range, 19-33) weeks, that had intrauterine growth restriction (IUGR) as well as at least one major structural anomaly, and a normal or balanced G-banded karyotype. The median maternal age was 29 (range, 17-39) years. Fluorescence z in-situ hybridization (FISH) diagnosis of the cultured amniocytes with the probe TUPLE 1, and then the Chromoprobe Multiprobe-T system were used, respectively, to screen for the frequency of 22q11.2 deletion syndrome and subtelomeric rearrangements involving the 41 unique chromosome ends (i.e. excluding the five short arms of acrocentric autosomes (no. 13, 14, 15, 21 and 22)). Those that had suspected deleted subtelomeres were reanalyzed with a specific subtelomeric probe, TelVysion.

RESULTS

Of the 27 fetuses, three (11%) were affected with 22q11.2 deletion syndrome and two (7.4%) had subtelomeric deletions (one monosomy 21q22.3, one monosomy 1p36.3). Of the 11 fetuses with congenital heart defects, three (27.3%) had 22q11.2 deletion syndrome and one (9.1%) had monosomy 1p36.3. In the remaining 16 fetuses without congenital heart defects, none had 22q11.2 deletion syndrome. However, one (6.3%) had cryptic rearrangement involving subtelomeres.

CONCLUSION

Prenatal subtelomeric FISH screening is technically feasible using cultured amniocytes. We propose that 22q11.2 deletion syndrome and cryptic subtelomere rearrangements may be important etiologies of fetuses with IUGR and at least one structural anomaly, along with a normal karyotype or one that is balanced by traditional G-banding. Fetuses with congenital heart defects and IUGR should undergo FISH to exclude 22q11.2 deletion syndrome. In fetuses with IUGR and at least one major structural anomaly but without congenital heart defects, screening of subtelomeric rearrangements may contribute to further elucidation of the underlying etiology.

The use of subtelomeric probes to study mental retardation

In this chapter, we focus on the genetic basis of mental retardation (MR), specifically the use of subtelomeric probes to provide new diagnoses in idiopathic MR. We discuss both the background to the clinical demand for diagnoses and the technological advances that culminated in the development of subtelomeric testing strategies. We explain the theory behind these strategies and briefly outline the protocols involved, giving the advantages, limitations, and pitfalls of the analyses. Finally, we give an overview of the MR subtelomeric studies to date and how subtelomeric testing has become a widely used tool in clinical diagnostic laboratories, particularly in the diagnosis of unexplained MR, but also in other fields of clinical medicine. The conclusion addresses the overall impact that subtelomeric testing has had on the diagnosis of MR, the implications for patients and their families, and future research avenues for exploring the genetic causes of MR and improving our overall understanding of neurocognitive development.

Use of subtelomeric fluorescence in situ hybridization in cytogenetic diagnosis

During the last few years there has been an increasing number of reports of chromosomal abnormalities identified by subtelomeric fluorescence in situ hybridization testing in children with unexplained mental retardation. As more children are identified with subtelomeric deletions, duplications, and cryptic unbalanced rearrangements by this testing, questions have arisen regarding the appropriate use of this new technology. A review of current knowledge regarding the clinical phenotypes seen in these patients as well as of newer information regarding the use of this new cytogenetic test in areas outside clinical genetics may help to determine which patients would benefit from its use.