Sonic Hedgehog Signaling and VACTERL Association

Cartilage within lipomyelomeningocele and ulnar longitudinal deficiency syndrome as VACTERL association, alliance in SHH/GLI3, and Wnt pathway: illustrative case

BACKGROUND

Lipomyelomeningocele associated with an ulnar club hand in the spectrum of VACTERL association ([costo-]vertebral abnormalities; anal atresia; cardiac defects; tracheal-esophageal abnomalities, including atresia, stenosis, and fistula; renal and radial abnormalities; limb abnormalities; single umbilical artery) is a very rare and infrequently reported phenomenon. Within the fat mass of the lipoma, it is not common to find a well-defined cartilaginous mass with no attachments to the surrounding tissue.

OBSERVATIONS

The authors present the case of a 3-month-old male with low-back swelling that was off-center to the left, accompanied by a left short forearm displaying outward bowing. Echocardiography showed an atrial septal defect. This rare VACTERL association comprises lipomyelomeningocele, atrial septal defect, and ulnar longitudinal deficiency syndrome. During surgical intervention for the lipoma, a well-defined cartilaginous mass was discovered within the adipose tissue.

LESSONS

The manifestation of VACTERL association can be partially explained by the Shh/Gli and Wnt pathway defects. It is prudent to screen children with neural tube defects to be aware of any associated syndromes. This case is very rare, and the literature has contained no prior report on the VACTERL association of lipomyelomeningocele, atrial septal defect, and ulnar longitudinal deficiency.

Perturbation of 3D nuclear architecture, epigenomic dysregulation and aging, and cannabinoid synaptopathy reconfigures conceptualization of cannabinoid pathophysiology: part 1-aging and epigenomics

Much recent attention has been directed toward the spatial organization of the cell nucleus and the manner in which three-dimensional topologically associated domains and transcription factories are epigenetically coordinated to precisely bring enhancers into close proximity with promoters to control gene expression. Twenty lines of evidence robustly implicate cannabinoid exposure with accelerated organismal and cellular aging. Aging has recently been shown to be caused by increased DNA breaks. These breaks rearrange and maldistribute the epigenomic machinery to weaken and reverse cellular differentiation, cause genome-wide DNA demethylation, reduce gene transcription, and lead to the inhibition of developmental pathways, which contribute to the progressive loss of function and chronic immune stimulation that characterize cellular aging. Both cell lineage-defining superenhancers and the superanchors that control them are weakened. Cannabis exposure phenocopies the elements of this process and reproduces DNA and chromatin breakages, reduces the DNA, RNA protein and histone synthesis, interferes with the epigenomic machinery controlling both DNA and histone modifications, induces general DNA hypomethylation, and epigenomically disrupts both the critical boundary elements and the cohesin motors that create chromatin loops. This pattern of widespread interference with developmental programs and relative cellular dedifferentiation (which is pro-oncogenic) is reinforced by cannabinoid impairment of intermediate metabolism (which locks in the stem cell-like hyper-replicative state) and cannabinoid immune stimulation (which perpetuates and increases aging and senescence programs, DNA damage, DNA hypomethylation, genomic instability, and oncogenesis), which together account for the diverse pattern of teratologic and carcinogenic outcomes reported in recent large epidemiologic studies in Europe, the USA, and elsewhere. It also accounts for the prominent aging phenotype observed clinically in long-term cannabis use disorder and the 20 characteristics of aging that it manifests. Increasing daily cannabis use, increasing use in pregnancy, and exponential dose-response effects heighten the epidemiologic and clinical urgency of these findings. Together, these findings indicate that cannabinoid genotoxicity and epigenotoxicity are prominent features of cannabis dependence and strongly indicate coordinated multiomics investigations of cannabinoid genome-epigenome-transcriptome-metabolome, chromatin conformation, and 3D nuclear architecture. Considering the well-established exponential dose-response relationships, the diversity of cannabinoids, and the multigenerational nature of the implications, great caution is warranted in community cannabinoid penetration.

A Novel VACTERL Assessment Tool to Facilitate Counseling for Expectant Families

INTRODUCTION

VACTERL is defined as 3 or more of the following congenital defects: vertebral, anorectal, cardiac, tracheoesophageal (TE), renal, and limb. The purpose of this study was to create an easy-to-use assessment tool to help providers counsel expecting families regarding the likelihood of additional anomalies and postnatal outcomes.

METHODS

Employing the Kids' Inpatient Database from 2003-2016, neonates (<29 days old) with VACTERL were identified using ICD-9-CM and ICD-10-CM codes. For each unique combination of VACTERL, multivariable logistic regression was used to estimate inpatient mortality, and Poisson regression was used to estimate length-of-stay during the initial hospitalization.

RESULTS

The assessment tool used in this study is available at https://choc-trauma.shinyapps.io/VACTERL. 1,886 of 11,813,782 (0.016%) neonates presented with VACTERL. 32% weighed <1,750 g, and 239 (12.7%) died prior to discharge. Associated with mortality were limb anomaly (1.8 [1.01-3.22], p < 0.05), prematurity (1.99 [1.14-3.47], p < 0.02), and weight <1,750 g (2.19 [1.25-3.82], p < 0.01). Median length-of-stay was 14 days (IQR: 7-32). Associated with increased length-of-stay were cardiac defect (1.47 [1.37-1.56], p < 0.001), vertebral anomaly (1.1 [1.05-1.14], p < 0.001), TE fistula (1.73 [1.66-1.81], p < 0.001), anorectal malformation (1.12 [1.07-1.16], p < 0.001), and weight <1,750 g (1.65 [1.57-1.73], p < 0.001).

CONCLUSION

This novel assessment tool may help providers counsel families confronting a VACTERL diagnosis.

A missense variant at the RAC1-PAK1 binding site of RAC1 inactivates downstream signaling in VACTERL association

RAC1 at 7p22.1 encodes a RAC family small GTPase that regulates actin cytoskeleton organization and intracellular signaling pathways. Pathogenic RAC1 variants result in developmental delay and multiple anomalies. Here, exome sequencing identified a rare de novo RAC1 variant [NM_018890.4:c.118T > C p.(Tyr40His)] in a male patient. Fetal ultrasonography indicated the patient to have multiple anomalies, including persistent left superior vena cava, total anomalous pulmonary venous return, esophageal atresia, scoliosis, and right-hand polydactyly. After birth, craniofacial dysmorphism and esophagobronchial fistula were confirmed and VACTERL association was suspected. One day after birth, the patient died of respiratory failure caused by tracheal aplasia type III. The molecular mechanisms of pathogenic RAC1 variants remain largely unclear; therefore, we biochemically examined the pathophysiological significance of RAC1-p.Tyr40His by focusing on the best characterized downstream effector of RAC1, PAK1, which activates Hedgehog signaling. RAC1-p.Tyr40His interacted minimally with PAK1, and did not enable PAK1 activation. Variants in the RAC1 Switch II region consistently activate downstream signals, whereas the p.Tyr40His variant at the RAC1-PAK1 binding site and adjacent to the Switch I region may deactivate the signals. It is important to accumulate data from individuals with different RAC1 variants to gain a full understanding of their varied clinical presentations.

Hedgehog signaling activates a mammalian heterochronic gene regulatory network controlling differentiation timing across lineages

Many developmental signaling pathways have been implicated in lineage-specific differentiation; however, mechanisms that explicitly control differentiation timing remain poorly defined in mammals. We report that murine Hedgehog signaling is a heterochronic pathway that determines the timing of progenitor differentiation. Hedgehog activity was necessary to prevent premature differentiation of second heart field (SHF) cardiac progenitors in mouse embryos, and the Hedgehog transcription factor GLI1 was sufficient to delay differentiation of cardiac progenitors in vitro. GLI1 directly activated a de novo progenitor-specific network in vitro, akin to that of SHF progenitors in vivo, which prevented the onset of the cardiac differentiation program. A Hedgehog signaling-dependent active-to-repressive GLI transition functioned as a differentiation timer, restricting the progenitor network to the SHF. GLI1 expression was associated with progenitor status across germ layers, and it delayed the differentiation of neural progenitors in vitro, suggesting a broad role for Hedgehog signaling as a heterochronic pathway.

VACTERL syndrome with late presentation of annular pancreas with duodenal web: Case report

VACTERL Syndrome affects multiple body systems and can include various anomalies of the Vertebral column, Anus and/or rectum, heart (Cardiac), Tracheo-Esophagus, kidneys (Renal), and Limbs. Patients with VACTERL syndrome are at increased risk of having a congenital duodenal obstruction that may be extrinsic in the form of an annular pancreas or intrinsic in the form of duodenal atresia, stenosis or web. Simultaneous presentation of both the annular pancreas and duodenal web is a rare clinical entity and typically presents in neonates. However, late presentation of annular pancreas combined with a duodenal web is exceedingly uncommon. We present a case of late diagnosis of annular pancreas with duodenal web resulting in an entrapped ingested foreign body.

European epidemiological patterns of cannabis- and substance-related congenital cardiovascular anomalies: geospatiotemporal and causal inferential study

As prenatal and community cannabis exposures have recently been linked with congenital heart disease (CHD), it was of interest to explore these associations in Europe in a causal framework and space-time context. Congenital anomaly data from Eurocat, drug-use data from the European Monitoring Centre for Drugs and Drug Addiction, and income from the World Bank. Countries with rising daily cannabis use had in general higher congenital anomaly rates over time than those without (time: status interaction: β-Est. = 0.0267, P = 0.0059). At inverse probability-weighted panel regression, cannabis terms were positive and significant for CHD, severe CHD, atrial septal defect, ventricular septal defect, atrioventricular septal defect, patent ductus arteriosus, tetralogy of Fallot, vascular disruptions, double outlet right ventricle, transposition of the great vessels, hypoplastic right heart, and mitral valve anomalies from 1.75 × 10^-19, 4.20 × 10^-11, <2.2 × 10^-16, <2.2 × 10^-16, 1.58 × 10^-12, 4.30 × 10^-9, 4.36 × 10^-16, 3.50 × 10^-8, 5.35 × 10^-12, <2.2 × 10^-16, 5.65 × 10^-5 and 6.06 × 10^-10. At spatial regression, terms including cannabis were positive and significant for this same list of anomalies from 0.0038, 1.05 × 10^-10, 0.0215, 8.94 × 10^-6, 1.23 × 10^-5, 2.05 × 10^-5, 1.07 × 10^-6, 8.77 × 10^-5, 9.11 × 10^-6, 0.0001, 3.10 × 10^-7 and 2.17 × 10^-7. 92.6% and 75.2% of 149 E-value estimates and minimum E-values were in high zone >9; 100.0% and 98.7% >1.25. Data show many congenital cardiac anomalies exhibit strong bivariate relationships with metrics of cannabis exposure. Causal inferential modelling for the twelve anomalies selected demonstrated convincing evidence of robust relationships to cannabis which survived adjustment and fulfilled epidemiological criteria for causal relationships. Space-time regression was similarly confirmatory. Epigenomic pathways constitute viable potential mechanisms. Given exponential genotoxic dose-response effects, careful and astute control of cannabinoid penetration is indicated.

VACTERL Association with Situs Inversus Totalis: A Unique Combination

BACKGROUND

VACTERL association is a sporadic, nonrandom series of congenital malformations diagnosed by the presence of three or more of the following: vertebral malformations, anal atresia, cardiac defects, tracheoesophageal fistula, renal malformations, and limb malformations. Situs inversus totalis (SIT) and esophageal malformations are rarely associated. This is the first reported case in North America of VACTERL association with SIT.

IMPLICATIONS FOR PRACTICE

Respiratory distress in the term infant requires full exploration of all possible causes because the etiology may be far more complex than routinely diagnosed respiratory distress syndrome. This particular case demonstrates physical exam findings and supportive imaging that would be observed in infants with VACTERL association and with SIT, highlighting considerations when, rarely, both occur simultaneously.

Interkinetic nuclear migration in the tracheal and esophageal epithelia of the mouse embryo: Possible implications for tracheo-esophageal anomalies

Interkinetic nuclear migration (INM) is a cell polarity-based phenomenon in which progenitor cell nuclei migrate along the apico-basal axis of the pseudostratified epithelium in synchrony with the cell cycle. INM is suggested to be at least partially cytoskeleton-dependent and to regulate not only the proliferation/differentiation of stem/progenitor cells but also the localized/overall size and shape of organs/tissues. INM occurs in all three of the germ-layer derived epithelia, including the endoderm-derived gut. However, INM has not been documented in the esophagus and respiratory tube arising from the anterior foregut. Esophageal atresia with or without trachea-esophageal fistula (EA/TEF) is a relatively common developmental defect. Transcription factors and signaling molecules have been implicated in EA/TEF, but the etiology of EA/TEF-which has been suggested to involve cell polarity-related mechanisms-remains highly controversial. In the present study, we first examined whether INM exists in the trachea and esophagus of mouse embryos at embryonic day 11.5 (E11.5), just after separation of the two tubes from the anterior foregut. By labeling the DNA-synthesizing stem cell nuclei with 5-ethynyl-2'-deoxyuridine, a nucleotide analogue, and statistically analyzing chronological changes in the distribution pattern of the labeled nuclei by using multidimensional scaling, we showed the existence of INM in both the esophagus and trachea, with differences in the INM magnitude and cycle pattern. We further showed morphological changes from the INM-based pseudostratified single layer to the stratified multilayer in the esophageal epithelium in association with a temporal loss/perturbation of AB polarity, suggesting a possible relation with the pathogenesis of EA/TEF.

Genetic Syndromes Affecting Kidney Development

Renal anomalies are common birth defects that may manifest as a wide spectrum of anomalies from hydronephrosis (dilation of the renal pelvis and calyces) to renal aplasia (complete absence of the kidney(s)). Aneuploidies and mosaicisms are the most common syndromes associated with CAKUT. Syndromes with single gene and renal developmental defects are less common but have facilitated insight into the mechanism of renal and other organ development. Analysis of underlying genetic mutations with transgenic and mutant mice has also led to advances in our understanding of mechanisms of renal development.

Vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association with Mayer-Rokitansky-Küster-Hauser syndrome in co-occurrence: two case reports and a review of the literature

BACKGROUND

The vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome are rare conditions. We aimed to present two cases with the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser co-occurrence from our local surgical center and through a systematic literature search detect published cases. Furthermore, we aimed to collect existing knowledge in the embryopathogenesis and genetics in order to discuss a possible link between the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome.

CASE PRESENTATION

Our first case was a white girl delivered by caesarean section at 37 weeks of gestation; our second case was a white girl born at a gestational age of 40 weeks. A co-occurrence of vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome was diagnosed in both cases. We performed a systematic literature search in PubMed ((VACTERL) OR (VATER)) AND ((MRKH) OR (Mayer-Rokitansky-Küster-Hauser) OR (mullerian agenesis) OR (mullerian aplasia) OR (MURCS)) without limitations. A similar search was performed in Embase and the Cochrane library. We added two cases from our local center. All cases (n = 9) presented with anal atresia and renal defect. Vertebral defects were present in eight patients. Rectovestibular fistula was confirmed in seven patients. Along with the uterovaginal agenesis, fallopian tube aplasia appeared in five of nine cases and in two cases ovarian involvement also existed.

CONCLUSIONS

The co-occurrence of the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome is extremely rare. This group of patients has unusual phenotypic characteristics. The long-term outcome after treatment of defects is not well reported. A single unifying cause is not known and the etiology probably includes both genetic and non-genetic causes. We stress the importance of future studies to optimized treatment, follow-up, and etiology.

Genetics of Combined Pituitary Hormone Deficiency: Roadmap into the Genome Era

The genetic basis for combined pituitary hormone deficiency (CPHD) is complex, involving 30 genes in a variety of syndromic and nonsyndromic presentations. Molecular diagnosis of this disorder is valuable for predicting disease progression, avoiding unnecessary surgery, and family planning. We expect that the application of high throughput sequencing will uncover additional contributing genes and eventually become a valuable tool for molecular diagnosis. For example, in the last 3 years, six new genes have been implicated in CPHD using whole-exome sequencing. In this review, we present a historical perspective on gene discovery for CPHD and predict approaches that may facilitate future gene identification projects conducted by clinicians and basic scientists. Guidelines for systematic reporting of genetic variants and assigning causality are emerging. We apply these guidelines retrospectively to reports of the genetic basis of CPHD and summarize modes of inheritance and penetrance for each of the known genes. In recent years, there have been great improvements in databases of genetic information for diverse populations. Some issues remain that make molecular diagnosis challenging in some cases. These include the inherent genetic complexity of this disorder, technical challenges like uneven coverage, differing results from variant calling and interpretation pipelines, the number of tolerated genetic alterations, and imperfect methods for predicting pathogenicity. We discuss approaches for future research in the genetics of CPHD.

Identification and Validation of Novel Hedgehog-Responsive Enhancers Predicted by Computational Analysis of Ci/Gli Binding Site Density

The Hedgehog (Hh) signaling pathway directs a multitude of cellular responses during embryogenesis and adult tissue homeostasis. Stimulation of the pathway results in activation of Hh target genes by the transcription factor Ci/Gli, which binds to specific motifs in genomic enhancers. In Drosophila, only a few enhancers (patched, decapentaplegic, wingless, stripe, knot, hairy, orthodenticle) have been shown by in vivo functional assays to depend on direct Ci/Gli regulation. All but one (orthodenticle) contain more than one Ci/Gli site, prompting us to directly test whether homotypic clustering of Ci/Gli binding sites is sufficient to define a Hh-regulated enhancer. We therefore developed a computational algorithm to identify Ci/Gli clusters that are enriched over random expectation, within a given region of the genome. Candidate genomic regions containing Ci/Gli clusters were functionally tested in chicken neural tube electroporation assays and in transgenic flies. Of the 22 Ci/Gli clusters tested, seven novel enhancers (and the previously known patched enhancer) were identified as Hh-responsive and Ci/Gli-dependent in one or both of these assays, including: Cuticular protein 100A (Cpr100A); invected (inv), which encodes an engrailed-related transcription factor expressed at the anterior/posterior wing disc boundary; roadkill (rdx), the fly homolog of vertebrate Spop; the segment polarity gene gooseberry (gsb); and two previously untested regions of the Hh receptor-encoding patched (ptc) gene. We conclude that homotypic Ci/Gli clustering is not sufficient information to ensure Hh-responsiveness; however, it can provide a clue for enhancer recognition within putative Hedgehog target gene loci.

Analysis of renal anomalies in VACTERL association

BACKGROUND

VACTERL association refers to a combination of congenital anomalies that can include: vertebral anomalies, anal atresia, cardiac malformations, tracheo-esophageal fistula with esophageal atresia, renal anomalies (typically structural renal anomalies), and limb anomalies.

METHODS

We conducted a description of a case series to characterize renal findings in a cohort of patients with VACTERL association. Out of the overall cohort, 48 patients (with at least three component features of VACTERL and who had abdominal ultrasound performed) met criteria for analysis. Four other patients were additionally analyzed separately, with the hypothesis that subtle renal system anomalies may occur in patients who would not otherwise meet criteria for VACTERL association.

RESULTS

Thirty-three (69%) of the 48 patients had a clinical manifestation affecting the renal system. The most common renal manifestation (RM) was vesicoureteral reflux (VUR) in addition to a structural defect (present in 27%), followed by unilateral renal agenesis (24%), and then dysplastic/multicystic kidneys or duplicated collected system (18% for each). Twenty-two (88%) of the 25 patients with a structural RM had an associated anorectal malformation. Individuals with either isolated lower anatomic anomalies, or both upper and lower anatomic anomalies were not statistically more likely to have a structural renal defect than those with isolated upper anatomic anomalies (p = 0.22, p = 0.284, respectively).

CONCLUSION

Given the high prevalence of isolated VUR in our cohort, we recommend a screening VCUG or other imaging modality be obtained to evaluate for VUR if initial renal ultrasound shows evidence of obstruction or renal scarring, as well as ongoing evaluation of renal health.

Maternal diabetes modulates kidney formation in murine progeny: the role of hedgehog interacting protein (HHIP)

AIMS/HYPOTHESIS

We hypothesised that maternal diabetes impairs kidney formation in offspring via augmented expression of hedgehog interacting protein (HHIP). Our gene-array results were performed in neonatal kidneys from our murine model of maternal diabetes and indicated that Hhip expression was significantly modulated by maternal diabetes.

METHODS

We systematically examined the functional role of HHIP in kidney formation in our murine maternal diabetes model and elucidated the potential mechanisms related to dysnephrogenesis in vitro.

RESULTS

The kidneys of the offspring of diabetic dams, compared with those of the offspring of control non-diabetic dams, showed retardation of development--small kidneys and less ureteric bud (UB) branching morphogenesis. Augmented HHIP expression was observed in the offspring of diabetic dams, initially localised to differentiated metanephric mesenchyme and UB epithelium and subsequently in maturing glomerular endothelial and tubulointerstitial cells. The heightened HHIP targeting TGF-β1 signalling was associated with dysmorphogenesis. In vitro, HHIP overexpression decreased sonic hedgehog and paired box gene 2 proteins (SHH and PAX2, respectively) and increased transcriptional nuclear factor-kappa B (NFκB, p50/p65), phosphorylation of p53, and TGF-β1 expression. In contrast, overexpression of PAX2 inhibited HHIP and NFκB and activated SHH, N-myc and p27(Kip1) expression. Moreover, high glucose stimulated HHIP expression, and then targeted TGF-β1 signalling. Thus, PAX2, via a negative autocrine feedback mechanism, attenuated the stimulatory effect of high glucose on HHIP expression.

CONCLUSIONS/INTERPRETATION

Maternal diabetes modulates kidney formation in young progeny mediated, at least in part, via augmented HHIP expression.