Prenatal diagnosis of recurrent Meckel syndrome

Neurosurgical intervention for the Meckel-Gruber Syndrome: A systematic review

INTRODUCTION

Meckel-Gruber Syndrome (MKS) is an autosomal recessive genetic disorder, notable for its triad of occipital encephalocele, polycystic renal dysplasia, and postaxial polydactyly. Identified by Johann Friederich Meckel in 1822, MKS is categorized as a ciliopathy due to gene mutations. Diagnosis is confirmed by the presence of at least two key features. The condition is incompatible with life, leading to death in the womb or shortly after birth. Recent studies have largely focused on the genetic aspects of MKS, with limited information regarding the impact of neurosurgical approaches, particularly in treating encephaloceles.

METHODS

A systematic review was performed according to the PRISMA statement. The PubMed, Embase, and Web of Science databases were consulted for data screening and extraction, which was conducted by two independent reviewers. The search strategy aimed to encompass studies documenting cases of MKS with published reports of encephalocele excisions, and the search strings for all databases were: Meckel-Gruber syndrome OR Meckel Gruber syndrome OR Meckel-gruber OR Meckel Gruber.

RESULTS

The study included 10 newborns with MKS associated with occipital encephalocele or meningocele, all of whom underwent surgical repair of the occipital sac. The mean gestational age at birth was 36 (± 2) weeks. The mean of birth weight was 3.14 (± 0.85) kilograms. The average head circumference at birth was 33.82 cm (± 2.17). The mean diameter of the encephalocele/meningocele was 5.91 (± 1.02) cm. Other common central nervous system abnormalities included hydrocephalus, Dandy-Walker malformation, and agenesis of the corpus callosum. 40% required shunting for hydrocephalus. Surgery to remove the occipital sac occurred at a median age of 2.5 days (1.5-6.5). The most common post-surgical complication was the need for mechanical ventilation. The most common cause of death was pneumonia and the median age at death was 6.66 (0.03-18) months.

CONCLUSION

Our findings suggest that neurosurgical intervention, especially for managing encephaloceles, may offer some improvement in survival, albeit within a context of generally poor prognosis. However, these results should be interpreted with caution.

Retinal ciliopathies through the lens of Bardet-Biedl Syndrome: Past, present and future

The primary cilium is a highly specialized and evolutionary conserved organelle in eukaryotes that plays a significant role in cell signaling and trafficking. Over the past few decades tremendous progress has been made in understanding the physiology of cilia and the underlying pathomechanisms of various ciliopathies. Syndromic ciliopathies consist of a group of disorders caused by ciliary dysfunction or abnormal ciliogenesis. These disorders have multiorgan involvement in addition to retinal degeneration underscoring the ubiquitous distribution of primary cilia in different cell types. Genotype-phenotype correlation is often challenging due to the allelic heterogeneity and pleiotropy of these disorders. In this review, we discuss the clinical and genetic features of syndromic ciliopathies with a focus on Bardet-Biedl syndrome (BBS) as a representative disorder. We discuss the structure and function of primary cilia and their role in retinal photoreceptors. We describe the progress made thus far in understanding the functional and genetic characterization including expression quantitative trait locus (eQTL) analysis of BBS genes. In the future directions section, we discuss the emerging technologies, such as gene therapy, as well as anticipated challenges and their implications in therapeutic development for ciliopathies.

Nephronophthisis-Pathobiology and Molecular Pathogenesis of a Rare Kidney Genetic Disease

The exponential rise in our understanding of the aetiology and pathophysiology of genetic cystic kidney diseases can be attributed to the identification of cystogenic genes over the last three decades. The foundation of this was laid by positional cloning strategies which gradually shifted towards next-generation sequencing (NGS) based screenings. This shift has enabled the discovery of novel cystogenic genes at an accelerated pace unlike ever before and, most notably, the past decade has seen the largest increase in identification of the genes which cause nephronophthisis (NPHP). NPHP is a monogenic autosomal recessive cystic kidney disease caused by mutations in a diverse clade of over 26 identified genes and is the most common genetic cause of renal failure in children. NPHP gene types present with some common pathophysiological features alongside a diverse range of extra-renal phenotypes associated with specific syndromic presentations. This review provides a timely update on our knowledge of this disease, including epidemiology, pathophysiology, anatomical and molecular features. We delve into the diversity of the NPHP causing genes and discuss known molecular mechanisms and biochemical pathways that may have possible points of intersection with polycystic kidney disease (the most studied renal cystic pathology). We delineate the pathologies arising from extra-renal complications and co-morbidities and their impact on quality of life. Finally, we discuss the current diagnostic and therapeutic modalities available for disease management, outlining possible avenues of research to improve the prognosis for NPHP patients.

Meckel-Gruber Syndrome: An Update on Diagnosis, Clinical Management, and Research Advances

Meckel-Gruber syndrome (MKS) is a lethal autosomal recessive congenital anomaly syndrome caused by mutations in genes encoding proteins that are structural or functional components of the primary cilium. Conditions that are caused by mutations in ciliary genes are collectively termed the ciliopathies, and MKS represents the most severe condition in this group of disorders. The primary cilium is a microtubule-based organelle, projecting from the apical surface of vertebrate cells. It acts as an "antenna" that receives and transduces chemosensory and mechanosensory signals, but also regulates diverse signaling pathways, such as Wnt and Shh, that have important roles during embryonic development. Most MKS proteins localize to a distinct ciliary compartment called the transition zone (TZ) that regulates the trafficking of cargo proteins or lipids. In this review, we provide an up-to-date summary of MKS clinical features, molecular genetics, and clinical diagnosis. MKS has a highly variable phenotype, extreme genetic heterogeneity, and displays allelism with other related ciliopathies such as Joubert syndrome, presenting significant challenges to diagnosis. Recent advances in genetic technology, with the widespread use of multi-gene panels for molecular testing, have significantly improved diagnosis, genetic counseling, and the clinical management of MKS families. These include the description of some limited genotype-phenotype correlations. We discuss recent insights into the molecular basis of disease in MKS, since the functions of some of the relevant ciliary proteins have now been determined. A common molecular etiology appears to be disruption of ciliary TZ structure and function, affecting essential developmental signaling and the regulation of secondary messengers.

Meckel-Gruber Syndrome: a population-based study on prevalence, prenatal diagnosis, clinical features, and survival in Europe

Meckel-Gruber Syndrome is a rare autosomal recessive lethal ciliopathy characterized by the triad of cystic renal dysplasia, occipital encephalocele and postaxial polydactyly. We present the largest population-based epidemiological study to date using data provided by the European Surveillance of Congenital Anomalies (EUROCAT) network. The study population consisted of 191 cases of MKS identified between January 1990 and December 2011 in 34 European registries. The mean prevalence was 2.6 per 100,000 births in a subset of registries with good ascertainment. The prevalence was stable over time, but regional differences were observed. There were 145 (75.9%) terminations of pregnancy after prenatal diagnosis, 13 (6.8%) fetal deaths, 33 (17.3%) live births. In addition to cystic kidneys (97.7%), encephalocele (83.8%) and polydactyly (87.3%), frequent features include other central nervous system anomalies (51.4%), fibrotic/cystic changes of the liver (65.5% of cases with post mortem examination) and orofacial clefts (31.8%). Various other anomalies were present in 64 (37%) patients. As nowadays most patients are detected very early in pregnancy when liver or kidney changes may not yet be developed or may be difficult to assess, none of the anomalies should be considered obligatory for the diagnosis. Most cases (90.2%) are diagnosed prenatally at 14.3 ± 2.6 (range 11-36) gestational weeks and pregnancies are mainly terminated, reducing the number of LB to one-fifth of the total prevalence rate. Early diagnosis is important for timely counseling of affected couples regarding the option of pregnancy termination and prenatal genetic testing in future pregnancies.

Meckel-Gruber syndrome: A rare and lethal anomaly with review of literature

Meckel-Gruber syndrome is a rare autosomal recessive lethal malformation characterized by typical manifestations of occipital encephalocele, bilateral polycystic kidneys and post axial polydactyly. The worldwide incidence varies from 1 in 13,250 to 1 in 140,000 live births. Highest incidence was reported in Gujarati Indians. We report a rare case of Meckel-Gruber syndrome and review of literature.

Distribution of myofibroblastic cells in the liver and kidney of Meckel-Gruber syndrome

Meckel-Gruber syndrome (MGS) is a rare disorder characterized by occipital encephalocele, polydactyly and polycystic kidney. Early diagnosis is very important because MGS has a high risk of recurrence and infants with MGS are frequently stillborn or die soon after birth. An autopsy case of MGS is presented and the focus is specifically on the myofibroblastic cells of the liver and polycystic kidney. Although routine histological examination did not reveal hepatic fibrosis, a specific distribution of alpha smooth muscle actin (alpha-SMA)-positive and h-caldesmon (h-CD)-negative stromal cells (myofibroblastic cells) was observed along the limiting plate of the portal area. Furthermore, myofibroblastic cells were focally distributed along the sinusoidal wall and around the bile ducts in the portal area. In the polycystic kidney, the presence of myofibroblastic cells in the stroma between the cystic lesions was also confirmed by electron microscopy. In conclusion, myofibroblastic cells were distributed in the liver and kidney of a patient with MGS and their specific distribution in the liver may be indicative of prestage hepatic fibrosis.

Meckel Gruber syndrome: a first trimester diagnosis of a recurrent case

We report of a case of Meckel Gruber Syndrome (MGS) in a woman, who suffered previously from a pregnancy with the same disorder. MGS, consisting of an occipital encephalocele, bilateral cystic kidneys and postaxial polydactyly, is a rare autosomal recessive disorder, with a recurrence risk of 25%. With the present technology, a targeted ultrasound in the late embryonic or early fetal stages of pregnancy has the potential to diagnose this syndrome. Clinical screening in further pregnancies is of utmost importance and the management of such cases is presented.

Prenatal diagnosis of Meckel syndrome: a case report

OBJECTIVE

To demonstrate the major sonographic findings associated with Meckel syndrome and to emphasize the importance of prenatal sonography in helping to establish the correct diagnosis.

SUBJECTS

Two fetuses with prenatal diagnosis of Meckel syndrome were sonographically evaluated.

RESULTS

Both fetuses were demonstrated to have evidence of renal cystic dysplasia, occipital cephalocele and postaxial polydactyly. One case was diagnosed at 16 weeks of gestation whereas the other was detected at 36 weeks. Of interest, the first case had only unilateral renal cystic dysplasia and contralateral renal agenesis and mild degree of oligohydramnios. The other related anomalies which were not detected prenatally included cerebellar hypoplasia in case 1 and micrognathia in case 2.

CONCLUSION

The main sonographic findings included renal cystic dysplasia, occipital cephalocele and postaxial polydactyly.

Antenatal Diagnosis of Infantile Polycystic Kidney Disease in a Twin Gestation

Infantile polycystic kidney disease is an autosomal recessive disorder characterized by bilateral and symmetric enlargement of the kidneys. The renal parenchyma is characteristically replaced by cystic dilatation of the collecting tubules.1 This case report discusses the sonographic criteria used to antenatally diagnose infantile polycystic kidney disease.