Phenotypic overlap of McKusick-Kaufman syndrome with Bardet-Biedl syndrome: A literature review

Prenatal hydrocolpos: imaging findings and differential diagnosis

Prenatal hydrocolpos is characterized by fluid distension of the vagina. Hydrocolpos can be caused by multiple underlying etiologies and often demonstrates overlapping imaging features compared to other cystic abdominal and pelvic lesions. The purpose of the current pictorial essay is to provide a systematic prenatal magnetic resonance imaging (MRI) approach to differentiating the primary etiologies leading to hydrocolpos. After discussing the fundamental embryological processes involved in vaginal development, the current essay discusses the most common causes of hydrocolpos with their associated prenatal and postnatal imaging features. An approach to distinguishing the more common differential diagnoses is provided. Given the implications of parental counseling and postnatal management, this essay provides an important approach for narrowing differential diagnoses based on prenatal imaging.

Persistent Urogenital Sinus Leading to Hydrometrocolpos in a Female Child With Features of McKusick-Kaufman Syndrome

Persistent urogenital sinus (PUGS) presents as a solitary abnormality or is in association with syndromes, such as congenital adrenal hyperplasia (CAH), VACTERL association (common abbreviation for vertebral defects, anal atresia, cardiac defects, tracheoesophageal fistula, renal anomalies, and limb abnormalities), Bardet-Beidl syndrome, McKusick-Kaufman syndrome (MKS), and Townes-Brocks syndrome, to name a few. Those affected usually have overlapping phenotypic features of two or more syndromes. Because such children may grow up to be intellectually challenged with multiple other anomalies including gonadal hyperplasia, congenital heart defects, and sensorineural hearing loss, antenatal diagnosis becomes important. Moreover, those who survive into childhood may need a holistic approach to improve their quality of life. This is a rare case of an eight-year-old female child who is a postnatally diagnosed case of congenital heart disease, urogenital sinus with polydactyly, and bilateral hydroureteronephrosis at birth and who is now showing features of multiple overlapping syndromes.

Hydrometrocolpos: antenatal diagnosis and postnatal management

Hydrometrocolpos is a rare finding in newborns. It can be an isolated finding or may be associated with syndromes. Antenatal diagnosis is possible. It is due to the accumulation of secretion in the uterus, distending it and resulting in abdominal swelling. In case of suspected syndromes, an attempt should be made to look for other organ involvement and genetic diagnosis. We here report a term neonate with hydrometrocolpos, which was antenatally diagnosed and was managed conservatively.

McKusick-Kaufman Syndrome: A Case Report With an Emphasis on Perinatal Diagnosis and Genetic Counseling

McKusick-Kaufman syndrome is a rare genetic disorder that affects limb development, genital formation, and heart function. It is caused by mutations in the MKKS gene on chromosome 20. Individuals with this condition may have extra fingers or toes, fused labia or undescended testes, and, less commonly, severe heart defects. Diagnosis involves a physical examination and genetic testing, while treatment focuses on symptom management, including surgical intervention if necessary. The prognosis varies depending on the severity of associated complications. In a recent case, a 27-year-old woman with fetal hydrometrocolpos gave birth to a female neonate with extra digits on both hands and feet, fused labia, and a small vaginal opening. The neonate also had a large abdominal cystic mass, and echocardiography revealed a patent foramen ovale. Genetic testing confirmed an MKKS gene mutation, and the hydrometrocolpos required surgical management. Early diagnosis and intervention can improve outcomes for individuals with this syndrome.

Atypical phenotype of a patient with Bardet-Biedl syndrome type 4

Background

Bardet–Biedl syndrome (BBS) is a multisystemic disorder characterized by rod–cone dystrophy, truncal obesity, postaxial polydactyly, cognitive impairment, male hypogonadotropic hypogonadism, complex female genitourinary malformations, and renal abnormalities. There is a large clinical and also genetic heterogeneity in BBS. Here, we report a patient with polydactyly, hyperechogenic kidneys increased in size with normal corticomedullary differentiation, anal imperforation, and malformation of genitals with presence of a genital tubercle with ventral urethral meatus associated with two unfused lateral genital swelling and absent urethral folds, in the context of 46, XY karyotype.

Methods

Karyotype and solo exome sequencing were performed to look for a genetic etiology for the features described in our patient.

Results

We identified a homozygous in‐frame deletion of exons 4 to 6 in the BBS4 gene (NM‐033028 (BBS4‐i001): c.[(157‐?)_(405 +?)del] p.(Ala53‐Trp135del), which is classified as pathogenic variant. This analysis allowed the molecular diagnosis of BBS type 4 in this patient.

Conclusion

Complex genital malformations are only reported in female BBS6 patients yet, and genital abnormalities and anal imperforation are not reported in male BBS4 patients to date. We discuss the possible hypotheses for this phenotype, including the phenotypic overlap between ciliopathies.

Hydrometrocolpos and postaxial polydactyly in a girl newborn: A case report

This case report is of a 35‐week female neonate with a cystic abdominal mass. Physical examination was notable for post‐axial polydactyly, distended abdomen, and abnormal urethral opening. Differential diagnosis includes Bardet–Biedl Syndrome (BBS), an autosomal recessive ciliopathy. Genetic panel revealed she was a carrier for a BBS mutation.

Hydrometrocolpos in Infants: Etiologies and Clinical Presentations

Hydrometrocolpos (HMC) is a rare condition where fluids or secretions accumulate in the vagina (hydrocolpos) or up to the uterus (hydrometrocolpos). This case series study reports three infants with different etiologies and presentations of HMC and aims to review literature for proper workup upon initial diagnosis. The first neonate antenatally presented with a huge cystic mass. HMC secondary to imperforate hymen was proved, and hymenotomy was performed at 2 days of age. The second participant presented with persistent urogenital sinus and hematopoietic chimerism, possibly due to transfusion from her twin brother via placenta anastomoses. At 2 months of corrected age, she had difficult defecating, and sonogram revealed HMC with normal appearance of uterus and ovaries. Regular follow-ups and surgical reconstruction will be conducted before puberty. The third patient had cloacal malformation and multiple congenital anomalies at birth. Vesicovaginal fistula-related HMC was detected and managed with surgical drainage in the neonate stage. The girl began menstruation with dysmenorrhea at 12 years. The image studies demonstrated hematometrocolpos secondary to left-side hemivaginal septum, uterine didelphy, and ipsilateral renal agenesis, indicating Herlyn–Werner–Wunderlich syndrome. HMC can be diagnosed easily via sonogram. Careful external genitalia examinations help to identify persistent urogenital sinus or cloacal malformation. Occasionally, the HMC may be part of syndrome manifestations or associated with sex chromosome anomalies. Clinicians may conduct surveillance of renal, cardiac, and skeletal systems as well as chromosome study for early diagnosis and management.

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

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

Fetal ciliopathies: a retrospective observational single-center study

Purpose

Report on the diagnosis of prenatally suspected multisystem ciliopathies in a single center between 2002 and 2020.

Methods

Retrospective observational single-center study including pregnancies with prenatal ultrasound features of multisystem ciliopathies, such as hyperechogenic kidneys together with polydactyly and/or other skeletal and extraskeletal findings. Cases were compared according to their prenatal findings and outcomes.

Results

36 cases of multisystem ciliopathies were diagnosed. Meckel-Gruber syndrome (MKS) was the most common ciliopathy (n = 19/36, 52.8%), followed by disorders that belong to the group of short-rib thoracic dysplasia (SRTD, n = 10/36, 27.8%) McKusick–Kaufmann syndrome (MKKS, n = 4/36, 11.1%), Bardet–Biedl syndrome (BBS, n = 2/36, 5.5%) and Joubert syndrome (n = 1/36, 2.8%). All cases showed abnormalities of the kidneys, most often hyperechogenic parenchyma (n = 26/36, 72.2%), cystic dysplasia (n = 24/36, 66.7%), and/or bilateral kidney enlargement (n = 22/36, 61.1%). Oligohydramnios was mainly present in fetuses with MKS. Polydactyly (n = 18/36), abnormalities of the CNS (n = 25/36), and heart defects (n = 10/36) were associated in 50%, 69.4%, and 27.8%, respectively.

Conclusion

Prenatal detection of renal abnormalities associated with skeletal or brain abnormalities should raise the suspicion for multisystem ciliopathies. Prenatal ultrasound can help to differentiate between different diseases and pave the way for subsequent targeted genetic testing.

Gene therapy rescues olfactory perception in a clinically relevant ciliopathy model of Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS) is a hereditary genetic disorder that results in numerous clinical manifestations including olfactory dysfunction. Of at least 21 BBS-related genes that can carry multiple mutations, a pathogenic mutation, BBS1M390R, is the single most common mutation of clinically diagnosed BBS outcomes. While the deletion of BBS-related genes in mice can cause variable penetrance in different organ systems, the impact of the Bbs1M390R mutation in the olfactory system remains unclear. Using a clinically relevant knock-in mouse model homozygous for Bbs1M390R, we investigated the impact of the mutation on the olfactory system and tested the potential of viral-mediated, wildtype gene replacement therapy to rescue smell loss. The cilia of olfactory sensory neurons (OSNs) in Bbs1^M390R/M390R mice were significantly shorter and fewer than those of wild-type mice. Also, both peripheral cellular odor detection and synaptic-dependent activity in the olfactory bulb were significantly decreased in the mutant mice. Furthermore, to gain insight into the degree to which perceptual features are impaired in the mutant mice, we used whole-body plethysmography to quantitatively measure odor-evoked sniffing. The Bbs1^M390R/M390R mice showed significantly higher odor detection thresholds (reduced odor sensitivity) compared to wild-type mice; however, their odor discrimination acuity was still well maintained. Importantly, adenoviral expression of Bbs1 in OSNs restored cilia length and re-established both peripheral odorant detection and odor perception. Together, our findings further expand our understanding for the development of gene therapeutic treatment for congenital ciliopathies in the olfactory system.

Apparent but unconfirmed digenism in an Iranian consanguineous family with syndromic Retinal Disease

BACKGROUND

Bardet-Biedl syndrome is an autosomal recessive disease characterized by rod-cone dystrophy, postaxial polydactyly, kidney defects, obesity, mental retardation and hypogonadism. Here, we report different genotypes in two Bardet-Biedl syndrome affected sisters with a different clinical phenotype regarding severity.

MATERIALS AND METHODS

The proband of the family was examined by Next Generation Sequencing (NGS) using clinical exome and filtering by syndromic and non-syndromic genes associated with retinal dystrophies.

RESULTS

Targeted NGS revealed two novel variants in the MKKS and CEP290 genes in homozygosis state in the proband. Segregation analysis revealed the presence of the same MKKS homozygous variant in her younger affected sister but not the CEP290 variant. Both sisters presented different clinical manifestation, at different ages, with a more severe renal and retinal defect in the case of the sister carrying mutations in both genes. Another unaffected sister showed only homozygosity for the CEP290 variant, thus supporting the non-pathogenic role of this mutation in BBS phenotype.

CONCLUSIONS

In this study, NGS proved to be a powerful and efficient sequencing method to identify causal variants in different genes. However, it remarks the importance of the segregation analysis and clinical information to establish the pathogenicity of new variants. The two affected sisters present different genotypes and clinical manifestation, suggesting that the novel CEP290 variant could be acting as a modifier, making the phenotype more severe in the sister homozygote for MKKS and CEP290 genes. On the other hand, the difference in the age of both sisters highlight the important role of monitoring disease progression also to confirm the modifier role of genetic variants.

The entangled relationship between cilia and actin

Primary cilia are microtubule-based sensory cell organelles that are vital for tissue and organ development. They act as an antenna, receiving and transducing signals, enabling communication between cells. Defects in ciliogenesis result in severe genetic disorders collectively termed ciliopathies. In recent years, the importance of the direct and indirect involvement of actin regulators in ciliogenesis came into focus as it was shown that F-actin polymerisation impacts ciliation. The ciliary basal body was further identified as both a microtubule and actin organising centre. In the current review, we summarize recent studies on F-actin in and around primary cilia, focusing on different actin regulators and their effect on ciliogenesis, from the initial steps of basal body positioning and regulation of ciliary assembly and disassembly. Since primary cilia are also involved in several intracellular signalling pathways such as planar cell polarity (PCP), subsequently affecting actin rearrangements, the multiple effectors of this pathway are highlighted in more detail with a focus on the feedback loops connecting actin networks and cilia proteins. Finally, we elucidate the role of actin regulators in the development of ciliopathy symptoms and cancer.

Clinical and exome sequencing findings in seven children with Bardet-Biedl syndrome from Turkey

BACKGROUND

Bardet-Biedl syndrome (BBS) is a very-rare autosomal recessive genetic disorder with severe multisystem manifestations. Genetic testing plays an important role in the early diagnosis of the disease. In this study, while trying to elucidate the genetic etiology of seven individuals with clinical BBS diagnosis from six different families, we also aimed to examine the distribution of BBS variations in this region of Turkey.

METHODS AND MATERIALS

Exome sequencing analysis is performed for clinically diagnosed patients with BBS in the present study followed by parental segregation. The unreported and previously described clinical features are presented.

RESULTS

Homozygous variants, four of which are unreported, in BBS-related genes (BBS5 [c.682-2A > G], MKKS [c.775del], BBS7 [c.849+1G > T], BBS9 [c.965G > A], BBS10 [c.145C > T], LZTFL1[c.384G > A]) are detected for all the seven individuals included in the study. The most common clinical finding is polydactyly followed by renal anomalies. The clinical features not previously described are correlated to the unreported variant.

CONCLUSIONS

In this study, exome sequencing findings are discussed and four previously unreported disease-associated variants are described including the fifth BBS-implicated LZTFL1 change and possible genotype-phenotype correlation is described.

Genetics of atrioventricular canal defects

Atrioventricular canal defect (AVCD) represents a quite common congenital heart defect (CHD) accounting for 7.4% of all cardiac malformations. AVCD is a very heterogeneous malformation that can occur as a phenotypical cardiac aspect in the context of different genetic syndromes but also as an isolated, non-syndromic cardiac defect. AVCD has also been described in several pedigrees suggesting a pattern of familiar recurrence. Targeted Next Generation Sequencing (NGS) techniques are proved to be a powerful tool to establish the molecular heterogeneity of AVCD.

Given the complexity of cardiac embryology, it is not surprising that multiple genes deeply implicated in cardiogenesis have been described mutated in patients with AVCD. This review attempts to examine the recent advances in understanding the molecular basis of this complex CHD in the setting of genetic syndromes or in non-syndromic patients.

Novel mutation in MKKS/BBS6 linked with arRP and polydactyly in a family of North Indian origin

BACKGROUND

To identify the underlying genetic defect in a fourth-generation autosomal recessive retinitis pigmentosa (arRP) family. Detailed family history and clinical data were collected from nine members, including three affected, from an arRP family.

METHODS

Whole-exome sequencing (WES) was performed on DNA sample of an affected individual IV: 2. Variants obtained by WES were annotated using Ion Reporter Software (ver. 5.2). Potential pathogenic variants detected in an affected member were validated in other affected and unaffected family members by Sanger sequencing. Further 150 ethnically-matched controls were tested for the variant that co-segregated completely with disease in the family, so as to exclude it as a polymorphism. Various web-based bioinformatics tools were also applied to access pathogenic potential of the observed variant.

RESULTS

All the three patients had RP with polydactyly of both hands and feet, however, they did not show other symptoms of Bardet-Biedl syndrome (BBS) or McKusick-Kaufmann Syndrome (MKKS). A novel missense mutation, that is, c.518A>C (p.His173Pro) was identified in MKKS/BBS6 that co-segregated completely with the disease phenotype in all the three affected members and was not observed in six unaffected members of the family. Also the c.518A>C change was not observed in 150 ethnically matched controls (300 chromosomes), hence excluding it as a polymorphism.

CONCLUSIONS

Present study is the second report of identifying a novel mutation in MKKS/BBS6 that is linked with arRP in association with polydactyly, however, with no other signs of BBS or MKKS. These findings further expand the mutation spectrum of MKKS/BBS6 for arRP with polydactyly.

Osteoarthritis-Like Changes in Bardet-Biedl Syndrome Mutant Ciliopathy Mice (Bbs1M390R/M390R): Evidence for a Role of Primary Cilia in Cartilage Homeostasis and Regulation of Inflammation

Osteoarthritis (OA) is a debilitating inflammation related disease characterized by joint pain and effusion, loss of mobility, and deformity that may result in functional joint failure and significant impact on quality of life. Once thought of as a simple “wear and tear” disease, it is now widely recognized that OA has a considerable metabolic component and is related to chronic inflammation. Defects associated with primary cilia have been shown to be cause OA-like changes in Bardet–Biedl mice. We examined the role of dysfunctional primary cilia in OA in mice through the regulation of the previously identified degradative and pro-inflammatory molecular pathways common to OA. We observed an increase in the presence of pro-inflammatory markers TGFβ-1 and HTRA1 as well as cartilage destructive protease MMP-13 but a decrease in DDR-2. We observed a morphological difference in cartilage thickness in Bbs1^M390R/M390R mice compared to wild type (WT). We did not observe any difference in OARSI or Mankin scores between WT and Bbs1^M390R/M390R mice. Primary cilia appear to be involved in the upregulation of biomarkers, including pro-inflammatory markers common to OA.

Prenatal diagnosis of Bardet-Biedl syndrome in a case of hyperechogenic kidneys: Clinical use of DNA sequencing

Bardet–Biedl syndrome (BBS) is a ciliopathy that is responsible for multiple visceral abnormalities. This disorder is defined by a combination of clinical signs, many of which appear after several years of development. BBS may be suspected antenatally based on routine ultrasound findings of enlarged hyperechogenic kidneys and postaxial polydactyly.

Recurrent Urinary Tract Infections in a Female Child With Polydactyly and a Pelvic Mass: Consider the McKusick-Kaufman Syndrome

A 3-year-old female child presented with a history of recurrent urinary tract infections. On general examination, polydactyly and a pelvic mass were present. An imperforate hymen was also documented on vaginal inspection. Further inquiry revealed a positive history of parental consanguinity. A magnetic resonance imaging study defined a hydrometrocolpos responsible for an obstructive cause of the recurrent urinary tract infections. In view of the above, a diagnosis of McKusick-Kaufman syndrome was made. Formal surgical repair of the imperforate hymen with hydrometrocolpos drainage resulted in complete symptom resolution. McKusick-Kaufman syndrome, its presentation, symptoms, differential diagnosis, and underlying genetics were further expanded.

Cilia gene mutations cause atrioventricular septal defects by multiple mechanisms

Atrioventricular septal defects (AVSDs) are a common severe form of congenital heart disease (CHD). In this study we identified deleterious non-synonymous mutations in two cilia genes, Dnah11 and Mks1, in independent N-ethyl-N-nitrosourea-induced mouse mutant lines with heritable recessive AVSDs by whole-exome sequencing. Cilia are required for left/right body axis determination and second heart field (SHF) Hedgehog (Hh) signaling, and we find that cilia mutations affect these requirements differentially. Dnah11^avc4 did not disrupt SHF Hh signaling and caused AVSDs only concurrently with heterotaxy, a left/right axis abnormality. In contrast, Mks1^avc6 disrupted SHF Hh signaling and caused AVSDs without heterotaxy. We performed unbiased whole-genome SHF transcriptional profiling and found that cilia motility genes were not expressed in the SHF whereas cilia structural and signaling genes were highly expressed. SHF cilia gene expression predicted the phenotypic concordance between AVSDs and heterotaxy in mice and humans with cilia gene mutations. A two-step model of cilia action accurately predicted the AVSD/heterotaxyu phenotypic expression pattern caused by cilia gene mutations. We speculate that cilia gene mutations contribute to both syndromic and non-syndromic AVSDs in humans and provide a model that predicts the phenotypic consequences of specific cilia gene mutations.

Bardet-Biedl syndrome with urogenital sinus presenting with acute renal failure in a neonate

This is a case report of Bardet-Biedl syndrome with a urogenital sinus and an ectopic right ureter presenting with acute renal failure in the neonatal period in a female baby. Acute renal failure in these patients is commonly known to occur around 5-7 y of age and neonatal presentation is extremely rare.

Cilia and coordination of signaling networks during heart development

Primary cilia are unique sensory organelles that coordinate a wide variety of different signaling pathways to control cellular processes during development and in tissue homeostasis. Defects in function or assembly of these antenna-like structures are therefore associated with a broad range of developmental disorders and diseases called ciliopathies. Recent studies have indicated a major role of different populations of cilia, including nodal and cardiac primary cilia, in coordinating heart development, and defects in these cilia are associated with congenital heart disease. Here, we present an overview of the role of nodal and cardiac primary cilia in heart development.

Mesoaxial polydactyly is a major feature in Bardet-Biedl syndrome patients with LZTFL1 (BBS17) mutations

Ciliopathies are heterogeneous disorders sharing different clinical signs due to a defect at the level of the primary cilia/centrosome complex. Postaxial polydactyly is frequently reported in ciliopathies, especially in Bardet-Biedl syndrome (BBS). Clinical features and genetic results observed in a pair of dizygotic twins with BBS are reported. The following manifestations were present: retinitis pigmentosa, bilateral insertional polydactyly, cognitive impairment and renal dysfunction. X-rays of the hands confirmed the presence of a 4th mesoaxial extra-digit with Y-shaped metacarpal bones. The sequencing of LZTFL1 identified a missense mutation (NM_020347.2: p.Leu87Pro; c.260T>C) and a nonsense mutation (p.Glu260*; c.778G>T), establishing a compound heterozygous status for the twins. A major decrease of LZTFL1 transcript and protein was observed in the patient's fibroblasts. This is the second report of LZTFL1 mutations in BBS patients confirming LZTFL1 as a BBS gene. Interestingly, the only two families reported in literature thus far with LZTFL1 mutations have in common mesoaxial polydactyly, a very uncommon feature for BBS. This special subtype of polydactyly in BBS patients is easily identified on clinical examination and prompts for priority sequencing of LZTFL1 (BBS17).

Clinical geneticists' views of VACTERL/VATER association

VACTERL association (sometimes termed "VATER association" depending on which component features are included) is typically defined by the presence of at least three of the following congenital malformations, which tend to statistically co-occur in affected individuals: Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula, Renal anomalies, and Limb abnormalities. Although the clinical criteria for VACTERL association may appear to be straightforward, there is wide variability in the way clinical geneticists define the disorder and the genetic testing strategy they use when confronted with an affected patient. In order to describe this variability and determine the most commonly used definitions and testing modalities, we present the results of survey responses by 121 clinical geneticists. We discuss the results of the survey responses, provide a literature review and commentary from a group of physicians who are currently involved in clinical and laboratory-based research on VACTERL association, and offer an algorithm for genetic testing in patients with this association.

Severe aortic stenosis, bicuspid aortic valve and atrial septal defect in a child with Joubert Syndrome and Related Disorders (JSRD) - a case report and review of congenital heart defects reported in the human ciliopathies

We report a case of a 2 year-old boy with Joubert Syndrome and Related Disorders (JSRD), severe congenital aortic stenosis, bicuspid aortic valve and an atrial septal defect. JSRD is one of a group of conditions known as 'ciliopathies', whose multi-organ involvement results from primary cilia dysfunction. To date, there have been no other reported cases of aortic stenosis and bicuspid aortic valve associated with JSRD. Cardiac screening is not currently recommended in the management guidelines for individuals suspected of having JSRD. We speculate that while the presence of congenital aortic stenosis in this child could be caused by an unrelated genetic mechanism, it could also represent a phenotypic overlap with another ciliopathy, Bardet Biedl syndrome, in which aortic stenosis is more commonly reported. We also review the range of cardiac malformations reported to be present in all human diseases known to be ciliopathies, in order to assist with the investigation and management of individuals with a suspected or proven ciliopathy.

Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy characterised by retinal dystrophy, obesity, post-axial polydactyly, renal dysfunction, learning difficulties and hypogonadism. Many associated minor features can be helpful in making a diagnosis and are important in the clinical management of BBS. The diagnosis is based on clinical findings and can be confirmed by sequencing of known disease-causing genes in 80% of patients. BBS genes encode proteins that localise to the cilia and basal body and are involved in cilia biogenesis and function. Mutations lead to defective cilia accounting in part for the pleiotropic effects observed in BBS. We provide an overview of BBS including the clinical findings, current understanding of cilia biology, and a practical approach to diagnosis, genetic counselling and up-to-date management.

Laparoscopically assisted vaginal pull-through for high urogenital sinus: a new surgical technique

OBJECTIVE

To evaluate feasibility and outcome of a laparoscopically assisted vaginal pull through procedure for suprasphincteric high urogenital sinus malformation with hydrometrocolpos and normal external genitalia.

METHODS

A tension-free anastomosis of the vagina to the perineum was realized after laparoscopic mobilization of the vagina, separation from the bladder neck at the confluence and pull-through via an externally introduced expandable trocar, thereby avoiding perineal or perirectal dissection.

RESULTS

The approach resulted in good cosmetic and unimpaired functional outcome. Voiding cystourethrography showed normal lower urinary tract anatomy. No disturbances of bladder function could be detected 2 years after surgery.

CONCLUSION

Laparoscopic assisted vaginal pull-through is a new approach for high UGS that significantly improved exposure of the uretro-vaginal junction, allowed extensive mobilization of the vagina and showed excellent cosmetic and functional result.

A case of McKusick-Kaufman syndrome

McKusick-Kaufman syndrome (MKS) is an autosomal recessive multiple malformation syndrome characterized by hydrometrocolpos (HMC) and postaxial polydactyly (PAP). We report a case of a female child with MKS who was transferred to the neonatal intensive care unit of Seoul National University Children's Hospital on her 15th day of life for further evaluation and management of an abdominal cystic mass. She underwent abdominal sonography, magnetic resonance imaging, genitography and cystoscopy which confirmed HMC with a transverse vaginal septum. X-rays of the hand and foot showed bony fusion of the left third and fourth metacarpal bones, right fourth dysplastic metacarpal bone and phalanx, right PAP and hypoplastic left foot with left fourth and fifth dysplastic metatarsal bones. In addition, she had soft palate cleft, mild hydronephroses of both kidneys, hypoplastic right kidney with ectopic location and mild rotation, uterine didelphys with transverse vaginal septum and low-type imperforated anus. She was temporarily treated with ultrasound-guided transurethral aspiration of the HMC. Our patient with HMC and PAP was diagnosed with MKS because she has two typical abnormality of MKS and she has no definite complications of retinal disease, learning disability, obesity and renal failure that develop in Bardet-Biedl syndrome, but not in MKS until 33 months of age. Here, we describe a case of a Korean patient with MKS.

Polydactyly: how many disorders and how many genes? 2010 update

Limb development is clinically and biologically important. Polydactyly is common and caused by aberrant anterior-posterior patterning. Human disorders that include polydactyly are diverse. To facilitate an understanding of the biology of limb development, cataloging the genes that are mutated in patients with polydactyly would be useful. In 2002, I characterized human phenotypes that included polydactyly. Subsequently, many advances have occurred with refinement of clinical entities and identification of numerous genes. Here, I update human polydactyly entities by phenotype and mutated gene. This survey demonstrates phenotypes with overlapping manifestations, genetic heterogeneity, and distinct phenotypes generated from mutations in single genes. Among 310 clinical entities, 80 are associated with mutations in 99 genes. These results show that knowledge of limb patterning genetics is improving rapidly. Soon, we will have a comprehensive toolkit of genes important for limb development, which will lead to regenerative therapies for limb anomalies.

Congenital vaginal obstruction in neonates and infants: recognition and management

BACKGROUND

Congenital vaginal obstruction commonly presents after puberty and presentation in infancy is uncommon. Due to lack of awareness, diagnosis may be missed in infants, sometimes with disastrous consequences.

METHOD

A retrospective review of 9 neonates and infants treated for congenital vaginal obstruction in 16 years.

RESULTS

The patients were aged 2 days to 4 months (median 28 days) at presentation. The main presenting feature was a lower abdominal mass, producing intestinal and urinary obstruction in 7 patients. In 2 patients, other conditions were suspected and diagnosis made only intraoperatively and in one patient, diagnosis was incidental during treatment for another condition. The cause of vaginal obstruction were low transverse vaginal septum 6, imperforate hymen 2, high transverse vaginal septum one. Associated anomalies were present in 5 patients (persistent cloaca 3, Hirschsprung disease 1, polydactyly 1). Low vaginal septum was treated by incision and drainage of hydrometrocolpos, imperforate hymen by hymenotomy and drainage of hydrometrocolpos and high vaginal septum by excision. There was recurrence of hydrometrocolpos in one patient who had low vaginal septum, requiring repeat surgery. One patient, in whom diagnosis was missed, died from overwhelming infection. Short term follow-up was good.

CONCLUSION

Congenital vaginal obstruction is an uncommon presentation in this setting. Missing the diagnosis can lead to disastrous consequences. A high index of suspicion is required for prompt recognition and treatment.

McKusick-Kaufman syndrome: the difficulty of establishing a prenatal diagnosis of an uncommon disorder

Prenatal evaluation of abdominal cystic masses can be complex and challenging. We report the case of a fetus with a large cystic abdominal mass and discuss how the differential diagnosis was narrowed to include McKusick-Kaufman syndrome (MKS). MKS is characterized by the triad of postaxial polydactyly, congenital heart disease, hydrometrocolpos, and genital malformations in males. Rare conditions such as MKS are difficult to diagnose prenatally and require postnatal phenotyping and molecular studies before a definitive diagnosis can be established.

Bardet-Biedl Syndrome in an African-American Patient: Should the Diagnostic Criteria Be Expanded to Include Hydrometrocolpos?

Bardet-Biedl Syndrome (BBS) is a multisystemic disorder diagnosed on the basis of a combination of primary and secondary clinical features that include retinal dystrophy, obesity, polydactyly, cognitive dysfunction, and renal malformations. We report a unique case of BBS in a 13-year old girl of African-American descent who presented with retinitis pigmentosa, obesity, polydactyly, learning disabilities, precocious puberty, hypertension, renal cysts, and Hirschprung disease. Further evaluation revealed a history of precocious puberty, which is antithetical to the common manifestations of BBS, while neuroimaging was suggestive of periventricular leukomalacia and neuro-electrophysiologic studies revealed diffuse cerebral disturbance, which may contribute to her neurological abnormalities. The patient was also diagnosed with hydrometrocolpos, a finding typical of McKusick-Kaufman Syndrome (MKKS) but infrequent in other disorders. This observation, together with recent findings in some mouse models of BBS, raises the question of whether hydrometrocolpos should be considered as an additional diagnostic criterion for BBS to be used in females in parallel to the criterion of hypogonadism in males, thereby improving diagnostic sensitivity.

SNP array mapping of chromosome 20p deletions: genotypes, phenotypes, and copy number variation

The use of array technology to define chromosome deletions and duplications is bringing us closer to establishing a genotype/phenotype map of genomic copy number alterations. We studied 21 patients and five relatives with deletions of the short arm of chromosome 20 using the Illumina HumanHap550 SNP array to: 1) more accurately determine the deletion sizes; 2) identify and compare breakpoints; 3) establish genotype/phenotype correlations; and 4) investigate the use of the HumanHap550 platform for analysis of chromosome deletions. Deletions ranged from 95 kb to 14.62 Mb, and all of the breakpoints were unique. Eleven patients had deletions between 95 kb and 4 Mb and these individuals had normal development, with no anomalies outside of those associated with Alagille syndrome (AGS). The proximal and distal boundaries of these 11 deletions constitute a 5.4-Mb region, and we propose that haploinsufficiency for only 1 of the 12 genes in this region causes phenotypic abnormalities. This defines the JAG1-associated critical region, in which deletions do not confer findings other than those associated with AGS. The other 10 patients had deletions between 3.28 Mb and 14.62 Mb, which extended outside the critical region, and, notably, all of these patients had developmental delay. This group had other findings such as autism, scoliosis, and bifid uvula. We identified 47 additional polymorphic genome-wide copy number variants (>20 SNPs), with 0 to 5 variants called per patient. Deletions of the short arm of chromosome 20 are associated with relatively mild and limited clinical anomalies. The use of SNP arrays provides accurate high-resolution definition of genomic abnormalities.

[Bardet-Biedl syndrome]

Bardet-Biedl syndrome (BBS) is a ciliopathy causing multivisceral abnormalities. Its prevalence in Europe is from 1/125,000 to 1/175,000. This disorder is defined by a combination of clinical signs: obesity, pigmentary retinopathy, post-axial polydactyly, polycystic kidneys, hypogenitalism, and learning disabilities, many of which appearing after several years of evolution. Individual clinical phenotype is highly variable. Most signs are present in a majority of patients but only pigmentary retinopathy is constant after infancy. There are many other associated minor clinical signs including diabetes, blood hypertension, congenital cardiopathy or Hirschsprung disease. This broad clinical spectrum is associated to a great genetic heterogeneity, with mainly an autosomal recessive transmission and, sometimes cases of oligogenism. To date, mutations in 12 different genes (BBS1 to BBS12) are responsible for this phenotype. These genes code for proteins involved in the development and function of primary cilia. Absent or non functional BBS proteins affect cilia in certain organs such as kidney or eye. However, some symptoms are still not clearly related to cilia dysfunction. BB syndrome has to be recognized because a molecular diagnosis is possible and will lead to familial genetic counseling and possibly prenatal diagnosis. Patients with BBS will need a multidisciplinary medical care. The renal abnormalities are the main life-threatening features because they can lead to end-stage renal failure and renal transplantation. Retinal dystrophy leading to progressive vision loss, moderate mental retardation, and obesity will affect social life of these patients.

Hydrometrocolpos and acute renal failure: a rare neonatal presentation of Bardet-Biedl syndrome

The presence of hydrometrocolpos and postaxial polydactyly in a neonate can be caused by two genetic conditions; namely, McKusick-Kaufman syndrome and Bardet-Biedl syndrome. There are no distinct clinical features that allow discrimination between the two syndromes, as the cardinal features of rod-cone dystrophy, obesity, learning disability and renal dysfunction in Bardet-Biedl syndrome are age dependent. McKusick-Kaufman syndrome is characterized by vaginal atresia with hydrometrocolpos, postaxial polydactyly and congenital heart defect. Here we report an unusual presentation of Bardet-Biedl syndrome: a neonate born in a consanguineous family having an older sibling diagnosed with Bardet-Biedl syndrome presenting with postaxial polydactyly and vaginal atresia; the latter causing hydrometrocolpos, hydronephrosis and renal failure. Relief of urinary obstruction by exploratory laparotomy and aspiration of fluid, and vaginal reconstruction gradually reversed the hydronephrosis and renal failure. The patient developed end-stage renal failure towards the end of her first decade, possibly due to underlying renal pathology associated with Bardet-Biedl syndrome.

Fetal urogenital sinus with consecutive hydrometrocolpos because of labial fusion: prenatal diagnostic difficulties and postpartal therapeutic management

OBJECTIVE

To elucidate the differential diagnoses of tumorous dilations in the fetal pelvic region detected by prenatal ultrasound and the postnatal management demonstrated on a fetus with 29 weeks of gestation with a retrovesical located bottle-like cystic structure measuring 54 x 31 x 27 mm within the pelvis. Postnatal findings were a labial fusion and a consecutive hydrometrocolpos due to a urethrovaginal fistula.

METHOD

Case report of a fetus affected by an intricate cloacal anomaly.

RESULTS

The long-term prognosis for this nonsyndromic form of hydrometrocolpos without any other structural defects or organic failures after operative sanitation is excellent. Final reconstruction is planned at about 12 months of age.

CONCLUSION

Prenatal diagnosis of tumorous dilations in the fetal pelvic region often involves difficulties because of numerous differential diagnoses and possible presentation in late pregnancy. Magnetic resonance imaging could be a useful complementary tool for assessing these anomalies when ultrasonography is inconclusive. In some cases, the final diagnosis cannot be confirmed until after delivery.

[Mirror hand deformity: a new phenotype with literature review]

We report the case of a child who presented polydactyly with eight triphalangeal fingers, no thumb or radius and ulnar dimelia. Hand, wrist, forearm and elbow function was compromised, particularly due to wrist stiffness in flexion, the absence of forearm pronation supination and severe limitation of elbow motion. In addition, the child underwent surgery for pyloric hypertrophy and also presented a multicystic kidney. We present the clinical, anatomic, electromyographic, genetic and therapeutic aspects of this rare deformity and discuss data presented in the literature.

The retinal ciliopathies

While the functions of many of the proteins located in or associated with the photoreceptor cilia are poorly understood, disruption of the function of these proteins may result in a wide variety of phenotypes ranging from isolated retinal degeneration to more pleiotropic phenotypes. Systemic findings include neurosensory hearing loss, developmental delay, situs-inversus, infertility, disorders of limb and digit development, obesity, kidney disease, liver disease, and respiratory disease. The concept of "retinal ciliopathies" brings to attention the importance of further molecular analysis of this organelle as well as provides a potential common target for therapies for these disorders. The retinal ciliopathies include retinitis pigmentosa, macular degeneration, cone-dystrophy, cone-rod dystrophy, Leber congenital amaurosis, as well as retinal degenerations associated with Usher syndrome, primary ciliary dyskinesia, Senior-Loken syndrome, Joubert syndrome, Bardet-Biedl syndrome, Laurence-Moon syndrome, McKusick-Kaufman syndrome, and Biemond syndrome. Mutations for these disorders have been found in retinitis pigmentosa-1 (RP1), retinitis pigmentosa GTPase regulator (RPGR), retinitis pigmentosa GTPase regulator interacting protein (RPGR-IP), as well as the Usher, Bardet-Biedl, and nephronophthisis genes. Other systemic disorders associated with retinal degenerations that may also involve ciliary abnormalities include: Alstrom, Edwards-Sethi, Ellis-van Creveld, Jeune, Meckel-Gruber, Orofaciodigital Type 9, and Gurrieri syndromes. Understanding these conditions as ciliopathies may help the ophthalmologist to recognize associations between seemingly unrelated diseases and have a high degree of suspicion that a systemic finding may be present.

Mutational analyses of UPIIIA, SHH, EFNB2 and HNF1beta in persistent cloaca and associated kidney malformations

OBJECTIVES

'Persistent cloaca' is a severe malformation affecting females in which the urinary, genital and alimentary tracts share a single conduit. Previously, a Uroplakin IIIA (UPIIIA) mutation was reported in one individual with persistent cloaca, and UPIIIA, Sonic Hedgehog (SHH), Ephrin B2 (EFNB2) and Hepatocyte Nuclear Factor 1beta (HNF1beta) are expressed during the normal development of organs that are affected in this condition. HNF1beta mutations have been associated with uterine malformations in humans, and mutations of genes homologous to human SHH or EFNB2 cause persistent cloaca in mice.

PATIENTS AND METHODS

We sought mutations of coding regions of UPIIIA, SHH, EFNB2 and HNF1beta genes by direct sequencing in a group of 20 patients with persistent cloaca. Most had associated malformations of the upper renal tract and over half had impaired renal excretory function. The majority of patients had congenital anomalies outside the renal/genital tracts and two had the VACTERL association.

RESULTS

Apart from a previously described index case, we failed to find UPIIIA mutations, and no patient had a SHH, EFNB2 or HNF1beta mutation.

CONCLUSION

Persistent cloaca is only rarely associated with UPIIIA mutation. Despite the fact that SHH and EFNB2 are appealing candidate genes, based on their expression patterns and mutant mice phenotypes, they were not mutated in these humans with persistent cloaca. Although HNF1beta mutations can perturb paramesonephric duct fusion in humans, HNF1beta was not mutated in persistent cloaca.

Homozygosity mapping with SNP arrays identifies TRIM32, an E3 ubiquitin ligase, as a Bardet-Biedl syndrome gene (BBS11)

The identification of mutations in genes that cause human diseases has largely been accomplished through the use of positional cloning, which relies on linkage mapping. In studies of rare diseases, the resolution of linkage mapping is limited by the number of available meioses and informative marker density. One recent advance is the development of high-density SNP microarrays for genotyping. The SNP arrays overcome low marker informativity by using a large number of markers to achieve greater coverage at finer resolution. We used SNP microarray genotyping for homozygosity mapping in a small consanguineous Israeli Bedouin family with autosomal recessive Bardet-Biedl syndrome (BBS; obesity, pigmentary retinopathy, polydactyly, hypogonadism, renal and cardiac abnormalities, and cognitive impairment) in which previous linkage studies using short tandem repeat polymorphisms failed to identify a disease locus. SNP genotyping revealed a homozygous candidate region. Mutation analysis in the region of homozygosity identified a conserved homozygous missense mutation in the TRIM32 gene, a gene coding for an E3 ubiquitin ligase. Functional analysis of this gene in zebrafish and expression correlation analyses among other BBS genes in an expression quantitative trait loci data set demonstrate that TRIM32 is a BBS gene. This study shows the value of high-density SNP genotyping for homozygosity mapping and the use of expression correlation data for evaluation of candidate genes and identifies the proteasome degradation pathway as a pathway involved in BBS.

An unusual cause of acute renal failure in a newborn: hydrometrocolpos

Here we report on an unusual cause of acute renal failure in a newborn: hydrometrocolpos due to imperforate hymen. Hymenotomy resolved all of the laboratory and clinical abnormalities of the patient and the baby was sent home healthy.

[Update on Bardet-Biedl syndrome]

Until recently, Bardet-Biedl syndrome was considered as a classic autosomal recessive condition. The disorder is defined by the association of the following clinical features: retinitis pigmentosa, polydactyly, obesity, hypogonadism, and possible mental retardation. This syndrome leads to multiple handicaps (visual impairment, complications of obesity, kidney failure, endocrine dysfunction). This condition, apparently clearly defined from a clinical point of view, appears to be genetically heterogenous. To date, six different genes have been identified: BBS1, BBS2, BBS4, BBS6, BBS7 and BBS8. Interestingly, this condition has recently been linked to a failure of cellular ciliogenesis. Moreover, this disorder is characterized by an additional degree of complexity, as it is the first example of triallelic inheritance described in human beings. However, this new finding appears to be less frequent than expected in this syndrome.