Renal cystic diseases (RCDs) can arise from utero to early adulthood and present with a variety of symptoms including renal, hepatic, and cardiovascular manifestations. It is well known that common RCDs such as autosomal polycystic kidney disease and autosomal recessive kidney disease are linked to genes such as PKD1 and PKHD1, respectively. However, it is important to investigate the genetic pathophysiology of how these gene mutations lead to clinical symptoms and include some of the less-studied RCDs, such as autosomal dominant tubulointerstitial kidney disease, multicystic dysplastic kidney, Zellweger syndrome, calyceal diverticula, and more. We plan to take a thorough look into the genetic involvement and clinical sequalae of a number of RCDs with the goal of helping to guide diagnosis, counseling, and treatment.

Renal cystic diseases are characterized by genetic and phenotypic heterogeneity. Congenital renal cysts can be classified as developmental disorders and are commonly diagnosed prenatally using ultrasonography and magnetic resonance imaging. Progress in molecular diagnostics and availability of exome sequencing procedures allows diagnosis of single-gene disorders in the prenatal period. Two patients with a prenatal diagnosis of polycystic kidney disease are presented in this article. TMEM67 mutations were identified in both fetuses using a whole-exome sequencing (WES) study. In one of them, the phenotypic syndrome diagnosed prenatally was different from that diagnosed in the postnatal period.

Background: Meckel-Gruber syndrome (MKS; OMIM No. 249000) is a rare, in utero lethal disease characterized by occipital encephalocele, polycystic kidneys, and polydactyly. Methodology and Results: In this study, two fetuses diagnosed as having MKS in the prenatal period were evaluated on the basis of ultrasonographic findings, postmortem autopsy findings, and molecular genetic analyses. Using exome sequencing analyses a novel homozygous frameshift variant (NM_015631: c.530delA, p.Lys177Argfs*47) was detected at exon 4 of TCTN3 gene in case 1, and a novel homozygous synonymous variant (NM_025114: c.180G>A, p Lys60Lys) was detected at exon 3 of CEP290 gene in case 2. Case 1 is the first reported case in the literature, which showed the typical MKS clinical feature with a novel frameshift variation in the TCTN3 gene. The variant in case 2 is the first reported synonymous variant of CEP290 gene in the literature, which has been shown to affect splicing in a functional study at the RNA level. Conclusion: TCTN3 gene variants that were rarely associated with the typical MKS phenotype and all cases with these variations have been discussed in the context of genotype-phenotype. The detection of the first synonymous variant of CEP290 gene and the demonstration of its effect on splicing by a functional study are likely to contribute to the molecular etiology of MKS.

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 (MKS) is a rare lethal autosomal recessive disorder with typical anomalies including encephalocele, multicystic renal dysplasia, congenital liver fibrosis, and polydactyly. MKS is caused by mutations of genes localized on different chromosomes. Karyotypes of published Meckel-Gruber syndrome cases are without any aberrations. We present a male fetus with meningoencephalocele, multicystic renal dysplasia, congenital liver fibrosis, and other anomalies. Standard cytogenetic examination of cultured fetal skin and muscle fibroblasts showed mosaic trisomy 17. Homozygous deletion in CC2D2A gene was found by Sanger sequencing. This is to our knowledge the first case of genetically confirmed Meckel-Gruber syndrome with incidental cofinding of mosaic trisomy 17. Abnormal karyotype does not exclude diagnosis of MKS with risk of recurrence 25% in next pregnancy. In the case of anomalies typical for Meckel-Gruber syndrome, genetic analysis is indicated.

Meckel-Gruber syndrome (MKS, OMIM #607361) is a rare pre- or perinatal lethal autosomal recessive ciliopathy caused by mutations in at least 12 known genes. It has a clinical and genetic overlap with other viable ciliopathies, especially Joubert syndrome and Joubert syndrome-related disorders. MKS is characterized by multicystic kidney dysplasia, central nervous system malformations (usually occipital encephalocele), ductal plate malformation of the liver, and postaxial polydactyly.
We identified a homozygous mutation in TMEM67 (MKS3) in a fetus affected by MKS; however, only the mother was a carrier of the respective mutation. Genotyping with polymorphic microsatellite markers and single nucleotide polymorphism (SNP) array revealed a maternal uniparental disomy (UPD) of the entire chromosome 8 (upd(8)mat), harboring TMEM67.
This is the first reported case of UPD as a cause of MKS. The possible underlying mechanisms for uniparental disomy (UPD) are reviewed. Even if rare, awareness of UPD and comprehensive work-up in the case of unexpected homozygosity for a recessive mutation is essential for accurate genetic counseling and assessment of the risk of recurrence.

Meckel-Gruber syndrome (MGS) is a rare autosomal recessive disorder which is characterized by a classic triad of occipital encephalocele, polycystic kidneys and postaxial polydactyly. We describe a case of classic MGS, diagnosed on ultrasonography and genetic analysis, with subsequent confirmation and correlation by fetal autopsy.
La sindrome di Meckel–Gruber (MGS) è una rara anomalia autosomatica recessiva caratterizzata dalla triade classica composta da encefalo occipitale, reni policistici e polidattilìa postassiale. Descriviamo un caso di MGS classica, diagnosticata con ecografia ed analisi genetiche, successivamente confermata dal test autoptico del feto.