Clinical characterization of autosomal dominant and recessive variants of Robinow syndrome

Craniofacial studies in chicken embryos confirm the pathogenicity of human FZD2 variants associated with Robinow syndrome

Robinow syndrome is a rare disease caused by variants of seven WNT pathway genes. Craniofacial features include widening of the nasal bridge and jaw hypoplasia. We used the chicken embryo to test whether two missense human FZD2 variants (1301G>T, p.Gly434Val; 425C>T, p.Pro142Lys) were sufficient to change frontonasal mass development. In vivo, the overexpression of retroviruses with wild-type or variant human FZD2 inhibited upper beak ossification. In primary cultures, wild-type and variant human FZD2 significantly inhibited chondrogenesis, with the 425C>T variant significantly decreasing activity of a SOX9 luciferase reporter compared to that for the wild type or 1301G>T. Both variants also increased nuclear shuttling of β-catenin (CTNNB1) and increased the expression of TWIST1, which are inhibitory to chondrogenesis. In canonical WNT luciferase assays using frontonasal mass cells, the variants had dominant-negative effects on wild-type FZD2. In non-canonical assays, the 425C>T variant failed to activate the reporter above control levels and was unresponsive to exogenous WNT5A. This is the first single amino acid change to selectively alter ligand binding in a FZD receptor. Therefore, FZD2 missense variants are pathogenic and could lead to the altered craniofacial morphogenesis seen in Robinow syndrome.

Tooth number abnormality: from bench to bedside

Tooth number abnormality is one of the most common dental developmental diseases, which includes both tooth agenesis and supernumerary teeth. Tooth development is regulated by numerous developmental signals, such as the well-known Wnt, BMP, FGF, Shh and Eda pathways, which mediate the ongoing complex interactions between epithelium and mesenchyme. Abnormal expression of these crutial signalling during this process may eventually lead to the development of anomalies in tooth number; however, the underlying mechanisms remain elusive. In this review, we summarized the major process of tooth development, the latest progress of mechanism studies and newly reported clinical investigations of tooth number abnormality. In addition, potential treatment approaches for tooth number abnormality based on developmental biology are also discussed. This review not only provides a reference for the diagnosis and treatment of tooth number abnormality in clinical practice but also facilitates the translation of basic research to the clinical application.

Genetics of non-isolated hemivertebra: A systematic review of fetal, neonatal, and infant cases

Hemivertebra is a congenital vertebral malformation caused by unilateral failure of formation during embryogenesis that may be associated with additional abnormalities. A systematic review was conducted to investigate genetic etiologies of non-isolated hemivertebra identified in the fetal, neonatal, and infant periods using PubMed, Cochrane database, Ovid Medline, and ClinicalTrials.gov from inception through May 2022 (PROSPERO ID CRD42021229576). The Human Phenotype Ontology database was accessed May 2022. Studies were deemed eligible for inclusion if they addressed non-isolated hemivertebra or genetic causes of non-isolated hemivertebra identified in the fetal, neonatal, or infant periods. Cases diagnosed clinically without molecular confirmation were included. Systematic review identified 23 cases of non-isolated hemivertebra with karyotypic abnormalities, 2 cases due to microdeletions, 59 cases attributed to single gene disorders, 18 syndromic cases without known genetic etiology, and 14 cases without a known syndromic association. The Human Phenotype Ontology search identified 49 genes associated with hemivertebra. Non-isolated hemivertebra is associated with a diverse spectrum of cytogenetic abnormalities and single gene disorders. Genetic syndromes were notably common. Frequently affected organ systems include musculoskeletal, cardiovascular, central nervous system, genitourinary, gastrointestinal, and facial dysmorphisms. When non-isolated hemivertebra is identified on prenatal ultrasound, the fetus must be assessed for associated anomalies and genetic counseling is recommended.

Obstetrical Challenges in Robinow Syndrome

Robinow syndrome is a genetically heterogenous syndrome that exhibits great pleiotropy, involving skeletal genital, cardiac, and craniofacial developmental anomalies. Fertility is not always compromised, and many individuals may be able to have a healthy pregnancy. Similar to other more common skeletal dysplasias and growth disorders such as achondroplasia, there are several challenges to be addressed in managing physiologic differences that occur in the context of pregnancy, and published literature centers on pregnant people with achondroplasia. We present a patient with Robinow syndrome (ROR2 variant), follow her clinical course through three of her pregnancies (one 20-week loss followed by two preterm cesarean deliveries at 36-week gestation), and highlight the major obstetrical considerations in her individualized care.

Phenotypic and mutational spectrum of ROR2-related Robinow syndrome

Robinow syndrome is characterized by a triad of craniofacial dysmorphisms, disproportionate-limb short stature and genital hypoplasia. A significant degree of phenotypic variability seems to correlate with different genes/loci. Disturbances of the non-canonical WNT-pathway have been identified as the main cause of the syndrome. Biallelic variants in ROR2 cause an autosomal recessive form of the syndrome with distinctive skeletal findings. Twenty-two patients with a clinical diagnosis of autosomal recessive Robinow syndrome were screened for variants in ROR2 using multiple molecular approaches. We identified 25 putatively pathogenic ROR2 variants, 16 novel, including single nucleotide variants and exonic deletions. Detailed phenotypic analyses revealed that all subjects presented with a prominent forehead, hypertelorism, short nose, abnormality of the nasal tip, brachydactyly, mesomelic limb shortening, short stature and genital hypoplasia in male patients. A total of 19 clinical features were present in more than 75% of the subjects, thus pointing to an overall uniformity of the phenotype. Disease-causing variants in ROR2, contribute to a clinically recognizable AR trait phenotype with multiple skeletal defects. A comprehensive quantitative clinical evaluation this cohort delineated the phenotypic spectrum of ROR2-related Robinow syndrome. The identification of exonic deletion variant alleles further supports the contention of a loss-of-function mechanism in the etiology of the syndrome. This article is protected by copyright. All rights reserved.

Novel pathogenic variants and quantitative phenotypic analyses of Robinow syndrome: WNT signaling perturbation and phenotypic variability

Robinow syndrome (RS) is a genetically heterogeneous disorder with six genes that converge on the WNT/planar cell polarity (PCP) signaling pathway implicated (DVL1, DVL3, FZD2, NXN, ROR2, and WNT5A). RS is characterized by skeletal dysplasia and distinctive facial and physical characteristics. To further explore the genetic heterogeneity, paralog contribution, and phenotypic variability of RS, we investigated a cohort of 22 individuals clinically diagnosed with RS from 18 unrelated families. Pathogenic or likely pathogenic variants in genes associated with RS or RS phenocopies were identified in all 22 individuals, including the first variant to be reported in DVL2. We retrospectively collected medical records of 16 individuals from this cohort and extracted clinical descriptions from 52 previously published cases. We performed Human Phenotype Ontology (HPO) based quantitative phenotypic analyses to dissect allele-specific phenotypic differences. Individuals with FZD2 variants clustered into two groups with demonstrable phenotypic differences between those with missense and truncating alleles. Probands with biallelic NXN variants clustered together with the majority of probands carrying DVL1, DVL2, and DVL3 variants, demonstrating no phenotypic distinction between the NXN-autosomal recessive and dominant forms of RS. While phenotypically similar diseases on the RS differential matched through HPO analysis, clustering using phenotype similarity score placed RS-associated phenotypes in a unique cluster containing WNT5A, FZD2, and ROR2 apart from non-RS-associated paralogs. Through human phenotype analyses of this RS cohort and OMIM clinical synopses of Mendelian disease, this study begins to tease apart specific biologic roles for non-canonical WNT-pathway proteins.

Intertwined Signaling Pathways Governing Tooth Development: A Give-and-Take Between Canonical Wnt and Shh

Teeth play essential roles in life. Their development relies on reciprocal interactions between the ectoderm-derived dental epithelium and the underlying neural crest-originated mesenchyme. This odontogenic process serves as a prototype model for the development of ectodermal appendages. In the mouse, developing teeth go through distinct morphological phases that are tightly controlled by epithelial signaling centers. Crucial molecular regulators of odontogenesis include the evolutionarily conserved Wnt, BMP, FGF and sonic hedgehog (Shh) pathways. These signaling modules do not act on their own, but are closely intertwined during tooth development, thereby outlining the path to be taken by specific cell populations including the resident dental stem cells. Recently, pivotal Wnt-Shh interaction and feedback loops have been uncovered during odontogenesis, showing conservation in other developing ectodermal appendages. This review provides an integrated overview of the interplay between canonical Wnt and Shh throughout mouse tooth formation stages, extending from the initiation of dental placode to the fully formed adult tooth.

Robinow syndrome in a newborn presenting with hydrocephalus and craniosynostosis

INTRODUCTION

Robinow syndrome is a rare entity with a characteristic appearance, such as hypertelorism, short stature, mesomelic shortening of the limbs, hypoplastic genitalia, and rib as well as vertebral anomalies. We had treated a patient with Robinow syndrome who developed hydrocephalus and craniosynostosis which is not usually associated.

CASE PRESENTATION

The ventricle enlargement was detected during pregnancy in a female infant. She did not develop hydrocephalus just after birth. Her facial appearance was fetus-like, so the pediatricians had suspected Robinow syndrome. During follow-up examinations, a rapidly enlarging head circumference was detected when she was 3 months old. Her conscious level was not disturbed, but she had a tight fontanel and sunset phenomenon was recognized. Hydrocephalus was diagnosed by radiographic imaging so that she underwent ventriculo-peritoneal shunting (VPS). Her irregular head enlargement seized. Six months after surgery, her parents noticed the brachycephalic shape of her head. A computed tomography (CT) and magnetic resonance (MR) scan were conducted and showed that her bilateral coronal, bilateral lambdoid, and the sagittal suture were fused in addition with a tonsillar herniation. Since the sutures were not remaining, we diagnosed that this was a primary pan synostosis rather than secondary craniosynostosis due to VPS. Posterior cranial vault distraction with foramen magnum decompression (FMD) was conducted. The distractor was extended by 1 mm per day up to 30 mm. After a consolidation period of 2 months, the distractors were removed. Through this intervention, a 15.4% increase (+196cc) of the intracranial space with an improvement of the chronic tonsillar herniation was achieved.

CONCLUSION

To confirm the diagnosis of Robinow syndrome, a genetic test was conducted. The analysis showed ROR2 Exon3 (c233 c>t p. Thr 78 Met), which is found in the recessive type of Robinow syndrome. We report this patient as, to our best knowledge, the first case documented case of Robinow disease presenting with hydrocephalus and craniosynostosis. Posterior cranial vault distraction with FMD is a useful way to treat this condition.

Clinical and molecular characterization of four patients with Robinow syndrome from different families

Robinow syndrome (RS) is a rare heterogeneous disorder characterized by short stature, short-limbs, craniofacial, oro-dental abnormalities, vertebral segmentation defects, and frequently genital hypoplasia. Both autosomal dominant and recessive patterns of inheritance are observed with many causative genes. Here, we present the phenotypes and genotypes of four children with RS from different Indian families. Sequence variants were identified in genes ROR2, DVL1, and DVL3. Our results expand the mutational spectrum of RS and we also highlight the radiological changes in the radius and ulna in patients with ROR2 sequence variants which are primarily characteristic for ROR2 related RS but have been reported in WNT5A related RS.

Robinow syndrome: Genital analysis, genetic heterogeneity, and associated psychological impact

Robinow syndrome (RS) is a rare, pleiotropic genetic disorder. While it has been reported that males with Robinow syndrome may have genitourinary atypicalities, these have not been systematically studied. We hypothesized that the underlying gene involved plays a role in the clinical variability of associated genital findings and that the phenotypic appearance of the genitalia in RS may have a psychological impact. Urologic-specific examination consisted of detailed examination and a questionnaire to investigate the psychological impact of the genital phenotype. Nine males agreed to a full evaluation. Average age was 19.9 years, penile length was 32.5 mm, stretched length 53 mm, and width 24.4 mm. Penile transposition occurred in all 9 male who allowed full examination. Undescended testicles were noted in 4/10, testicular atrophy in 5/9, buried penis in 7/9, hypospadias in 5/8, and a large penopubic gap (space between dorsum of penis base and pubic bone) in 5/6. In this cohort, 78% answered our semi-quantitative pilot questionnaire that identified diminished sexuality, sexual function, and self-perception. In conclusion, RS has unique, hallmark genital findings including penile transposition, buried penis, undescended testes, and large penopubic gaps. Genital phenotype in males was not shown to correlate with the specific gene involved for each patient. Surgical approaches and other interventions should be studied to address the findings of decreased sexuality and self-perception. It is the authors' opinion that intervention to provide the appearance of penile lengthening be postponed until puberty to allow for maximal natural phallic growth.

Craniofacial phenotypes associated with Robinow syndrome

Robinow syndrome is characterized by mesomelic limb shortening, hemivertebrae, and genital hypoplasia. Due to low prevalence and considerable phenotypic variability, it has been challenging to definitively characterize features of Robinow syndrome. While craniofacial abnormalities associated with Robinow syndrome have been broadly described, there is a lack of detailed descriptions of genotype-specific phenotypic craniofacial features. Patients with Robinow syndrome were invited for a multidisciplinary evaluation conducted by specialist physicians at our institution. A focused assessment of the craniofacial manifestations was performed by a single expert examiner using clinical examination and standard photographic images. A total of 13 patients with clinical and molecular diagnoses consistent with either dominant Robinow syndrome (DRS) or recessive Robinow syndrome (RRS) were evaluated. On craniofacial examination, gingival hyperplasia was nearly ubiquitous in all patients. Orbital hypertelorism, a short nose with anteverted and flared nares, a triangular mouth with a long philtrum, cleft palate, macrocephaly, and frontal bossing were not observed in all individuals but affected individuals with both DRS and RRS. Other anomalies were more selective in their distribution in this patient cohort. We present a comprehensive analysis of the craniofacial findings in patients with Robinow Syndrome, describing associated morphological features and correlating phenotypic manifestations to underlying genotype in a manner relevant for early recognition and focused evaluation of these patients.

Extremity anomalies associated with Robinow syndrome

Robinow syndrome, a rare genetic disorder, is characterized by skeletal dysplasia with, among other anomalies, extremity and hand anomalies. There is locus heterogeneity and both dominant and recessive inheritance. A detailed description of associated extremity and hand anomalies does not currently exist due to the rarity of this syndrome. This study seeks to document the hand anomalies present in Robinow syndrome to allow for improved rates of timely and accurate diagnosis. A focused assessment of the extremities and stature was performed using clinical examination and standard photographic images. A total of 13 patients with clinical and molecular diagnosis consistent with dominant Robinow syndrome or recessive Robinow syndrome were evaluated. All patients had limb shortening, the most common of which was mesomelia; however, rhizomelia and micromelia were also seen. These findings are relevant to clinical characterization, particularly as Robinow syndrome has classically been defined as a "mesomelic disorder." A total of eight distinct hand anomalies were identified in 12 patients with both autosomal recessive and dominant forms of Robinow syndrome. One patient did not present with any hand differences. The most common hand findings included brachydactyly, broad thumbs, and clinodactyly. A thorough understanding of the breadth of Robinow syndrome-associated extremity and hand anomalies can aid in early patient identification, improving rates of timely diagnosis and allowing for proactive management of sequelae.

Neurocognitive, adaptive, and psychosocial functioning in individuals with Robinow syndrome

It has been estimated that 10-15% of people with Robinow syndrome (RS) show delayed development, but no studies have formally assessed developmental domains. The objective of this study is to provide the first description of cognitive, adaptive, and psychological functioning in RS. Thirteen participants (10 males) aged 4-51 years were seen for neuropsychological screening. Eight had autosomal-dominant RS (DVL1, n = 5; WNT5A, n = 3), four had autosomal-recessive RS (NXN, n = 2; ROR2, n = 2), and one had a mutation on an RS candidate gene (GPC4). Participants completed measures of intellectual, fine-motor, adaptive, executive, and psychological functioning. Findings indicated generally average intellectual functioning and low-average visuomotor skills. Adaptive functioning was average in autosomal-recessive RS (RRS) but low average in autosomal-dominant RS (DRS). Parent-report indicated executive dysfunction and attention problems in 4/8 children, 3/4 of whom had a DVL1 variant; adult self-report did not indicate similar difficulties. Learning disabilities were also reported in 4/8 individuals with DRS, 3/4 of whom had a DVL1 variant. Peer problems were reported for a majority of participants, many of whom also reported emotional concerns. Altogether, the findings indicate average neurocognitive functioning in RRS. In contrast, DRS, especially DVL1 pathogenic alleles, may confer specific risk for neurodevelopmental disability.

Characterization of the Robinow syndrome skeletal phenotype, bone micro-architecture, and genotype-phenotype correlations with the osteosclerotic form

Robinow syndrome (RS) is a genetically heterogeneous skeletal dysplasia with recent reports suggesting an osteosclerotic form of the disease. We endeavored to investigate the full spectrum of skeletal anomalies in a genetically diverse cohort of RS patients with a focus on the bone micro-architecture. Seven individuals with molecularly confirmed RS, including four with DVL1 variants and single individuals with variants in WNT5A, ROR2, and GPC4 underwent a musculoskeletal focused physical examination, dual-energy X-ray absorptiometry (DEXA) scan, and high-resolution peripheral quantitative computed tomography (HR-pQCT). Skeletal examination revealed variability in limb shortening anomalies consistent with recent reports. DEXA scan measures revealed increased total body bone mineral density (BMD) (3/7), cranial BMD (5/7), and non-cranial BMD (1/7). Cranial osteosclerosis was only observed in DVL1-RS (4/4) and GPC4-RS (1/1) subjects and in one case was complicated by choanal atresia, bilateral conductive hearing loss, and cranial nerve III, VI, and VII palsy. HR-pQCT revealed a unique pattern of low cortical BMD, increased trabecular BMD, decreased number of trabeculations, and increased thickness of the trabeculations for the DVL1-RS subjects. The spectrum of skeletal anomalies including the micro-architecture of the bones observed in RS has considerable variability with some osteosclerosis genotype-phenotype correlations more frequent with DVL1 variants.

Genetic Basis of Human Congenital Heart Disease

Congenital heart disease (CHD) is the most common major congenital anomaly with an incidence of ∼1% of live births and is a significant cause of birth defect-related mortality. The genetic mechanisms underlying the development of CHD are complex and remain incompletely understood. Known genetic causes include all classes of genetic variation including chromosomal aneuploidies, copy number variants, and rare and common single-nucleotide variants, which can be either de novo or inherited. Among patients with CHD, ∼8%-12% have a chromosomal abnormality or aneuploidy, between 3% and 25% have a copy number variation, and 3%-5% have a single-gene defect in an established CHD gene with higher likelihood of identifying a genetic cause in patients with nonisolated CHD. These genetic variants disrupt or alter genes that play an important role in normal cardiac development and in some cases have pleiotropic effects on other organs. This work reviews some of the most common genetic causes of CHD as well as what is currently known about the underlying mechanisms.

Tomographic Study of the Malformation Complex in Correlation With the Genotype in Patients With Robinow Syndrome: Review Article

We aimed to understand the etiology behind the abnormal craniofacial contour and other clinical presentations in a number of children with Robinow syndrome. Seven children with Robinow syndrome were enrolled in this study (autosomal recessive caused by homozygous mutations in the ROR2 gene on chromosome 9q22, and the autosomal dominant caused by heterozygous mutation in the WNT5A gene on chromosome 3p14). In the autosomal recessive (AR) group, the main clinical presentations were intellectual, disability, poor schooling achievement, episodes of headache/migraine, and poor fine motor coordinative skills, in addition to massive restrictions of the spine biomechanics causing effectively the development of kyposcoliosis and frequent bouts of respiratory infections. Three-dimensional reconstruction computed tomography scan revealed early closure of the metopic and the squamosal sutures of skull bones. Massive spinal malsegmentation and unsegmented spinal bar were noted in the AR group. In addition to severe mesomelia and camptodactyly, in the autosomal dominant (AD) group, no craniosynostosis but few Wormian bones and the spine showed limited malsegemetation, and no mesomelia or camptodactyly have been noted. We wish to stress that little information is available in the literature regarding the exact pathology of the cranial bones, axial, and appendicular malformations in correlation with the variable clinical presentations in patients with the 2 types of Robinow syndrome.

Robinow syndrome skeletal phenotypes caused by the WNT5AC83S variant are due to dominant interference with chondrogenesis

Heterozygous missense mutations in several genes in the WNT5A signaling pathway cause autosomal dominant Robinow syndrome 1 (DRS1). Our objective was to clarify the functional impact of a missense mutation in WNT5A on the skeleton, one of the main affected tissues in RS. We delivered avian replication competent retroviruses (RCAS) containing human wild-type WNT5A (wtWNT5A), WNT5AC83S variant or GFP/AlkPO4 control genes to the chicken embryo limb. Strikingly, WNT5AC83S consistently caused a delay in ossification and bones were more than 50% shorter and 200% wider than controls. In contrast, bone dimensions in wtWNT5A limbs were slightly affected (20% shorter, 25% wider) but ossification occurred on schedule. The dysmorphology of bones was established during cartilage differentiation. Instead of stereotypical stacking of chondrocytes, the WNT5AC83S-infected cartilage was composed of randomly oriented chondrocytes and that had diffuse, rather than concentrated Prickle staining, both signs of disrupted planar cell polarity (PCP) mechanisms. Biochemical assays revealed that C83S variant was able to activate the Jun N-terminal kinase-PCP pathway similar to wtWNT5A; however, the activity of the variant ligand was influenced by receptor availability. Unexpectedly, the C83S change caused a reduction in the amount of protein being synthesized and secreted, compared to wtWNT5A. Thus, in the chicken and human, RS phenotypes are produced from the C83S mutation, even though the variant protein is less abundant than wtWNT5A. We conclude the variant protein has dominant-negative effects on chondrogenesis leading to limb abnormalities.

From microcephaly to megalencephaly: determinants of brain size

Expansion of the human brain, and specifically the neocortex, is among the most remarkable evolutionary processes that correlates with cognitive, emotional, and social abilities. Cortical expansion is determined through a tightly orchestrated process of neural stem cell proliferation, migration, and ongoing organization, synaptogenesis, and apoptosis. Perturbations of each of these intricate steps can lead to abnormalities of brain size in humans, whether small (microcephaly) or large (megalencephaly). Abnormalities of brain growth can be clinically isolated or occur as part of complex syndromes associated with other neurodevelopmental problems (eg, epilepsy, autism, intellectual disability), brain malformations, and body growth abnormalities. Thorough review of the genetic literature reveals that human microcephaly and megalencephaly are caused by mutations of a rapidly growing number of genes linked within critical cellular pathways that impact early brain development, with important pathomechanistic links to cancer, body growth, and epilepsy. Given the rapid rate of causal gene identification for microcephaly and megalencephaly understanding the roles and interplay of these important signaling pathways is crucial to further unravel the mechanisms underlying brain growth disorders and, more fundamentally, normal brain growth and development in humans. In this review, we will (a) overview the definitions of microcephaly and megalencephaly, highlighting their classifications in clinical practice; (b) overview the most common genes and pathways underlying microcephaly and megalencephaly based on the fundamental cellular processes that are perturbed during cortical development; and (c) outline general clinical molecular diagnostic workflows for children and adults presenting with microcephaly and megalencephaly.

Tracking diphyodont development in miniature pigs in vitro and in vivo

Abnormalities of tooth number in humans, such as agenesis and supernumerary tooth formation, are closely related to diphyodont development. There is an increasing demand to understand the molecular and cellular mechanisms behind diphyodont development through the use of large animal models, since they are the most similar to the mechanism of human tooth development. However, attempting to study diphyodont development in large animals remains challenging due to large tooth size, prolonged growth stage and embryo manipulation. Here, we characterized the expression of possible genes for diphyodont development and odontogenesis of an organoid bud from single cells of tooth germs in vitro using Wzhishan pig strain (WZSP). Following this, we used a method of ectopic transplantation of tooth germs at cap stage to dynamically track diphyodont development of tooth germs in mouse subrenal capsules to overcome the restrictions in pig embryos. The results showed that pig tooth germ at cap stage could restore diphyodont development and maintain efficient long-term survival and growth in mouse subrenal capsules, which is suitable for future manipulation of large mammalian tooth development. Our pilot study provided an alternative for studying diphyodont development in large mammals, which will further promote the use of pig as a diphyodont model similar to humans for craniofacial development study.

Summary: Little is known about diphyodont development in large animals. Our pilot trial characterized this gene expression and developed an alternative method to track diphyodont development in pigs.

Whole genome variant association across 100 dogs identifies a frame shift mutation in DISHEVELLED 2 which contributes to Robinow-like syndrome in Bulldogs and related screw tail dog breeds

Domestic dog breeds exhibit remarkable morphological variations that result from centuries of artificial selection and breeding. Identifying the genetic changes that contribute to these variations could provide critical insights into the molecular basis of tissue and organismal morphogenesis. Bulldogs, French Bulldogs and Boston Terriers share many morphological and disease-predisposition traits, including brachycephalic skull morphology, widely set eyes and short stature. Unlike other brachycephalic dogs, these breeds also exhibit vertebral malformations that result in a truncated, kinked tail (screw tail). Whole genome sequencing of 100 dogs from 21 breeds identified 12.4 million bi-allelic variants that met inclusion criteria. Whole Genome Association of these variants with the breed defining phenotype of screw tail was performed using 10 cases and 84 controls and identified a frameshift mutation in the WNT pathway gene DISHEVELLED 2 (DVL2) (Chr5: 32195043_32195044del, p = 4.37 X 10-37) as the most strongly associated variant in the canine genome. This DVL2 variant was fixed in Bulldogs and French Bulldogs and had a high allele frequency (0.94) in Boston Terriers. The DVL2 variant segregated with thoracic and caudal vertebral column malformations in a recessive manner with incomplete and variable penetrance for thoracic vertebral malformations between different breeds. Importantly, analogous frameshift mutations in the human DVL1 and DVL3 genes cause Robinow syndrome, a congenital disorder characterized by similar craniofacial, limb and vertebral malformations. Analysis of the canine DVL2 variant protein showed that its ability to undergo WNT-induced phosphorylation is reduced, suggesting that altered WNT signaling may contribute to the Robinow-like syndrome in the screwtail breeds.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

Multiple supernumerary teeth in a likely syndromic individual from prehistoric Illinois

OBJECTIVE

This paper reports the first published case of a prehistoric human with five or more supernumerary teeth. Such cases are often neglected in paleopathology, in part due to a gap between the medicodental and anthropological literature leading to the view in anthropology that supernumerary teeth are curious anomalies rather than pathologies.

DESIGN

Reconstruction and pathological description of the skeletal remains were performed according to standard osteological protocols. Each supernumerary tooth was categorized based on its morphology, location, and orientation. The dental characteristics of the individual were compared to published norms for incidences of syndromic and non-syndromic supernumerary teeth and a differential diagnosis was subsequently performed.

RESULTS

Six supernumerary teeth and one deciduous tooth were identified. Additionally, the individual suffered from impacted teeth, dilacerated roots, and extensive sutural anomalies (including retention of the metopic suture into adulthood and an unusually high number of sutural bones). The morphology and location of the supernumerary teeth, in conjunction with the suite of other symptoms, are highly unusual among non-syndromic patients and therefore are indicative of a complex genetic disorder.

CONCLUSIONS

The individual reported here almost certainly suffered from a genetic disorder or syndrome resulting in extensive dental and sutural abnormalities. Despite a lack of post-cranial involvement, a tentative diagnosis of Cleidocranial Dysplasia was made on the basis that mutations in the RUNX2 gene may cause the dental symptoms without any pathology of the clavicle.

WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome

Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, ∼70% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like phenotypes and performed genetic and genomic studies. In total, four families with variants in FZD2 were identified as well as three individuals from two families with biallelic variants in NXN that co-segregate with the phenotype. Importantly, both FZD2 and NXN are relevant protein partners in the WNT5A interactome, supporting their role in skeletal development. In addition to confirming that clustered -1 frameshifting variants in DVL1 and DVL3 are the main contributors to dominant Robinow syndrome, we also found likely pathogenic variants in candidate genes GPC4 and RAC3, both linked to the Wnt signaling pathway. These data support an initial hypothesis that Robinow syndrome results from perturbation of the Wnt/PCP pathway, suggest specific relevant domains of the proteins involved, and reveal key contributors in this signaling cascade during human embryonic development. Contrary to the view that non-allelic genetic heterogeneity hampers gene discovery, this study demonstrates the utility of rare disease genomic studies to parse gene function in human developmental pathways.

Robinow Syndrome and Fusion of Primary Teeth

Managing patients with rare genetic disorders is a challenge that dentists face often. Robinow syndrome (RS) is one such rare genetic disorder with <200 cases reported worldwide. RS demonstrates multiple craniofacial abnormalities and orodental disorders, which need to be taken into consideration by a dental practitioner while rendering dental care.

Dental management and orofacial manifestations of a patient with Robinow Syndrome

Robinow syndrome (RS) is an extremely rare condition. Characteristic craniofacial findings of RS include a fetal facial appearance, ear abnormalities and oral findings. The aim of this case report was to evaluate the oral findings of a 26-year-old man with RS and to describe the dental treatments performed. The patient had short stature, vertebral anomalies, short and broad fingers, a fetal facial appearance, gingival hyperplasia, fissured tongue, caries and multiple impacted teeth. Periodontal and restorative dental treatments were performed under aseptic conditions with due precautions. No surgical treatment was performed to the impacted teeth because of the lack of symptoms.

Molecular genetics and targeted therapy of WNT-related human diseases (Review)

Canonical WNT signaling through Frizzled and LRP5/6 receptors is transduced to the WNT/β-catenin and WNT/stabilization of proteins (STOP) signaling cascades to regulate cell fate and proliferation, whereas non-canonical WNT signaling through Frizzled or ROR receptors is transduced to the WNT/planar cell polarity (PCP), WNT/G protein-coupled receptor (GPCR) and WNT/receptor tyrosine kinase (RTK) signaling cascades to regulate cytoskeletal dynamics and directional cell movement. WNT/β-catenin signaling cascade crosstalks with RTK/SRK and GPCR-cAMP-PKA signaling cascades to regulate β-catenin phosphorylation and β-catenin-dependent transcription. Germline mutations in WNT signaling molecules cause hereditary colorectal cancer, bone diseases, exudative vitreoretinopathy, intellectual disability syndrome and PCP-related diseases. APC or CTNNB1 mutations in colorectal, endometrial and prostate cancers activate the WNT/β-catenin signaling cascade. RNF43, ZNRF3, RSPO2 or RSPO3 alterations in breast, colorectal, gastric, pancreatic and other cancers activate the WNT/β-catenin, WNT/STOP and other WNT signaling cascades. ROR1 upregulation in B-cell leukemia and solid tumors and ROR2 upregulation in melanoma induce invasion, metastasis and therapeutic resistance through Rho-ROCK, Rac-JNK, PI3K-AKT and YAP signaling activation. WNT signaling in cancer, stromal and immune cells dynamically orchestrate immune evasion and antitumor immunity in a cell context-dependent manner. Porcupine (PORCN), RSPO3, WNT2B, FZD5, FZD10, ROR1, tankyrase and β-catenin are targets of anti-WNT signaling therapy, and ETC-159, LGK974, OMP-18R5 (vantictumab), OMP-54F28 (ipafricept), OMP-131R10 (rosmantuzumab), PRI-724 and UC-961 (cirmtuzumab) are in clinical trials for cancer patients. Different classes of anti-WNT signaling therapeutics are necessary for the treatment of APC/CTNNB1-, RNF43/ZNRF3/RSPO2/RSPO3- and ROR1-types of human cancers. By contrast, Dickkopf-related protein 1 (DKK1), SOST and glycogen synthase kinase 3β (GSK3β) are targets of pro-WNT signaling therapy, and anti-DKK1 (BHQ880 and DKN-01) and anti-SOST (blosozumab, BPS804 and romosozumab) monoclonal antibodies are being tested in clinical trials for cancer patients and osteoporotic post-menopausal women. WNT-targeting therapeutics have also been applied as reagents for in vitro stem-cell processing in the field of regenerative medicine.

A novel mutation of adenomatous polyposis coli (APC) gene results in the formation of supernumerary teeth

Supernumerary teeth are teeth that are present in addition to normal teeth. Although several hypotheses and some molecular signalling pathways explain the formation of supernumerary teeth, but their exact disease pathogenesis is unknown. To study the molecular mechanisms of supernumerary tooth‐related syndrome (Gardner syndrome), a deeper understanding of the aetiology of supernumerary teeth and the associated syndrome is needed, with the goal of inhibiting disease inheritance via prenatal diagnosis. We recruited a Chinese family with Gardner syndrome. Haematoxylin and eosin staining of supernumerary teeth and colonic polyp lesion biopsies revealed that these patients exhibited significant pathological characteristics. APC gene mutations were detected by PCR and direct sequencing. We revealed the pathological pathway involved in human supernumerary tooth development and the mouse tooth germ development expression profile by RNA sequencing (RNA‐seq). Sequencing analysis revealed that an APC gene mutation in exon 15, namely 4292‐4293‐Del GA, caused Gardner syndrome in this family. This mutation not only initiated the various manifestations typical of Gardner syndrome but also resulted in odontoma and supernumerary teeth in this case. Furthermore, RNA‐seq analysis of human supernumerary teeth suggests that the APC gene is the key gene involved in the development of supernumerary teeth in humans. The mouse tooth germ development expression profile shows that the APC gene plays an important role in tooth germ development. We identified a new mutation in the APC gene that results in supernumerary teeth in association with Gardner syndrome. This information may shed light on the molecular pathogenesis of supernumerary teeth. Gene‐based diagnosis and gene therapy for supernumerary teeth may become available in the future, and our study provides a high‐resolution reference for treating other syndromes associated with supernumerary teeth.

Genetic analysis of non-syndromic familial multiple supernumerary premolars

OBJECTIVE

Supernumerary teeth, a term describing a condition where patients have an abnormally large number of teeth, can be associated with non-syndromic or syndromic phenotypes. PDGFRs are cell surface tyrosine kinase receptors, and are involved in several aspects of tooth development. The purpose of this study was to identify causative genes of familial supernumerary teeth and the molecular pathogenesis of tooth number abnormalities through genetic analysis of a family that showed supernumerary premolars in two successive generations.

MATERIAL AND METHODS

We recruited a Korean family with supernumerary premolars and performed mutational analyses to identify the underlying molecular genetic aetiology.

RESULTS

Targeted exome sequencing identified a missense mutation in PDGFRB (c.C2053T, p.R685C). Sanger sequencing confirmed that three affected individuals in the patient's family were heterozygous for the mutation.

CONCLUSIONS

This is the first report of a Korean family that carries a PDGFRB mutation potentially responsible for supernumerary premolars. Our results demonstrate the power of next-generation sequencing in rapidly determining the genetic aetiology of numerical tooth abnormalities.

The epidemiology of supernumerary teeth and the associated molecular mechanism

Supernumerary teeth are common clinical dental anomalies. Although various studies have provided abundant information regarding genes and signaling pathways involved in tooth morphogenesis, which include Wnt, FGF, BMP, and Shh, the molecular mechanism of tooth formation, especially for supernumerary teeth, is still unclear. In the population, some cases of supernumerary teeth are sporadic, while others are syndrome-related with familial hereditary. The prompt and accurate diagnosis of syndrome related supernumerary teeth is quite important for some distinctive disorders. Mice are the most commonly used model system for investigating supernumerary teeth. The upregulation of Wnt and Shh signaling in the dental epithelium results in the formation of multiple supernumerary teeth in mice. Understanding the molecular mechanism of supernumerary teeth is also a component of understanding tooth formation in general and provides clinical guidance for early diagnosis and treatment in the future.

Prenatal diagnosis of autosomal recessive Robinow syndrome using 3D ultrasound

This article hypothesizes that it is possible to detect and diagnose both the autosomal recessive and dominant forms prenatally using ultrasound. By focusing on the characteristic phenotypical presentation, the examinator is able to diagnose the syndrome prenatally, which is of clinical importance to the parents and counseling for the consideration of terminating the pregnancy.

Orofacial Manifestations of Autosomal Recessive Robinow's Syndrome: A Rare Case Report

Robinow's syndrome is a very rare genetic disorder which bears a resemblance to a foetal face. It is characterized by short-limbed dwarfism, defects in vertebral segmentation and abnormalities in the head, face and external genitalia. It has a genetic heterogeneity with autosomal dominant and recessive forms which relates to the severity of phenotype presentation. A rare case of an autosomal recessive form of Robinow's syndrome is presented with emphasis on, characteristic craniofacial and intraoral manifestations to aid in diagnosis and dental management of this patient.

DVL3 Alleles Resulting in a -1 Frameshift of the Last Exon Mediate Autosomal-Dominant Robinow Syndrome

Robinow syndrome is a rare congenital disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features. Recent reports have identified, in individuals with dominant Robinow syndrome, a specific type of variant characterized by being uniformly located in the penultimate exon of DVL1 and resulting in a -1 frameshift allele with a premature termination codon that escapes nonsense-mediated decay. Here, we studied a cohort of individuals who had been clinically diagnosed with Robinow syndrome but who had not received a molecular diagnosis from variant studies of DVL1, WNT5A, and ROR2. Because of the uniform location of frameshift variants in DVL1-mediated Robinow syndrome and the functional redundancy of DVL1, DVL2, and DVL3, we elected to pursue direct Sanger sequencing of the penultimate exon of DVL1 and its paralogs DVL2 and DVL3 to search for potential disease-associated variants. Remarkably, targeted sequencing identified five unrelated individuals harboring heterozygous, de novo frameshift variants in DVL3, including two splice acceptor mutations and three 1 bp deletions. Similar to the variants observed in DVL1-mediated Robinow syndrome, all variants in DVL3 result in a -1 frameshift, indicating that these highly specific alterations might be a common cause of dominant Robinow syndrome. Here, we review the current knowledge of these peculiar variant alleles in DVL1- and DVL3-mediated Robinow syndrome and further elucidate the phenotypic features present in subjects with DVL1 and DVL3 frameshift mutations.

Robinow Syndrome: A Rare Diagnosis

Robinow syndrome is a rare entity characterized by short stature and abnormalities of the head, face and external genitalia. It is otherwise called 'fetal face syndrome' due to its resemblance with fetal face. We present an eight-year-old female child who came with mesomelic short stature, abnormal facial features, multiple sets of teeth (both deciduous and permanent), pectus excavatum, umbilical hernia, limb abnormalities like shortening of fore arm, simian crease, broad thumbs and other fingers, clinodactyly, abnormal carrying angle, absent labia minora, absent clitoris. Apart from physical appearance she was having diversification of recti and umbilical hernia. Due to the several physical presentation mild systemic involvement it was diagnosed as autosomal dominant robinow syndrome. She is now on follow up and planned for a cosmetic surgery to repair facial defects.

Clinical and molecular characterization of seven Egyptian families with autosomal recessive robinow syndrome: Identification of four novel ROR2 gene mutations

Robinow syndrome (RS) is a rare genetic disorder characterized by limb shortening, genital hypoplasia, and craniofacial/orodental abnormalities. The syndrome follows both autosomal dominant and recessive patterns of inheritance with similar phenotypic presentation and overlapping features. Autosomal recessive Robinow syndrome (ARRS) is caused by mutations in the ROR2 gene. Here, we present the clinical, radiological and molecular findings of 11 Egyptian patients from 7 unrelated consanguineous families with clinical features of ARRS. Mutation analyses of ROR2 gene identified five pathogenic mutations distributed all over the gene. The identified mutations included four novel (G326A, D166H, S677F, and R528Q) and one previously reported (Y192D). Our results extend the number of ROR2 mutations identified so far, suggest a founder effect in the Egyptian population, and emphasize the important role of genetic testing in proper counseling and patients' management.

Robinow Syndrome: A Rare Case Report and Review of Literature

Robinow syndrome is an extremely rare genetic disorder. Short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral defects comprise its distinct features. This disorder exists in dominant and recessive patterns. Patients with the dominant pattern exhibit moderate symptoms. More physical characteristics and skeletal abnormalities characterize the recessive group. The syndrome is also known as Robinow-Silverman-Smith syndrome, Robinow dwarfism, fetal face, fetal face syndrome, fetal facies syndrome, acral dysostosis with facial and genital abnormalities, or mesomelic dwarfism-small genitalia syndrome. Covesdem syndrome was the name entitled for the recessive form previously. Here, we report a case of 8-year-old female with a autosomal recessive Robinow syndrome having skeletal and vertebral defects. How to cite this article: Soman C, Lingappa A. Robinow Syndrome: A Rare Case Report and Review of Literature. Int J Clin Pediatr Dent 2015;8(2):149-152.

Mutations in DVL1 cause an osteosclerotic form of Robinow syndrome

Robinow syndrome (RS) is a phenotypically and genetically heterogeneous condition that can be caused by mutations in genes encoding components of the non-canonical Wnt signaling pathway. In contrast, germline mutations that act to increase canonical Wnt signaling lead to distinctive osteosclerotic phenotypes. Here, we identified de novo frameshift mutations in DVL1, a mediator of both canonical and non-canonical Wnt signaling, as the cause of RS-OS, an RS subtype involving osteosclerosis, in three unrelated individuals. The mutations all delete the DVL1 C terminus and replace it, in each instance, with a novel, highly basic sequence. We showed the presence of mutant transcript in fibroblasts from one individual with RS-OS and demonstrated unimpaired protein stability with transfected GFP-tagged constructs bearing a frameshift mutation. In vitro TOPFlash assays, in apparent contradiction to the osteosclerotic phenotype, revealed that the mutant allele was less active than the wild-type allele in the canonical Wnt signaling pathway. However, when the mutant and wild-type alleles were co-expressed, canonical Wnt activity was 2-fold higher than that in the wild-type construct alone. This work establishes that DVL1 mutations cause a specific RS subtype, RS-OS, and that the osteosclerosis associated with this subtype might be the result of an interaction between the wild-type and mutant alleles and thus lead to elevated canonical Wnt signaling.

DVL1 frameshift mutations clustering in the penultimate exon cause autosomal-dominant Robinow syndrome

Robinow syndrome is a genetically heterogeneous disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features and for which both autosomal-recessive and autosomal-dominant inheritance patterns have been described. Causative variants in the non-canonical signaling gene WNT5A underlie a subset of autosomal-dominant Robinow syndrome (DRS) cases, but most individuals with DRS remain without a molecular diagnosis. We performed whole-exome sequencing in four unrelated DRS-affected individuals without coding mutations in WNT5A and found heterozygous DVL1 exon 14 mutations in three of them. Targeted Sanger sequencing in additional subjects with DRS uncovered DVL1 exon 14 mutations in five individuals, including a pair of monozygotic twins. In total, six distinct frameshift mutations were found in eight subjects, and all were heterozygous truncating variants within the penultimate exon of DVL1. In five families in which samples from unaffected parents were available, the variants were demonstrated to represent de novo mutations. All variant alleles are predicted to result in a premature termination codon within the last exon, escape nonsense-mediated decay (NMD), and most likely generate a C-terminally truncated protein with a distinct -1 reading-frame terminus. Study of the transcripts extracted from affected subjects' leukocytes confirmed expression of both wild-type and variant alleles, supporting the hypothesis that mutant mRNA escapes NMD. Genomic variants identified in our study suggest that truncation of the C-terminal domain of DVL1, a protein hypothesized to have a downstream role in the Wnt-5a non-canonical pathway, is a common cause of DRS.

Variable expression pattern in Donnai-Barrow syndrome: Report of two novel LRP2 mutations and review of the literature

Donnai-Barrow syndrome (DBS; MIM 222448) is characterized by typical craniofacial anomalies (major hypertelorism with bulging eyes), high grade myopia, deafness and low molecular weight proteinuria. The disorder results from mutations in the low density lipoprotein receptor-related protein 2 gene LRP2 that maps to chromosome 2q31.1. LRP2 encodes megalin, a multi-ligand endocytic receptor. Herein, we describe the clinical presentation of 4 patients from 2 unrelated Saudi families. Two novel LRP2 mutations, a homozygous nonsense mutation (c.4968C>G; p.Tyr1656*) and a missense mutation (c.12062G>A; p.Cys4021Tyr), were detected in the first and second family respectively. Interestingly, intrafamilial phenotypic variability was observed in one family, while DBS features were atypical in the second family. Differential diagnosis of DBS includes several syndromes associating hypertelorism with high grade myopia, and several syndromal forms of CDH, which are briefly summarized in this study.

Odontomas and supernumerary teeth: is there a common origin?

The aim of the present work is to analyze all scientific evidence to verify whether similarities supporting a unified explanation for odontomas and supernumerary teeth exist. A literature search was first conducted for epidemiologic studies indexed by PubMed, to verify their worldwide incidence. The analysis of the literature data shows some interesting similarities between odontomas and supernumerary teeth concerning their topographic distribution and pathologic manifestations. There is also some indication of common genetic and immuno-histochemical factors. Although from a nosological point of view, odontomas and supernumeraries are classified as distinct entities, they seem to be the expression of the same pathologic process, either malformative or hamartomatous.

An osteosclerotic form of Robinow syndrome

Robinow syndrome (RS) is a clinically and genetically heterogenous condition primarily characterized by short stature, mesomelia, genital hypoplasia, oral abnormalities, and a facial gestalt that includes hypertelorism, a short nose, and a broad mouth. The disorder exists in both a dominant and a more severe recessive form. Here two unrelated cases of sporadic RS are described with the additional finding of axial and appendicular osteosclerosis. These two patients, coupled with three additional patients previously described in the literature, may represent a distinct sub-phenotype of this condition.

Prenatal diagnosis of Robinow syndrome: a case report

Robinow syndrome, also known as fetal face syndrome, is a rare genetically heterogeneous condition characterized mainly by mesomelic limb shortening, facial malformations, and genital abnormalities. This report describes the sonographic findings in a case of autosomal-dominant Robinow syndrome diagnosed at 23.1 weeks' gestation, in a patient with no history of affected relatives. Here we describe the sonographic characteristics of this syndrome from the diagnosis until birth. The prenatal and postnatal findings, the differential diagnosis, and the prognosis of patients with this syndrome are discussed. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound, 42:297-300, 2014.

Identification of novel ROR2 gene mutations in Indian children with Robinow syndrome

OBJECTIVE

Robinow syndrome (RS) is an extremely rare genetic disorder characterized by short-limbed dwarfism, defects in vertebral segmentation and abnormalities in the head, face and external genitalia. Mutations in the ROR2 gene cause autosomal recessive RS (RRS) whereas mutations in WNT5A are responsible for the autosomal dominant (AD) form of RS. In AD Robinow patients, oral manifestations are more prominent, while hemivertebrae and scoliosis rarely occur and facial abnormalities tend to be milder.

METHODS

Three unrelated patients from different parts of India were studied. These patients were diagnosed as RRS due to presence of characteristic fetal facies, mesomelia, short stature, micropenis, hemivertebrae and rib abnormalities. One of the patients had fetal facies and micropenis but unusually mild skeletal features. This patient's mother had mild affection in the form of short stature and prominent eyes. Testosterone response to human chorionic gonadotropin was investigated in two patients and were normal. The exons and exon-intron boundaries of the ROR2 gene were sequenced for all probands. Bioinformatics analysis was done for putative variants using SIFT, PolyPhen2 and Mutation Taster.

RESULTS

Patients 1, 2 and 3 were homozygous for c.G545A or p.C182Y in exon 5, c.227G>A or p.G76D in exon 3 and c.668G>A or p.C223Y in exon 6 respectively. Prenatal diagnosis could be performed in an ongoing pregnancy in one family and the fetus was confirmed to be unaffected.

CONCLUSION

ROR2 mutations were documented for the first time in the Indian population. Knowledge of the molecular basis of the disorder served to provide accurate counseling and prenatal diagnosis to the families.

The regulation of testicular descent and the effects of cryptorchidism

The first half of this review examines the boundary between endocrinology and embryonic development, with the aim of highlighting the way hormones and signaling systems regulate the complex morphological changes to enable the intra-abdominal fetal testes to reach the scrotum. The genitoinguinal ligament, or gubernaculum, first enlarges to hold the testis near the groin, and then it develops limb-bud-like properties and migrates across the pubic region to reach the scrotum. Recent advances show key roles for insulin-like hormone 3 in the first step, with androgen and the genitofemoral nerve involved in the second step. The mammary line may also be involved in initiating the migration. The key events in early postnatal germ cell development are then reviewed because there is mounting evidence for this to be crucial in preventing infertility and malignancy later in life. We review the recent advances in what is known about the etiology of cryptorchidism and summarize the syndromes where a specific molecular cause has been found. Finally, we cover the recent literature on timing of surgery, the issues around acquired cryptorchidism, and the limited role of hormone therapy. We conclude with some observations about the differences between animal models and baby boys with cryptorchidism.

Wnt signalling in testicular descent: a candidate mechanism for cryptorchidism in Robinow syndrome

BACKGROUND/AIMS

Robinow syndrome is caused by mutations in Wnt-5a or its receptor Ror2 and can lead to cryptorchidism, though the mechanisms are unclear. Wnt-5a knock-out mice fail to undergo gubernacular swelling, similar to insulin-like hormone 3 (INSl-3) knock-out mice. We aimed to characterise Wnt-5a and Ror2 expression in rat gubernacula to better understand how Wnt-5a signalling affects testicular descent.

METHODS

Sprague-Dawley rats (n = 27) were collected with ethics approval (A644) at embryonic days (E) 15, 17, 19 and postnatal day (D) 2. Control and antiandrogen-treated groups were processed for immunohistochemistry for Wnt-5a, Ror2 and β-catenin. Sagittal sections were examined using confocal microscopy.

RESULTS

Wnt-5a and Ror2 were strongly expressed in the gubernacular bulb at E17 controls, their levels declining at E19 and almost absent by D2. Wnt-5a significantly co-localised with the important transcription factor β-catenin at E17. There was no obvious difference in staining with androgen blockade.

CONCLUSION

Wnt-5a, through Ror2 and β-catenin may play a vital role in regulating the gubernacular swelling reaction downstream of INSL-3. Human mutations in Wnt-5a or Ror2 could prevent early gubernacular growth, as suggested by undescended testes in 70% of patients with Robinow Syndrome.