Fraser syndrome with limb reduction defect: a rare and unique anatomic variation.

INTRODUCTION: Fraser syndrome, named after George Fraser, is an autosomal recessive disorder showing a highly variable interfamilial phenotypic variation, with malformations ranging from minor symptoms to lethal anomalies like renal agenesis, incompatible with survival. Limb reduction defects have not been reported to be associated with it. CASE PRESENTATION: A 21-year-old primigravida presented to the antenatal outpatient department with a level two targeted anomaly scan report suggestive of severe oligohydramnios with suspected renal agenesis. The cranial vault bones were compressed, and orbital globes and lenses could not be visualized. Renal agenesis was confirmed due to sleeping adrenals sign, non-visualization of the urinary bladder, and Doppler of renal arteries. A detailed examination of the fetal head in the sagittal section showed the absence of an eye globe and lens, arousing suspicion of Fraser syndrome. After pregnancy termination, a complete fetal autopsy was done to look for any additional findings. CONCLUSION: Patients who have a syndromic mix of acrofacial and urogenital abnormalities with or without cryptophthalmos should be evaluated for Fraser syndrome, which can be diagnosed by clinical examination and perinatal autopsy.

Transgene-mediated skeletal phenotypic variation in zebrafish.

When considering relationships between genotype and phenotype we frequently ignore the fact that the genome of a typical animal, notably including that of a fish and a human, harbours a huge amount of foreign DNA. Such DNA, in the form of transposable elements, can affect genome function in a major way, and transgene biology needs to be included in our understanding of the genome. Here we examine an unexpected phenotypic effect of the chromosomally integrated transgene fli1a-F-hsp70l:Gal4VP16 that serves as a model for transgene function generally. We examine larval fras1 mutant zebrafish (Danio rerio). Gal4VP16 is a potent transcriptional activator that is already well known for toxicity and mediating unusual transcriptional effects. In the presence of the transgene, phenotypes in the neural crest-derived craniofacial skeleton, notably fusions and shape changes associated with loss of function fras1 mutations, are made more severe, as we quantify by scoring phenotypic penetrance, the fraction of mutants expressing the trait. A very interesting feature is that the enhancements are highly specific for fras1 mutant phenotypes, occurring in the apparent absence of more widespread changes. Except for the features due to the fras1 mutation, the transgene-bearing larvae appear generally healthy and to be developing normally. The transgene behaves as a genetic partial dominant: a single copy is sufficient for the enhancements, yet, for some traits, two copies may exert a stronger effect. We made new strains bearing independent insertions of the fli1a-F-hsp70l:Gal4VP16 transgene in new locations in the genome, and observed increased severities of the same phenotypes as observed for the original insertion. This finding suggests that sequences within the transgene, for example Gal4VP16, are responsible for the enhancements, rather than the effect on neighbouring host sequences (such as an insertional mutation). The specificity and biological action underlying the traits are subjects of considerable interest for further investigation, as we discuss. Our findings show that work with transgenes needs to be undertaken with caution and attention to detail.

Characteristic dental pattern with hypodontia and short roots in Fraser syndrome.

Fraser syndrome (FS) is a rare autosomal recessive multiple congenital malformation syndrome characterized by cryptophthalmos, cutaneous syndactyly, renal agenesis, ambiguous genitalia, and laryngotracheal anomalies. It is caused by biallelic mutations of FRAS1, FREM2, and GRIP1 genes, encoding components of a protein complex that mediates embryonic epithelial-mesenchymal interactions. Anecdotal reports have described abnormal orodental findings in FS, but no study has as yet addressed the orodental findings of FS systematically. We reviewed dental radiographs of 10 unrelated patients with FS of different genetic etiologies. Dental anomalies were present in all patients with FS and included hypodontia, dental crowding, medial diastema, and retained teeth. A very consistent pattern of shortened dental roots of most permanent teeth as well as altered length/width ratio with shortened dental crowns of upper incisors was also identified. These findings suggest that the FRAS1-FREM complex mediates critical mesenchymal-epithelial interactions during dental crown and root development. The orodental findings of FS reported herein represent a previously underestimated manifestation of the disorder with significant impact on orodental health for affected individuals. Integration of dentists and orthodontists into the multidisciplinary team for management of FS is therefore recommended.

Two unrelated families with variable expression of Fraser syndrome due to the same pathogenic variant in the FRAS1 gene.

We report on two unrelated families of Polish origin with variable expression of Fraser syndrome (FS; MIM#219000) due to homozygosity for the same pathogenic variant, c.6963_6964dup, of FRAS1. In one family, the disorder presented with perinatal and prenatal lethality. One affected female from family 2 who was followed-up for 32 years, represented a relatively favorable long-term outcome. She displayed the typical craniofacial dysmorphism, including right cryptophthalmos, cutaneous syndactyly, abnormalities of the stomathognatic system, bilateral atresia of the external ear canals resulting in conductive hearing loss, and malformations of the larynx, spleen, kidney, and genitourinary tract. Her intellectual capacities were normal. Our observations illustrate that expression and severity of FS, even when caused by the same pathogenic variant, may be quite different ranging from a lethal disorder to a condition with multiple physical malformations but normal psychomotor development. In addition, we propose that the FRAS1 c.6963_6964dup variant may be a founder mutation in the Polish population. Therefore, it would be reasonable to test specifically for this variant first in any FS1 patient of Polish ancestry.

Bilateral anophthalmia and intrahepatic biliary atresia, two unusual components of Fraser syndrome: a case report.

BACKGROUND: Fraser syndrome or "cryptophthalmos syndrome" is a rare autosomal recessive disease. It is characterized by a group of congenital malformations such as: crytophthalmos, syndactyly, abnormal genitalia, and malformations of the nose, ears, and larynx. Although cryptophthalmos is considered as a main feature of Fraser syndrome, its absence does not exclude the diagnosis. Clinical diagnosis can be made by Thomas Criteria. Here we present the first documented case of Fraser Syndrome in Aleppo, Syria that is characterized by bilateral anophthalmia and intrahepatic biliary atresia. CASE PRESENTATION: During pregnancy, several ultrasound scans revealed hyperechoic lungs, ascites, and unremarkable right kidney at the 19th-week visit; bilateral syndactyly on both hands and feet at the 32nd-week visit. On the 39th week of gestation, the stillborn was delivered by cesarean section due to cephalopelvic disproportion. Gross examination showed bilateral anophthalmia, bilateral syndactyly on hands and feet, low set ears, and ambiguous genitalia. Microscopic examination of the lung, spleen, liver, ovary, and kidneys revealed abnormalities in these organs. CONCLUSION: The diagnosis of Fraser syndrome can be made prenatally and postnatally; prenatally by ultrasound at 18 weeks of gestation and postnatally by clinical examination using Thomas criteria. Moreover, intrahepatic biliary atresia was not described previously with Fraser syndrome; this recommends a more detailed pathologic study for Fraser syndrome cases.

Diagnosis of Fraser syndrome missed out until the age of six months old in a low-resource setting: a case report.

BACKGROUND: Fraser syndrome is a rare genetic disorder that often presents with ocular, renal, genital and limb's congenital anomalies. The prognosis of this genetic disorder depends on the severity of the combination of congenital malformations, some of which may be fatal. The diagnosis of Fraser syndrome is based on established clinical criteria and genetic tests. The criteria enabling clinical diagnosis are visible dysmorphic features present at birth, hence, Fraser syndrome can easily diagnosed at birth, except when health professionals are inexperienced in clinical recognition. Herein, we report a case of Fraser syndrome missed out at birth and fortuitously diagnosed at the age of six months in a bid to raise clinicians' awareness, particularly in resource-limited settings. CASE PRESENTATION: We report a case of a six-month-old Cameroonian female infant, born at home and taken the following day to a primary healthcare facility for neonatal care. Her mother had no antenatal care until birth. She presented at our health center with respiratory distress and fever. She had a temperature of 38.8 °C and signs of left lung basal consolidation, suggestive of a left lower lober pneumonia, confirmed on chest x-ray. Other incidental clinical findings were several dysmorphic features like bilateral cryptophthalmos, nasal malformation, anal imperforation (with a perianal fistula), an external genital anomaly and syndactyly characteristic of Fraser syndrome associated with pneumonia. The patient responded well to intravenous antibiotics for the treatment of her pneumonia. Thereafter, she was referred to a pediatric surgeaon for surgical corrections of her bilateral cryptophthalmos, anal imperforation, external genital defect and syndactyly. CONCLUSION: Here we presented a case of Fraser syndrome in a Cameroonian infant whose diagnosis was missed out at birth and fortuitously made at six months of age. In view of the serious and potentially fatal complications of this genetic disorder, we draw clinicians' attention, especially obstetricians, midwives and pediatricians for a high index of clinical suspicion geared at a timely diagnosis and management. Also, for a timely diagnosis, health education on regular antenatal and postnatal follow ups of  the mother-infant couple respectively, cannot be overemphasized.

Locating the Level and Extent of Congenital High Airway Obstruction: Fluid in the Airway Tract as Reference Points.

Described here are a series of four cases of congenital high airway obstruction in the fetus. All of the patients presented in the second trimester and all had hydrops fetalis. Three cases had bilateral hyperinflated lungs, midline shift of heart, flattening or inversion of the diaphragm, and fetal ascites. Autopsy was performed in one of these three and showed laryngeal atresia. In one fetus, there was only a unilateral huge enlargement of the lung with mediastinal shift. On autopsy, this fetus had atresia of right main bronchus. All parents had terminated the pregnancy following the prenatal diagnosis. Laryngeal atresia is an extremely rare fetal anomaly with dismal prognosis. It is important to differentiate the condition from other lesions with a more favorable prognosis, such as congenital adenomatoid malformation of the lung. Much research is needed in the future to explore the therapeutic options, including fetoscopic intervention or transplantation of stem cell-derived airways.

Syndactyly in a novel Fras1(rdf) mutant results from interruption of signals for interdigital apoptosis.

BACKGROUND: Fras1 encodes an extracellular matrix protein that is critical for the establishment of the epidermal basement membrane during gestation. In humans, mutations in FRAS1 cause Fraser Syndrome (FS), a pleiotropic condition with many clinical presentations such as limb, eye, kidney, and craniofacial deformations. Many of these defects are mimicked by loss of Fras1 in mice, and are preceded by the formation of epidermal blisters in utero. RESULTS: In this study, we identified a novel ENU-derived rounded foot (rdf) mouse mutant with highly penetrant hindlimb soft-tissue syndactyly, among other structural defects. Mapping and sequencing revealed that rdf is a novel loss-of-function nonsense allele of Fras1 (Fras1(rdf)). Focusing on the limb, we found that the Fras1(rdf) syndactyly phenotype originates from loss of interdigital cell death (ICD). Despite normal expression of bone morphogenetic protein (BMP) ligands and their receptors, the BMP downstream target gene Msx2, which is also necessary and sufficient to promote ICD, was down-regulated in the interdigital regions of Fras1(rdf) hindlimb buds. CONCLUSIONS: The close correlation between limb bud epidermal blistering, decreased Msx2 expression, and reduced ICD in the Fras1(rdf) hindlimb buds suggests that epithelium detachment from the mesenchyme may create a physical gap that interrupts the transmission of BMP, among other signals, resulting in soft tissue syndactyly.

Mesenchymal expression of the FRAS1/FREM2 gene unit is decreased in the developing fetal diaphragm of nitrofen-induced congenital diaphragmatic hernia.

PURPOSE: Developmental mutations that inhibit normal formation of extracellular matrix (ECM) in fetal diaphragms have been identified in congenital diaphragmatic hernia (CDH). FRAS1 and FRAS1-related extracellular matrix 2 (FREM2), which encode important ECM proteins, are secreted by mesenchymal cells during diaphragmatic development. The FRAS1/FREM2 gene unit has been shown to form a ternary complex with FREM1, which plays a crucial role during formation of human and rodent diaphragms. Furthermore, it has been demonstrated that the diaphragmatic expression of FREM1 is decreased in the nitrofen-induced CDH model. We hypothesized that FRAS1 and FREM2 expression is decreased in the developing diaphragms of fetal rats with nitrofen-induced CDH. METHODS: Pregnant rats were exposed to either nitrofen or vehicle on gestational day 9 (D9), and fetuses were harvested on D13, D15 and D18. Microdissected diaphragms were divided into nitrofen-exposed/CDH and control samples (n = 12 per time-point and experimental group, respectively). Diaphragmatic gene expression levels of FRAS1 and FREM2 were analyzed by qRT-PCR. Immunofluorescence double staining for FRAS1 and FREM2 was combined with the mesenchymal marker GATA4 in order to evaluate protein expression and localization in pleuroperitoneal folds (PPFs) and fetal diaphragmatic tissue. RESULTS: Relative mRNA expression of FRAS1 and FREM2 were significantly reduced in PPFs of nitrofen-exposed fetuses on D13 (1.76 ± 0.86 vs. 3.09 ± 1.15; p < 0.05 and 0.47 ± 0.26 vs. 0.82 ± 0.36; p < 0.05), developing diaphragms of nitrofen-exposed fetuses on D15 (1.45 ± 0.80 vs. 2.63 ± 0.84; p < 0.05 and 0.41 ± 0.16 vs. 1.02 ± 0.49; p < 0.05) and fully muscularized diaphragms of CDH fetuses on D18 (1.35 ± 0.75 vs. 2.32 ± 0.92; p < 0.05 and 0.37 ± 0.24 vs. 0.70 ± 0.32; p < 0.05) compared to controls. Confocal laser scanning microscopy revealed markedly diminished FRAS1 and FREM2 immunofluorescence in diaphragmatic mesenchyme, which was associated with reduced proliferation of mesenchymal cells in nitrofen-exposed PPFs and fetal CDH diaphragms on D13, D15 and D18 compared to controls. CONCLUSION: Decreased mesenchymal expression of FRAS1 and FREM2 in the nitrofen-induced CDH model may cause failure of the FRAS1/FREM2 gene unit to activate FREM1 signaling, disturbing the formation of diaphragmatic ECM and thus contributing to the development of diaphragmatic defects in CDH.

Mild recessive mutations in six Fraser syndrome-related genes cause isolated congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) account for approximately 40% of children with ESRD in the United States. Hitherto, mutations in 23 genes have been described as causing autosomal dominant isolated CAKUT in humans. However, >90% of cases of isolated CAKUT still remain without a molecular diagnosis. Here, we hypothesized that genes mutated in recessive mouse models with the specific CAKUT phenotype of unilateral renal agenesis may also be mutated in humans with isolated CAKUT. We applied next-generation sequencing technology for targeted exon sequencing of 12 recessive murine candidate genes in 574 individuals with isolated CAKUT from 590 families. In 15 of 590 families, we identified recessive mutations in the genes FRAS1, FREM2, GRIP1, FREM1, ITGA8, and GREM1, all of which function in the interaction of the ureteric bud and the metanephric mesenchyme. We show that isolated CAKUT may be caused partially by mutations in recessive genes. Our results also indicate that biallelic missense mutations in the Fraser/MOTA/BNAR spectrum genes cause isolated CAKUT, whereas truncating mutations are found in the multiorgan form of Fraser syndrome. The newly identified recessive biallelic mutations in these six genes represent the molecular cause of isolated CAKUT in 2.5% of the 590 affected families in this study.

Delivery of anesthesia and complications for children with Fraser syndrome: a review of 125 anesthetics.

OBJECTIVES: To perform a retrospective, anesthesia case note review of patients with Fraser syndrome. AIM: To identify the perioperative and postoperative anesthetic management and complications in this patient group. BACKGROUND: Fraser syndrome is a rare, autosomal recessively inherited disorder characterized by cryptophthalmos, cutaneous syndactyly, and ambiguous genitalia. It also has variable association with cardiac, laryngeal, tracheal, and gastrointestinal abnormalities. Children with Fraser syndrome present for a variety of surgical and radiological procedures, and there are a number of single case reports in the literature. METHODS: A retrospective case note review was undertaken on 10 children with Fraser syndrome who presented to our institution over a 30-year period. Analysis of the medical notes and general anesthetic records was undertaken, and the conduct of anesthesia, spectrum of disease, genetic markers, and perioperative complications were recorded. There were a total of 125 procedures performed under general anesthesia during this period. RESULTS: There were a total of ten anesthetic complications in the review, all related to management of the airway. There were two accidental extubations, five recorded incidents of airway obstruction (which were relieved with continuous positive airway pressure (CPAP)) and one posttracheostomy airway bleed. One child was a difficult intubation requiring an ID 2.5 mm oral endotracheal tube (ETT), and one child was an impossible intubation that required an emergency tracheostomy to secure the airway. CONCLUSIONS: There was a low incidence of complications with this group of patients. However, there is a relatively high incidence of difficult or impossible tracheal intubation (20%) due to glottic stenosis and one patient required an emergency tracheostomy despite no previous clinical evidence of airway narrowing.

[About a case of Fraser syndrome. Autopsy of a 37 weeks gestation fetus with multiple malformations]. / A propósito de un caso de síndrome de Fraser. Autopsia de un feto de 37 semanas de gestación con múltiples malformaciones.

Fraser syndrome or cryptophthalmos-syndactyly syndrome is a rare genetic disease, the diagnosis of which is based on a series of major and minor clinical criteria and that can be supported by genetic tests. This article presents the case of a fetal autopsy at 37 weeks of gestation with suspicion of CHAOS syndrome (congenital obstructive syndrome of the upper airways).

Ablepharon macrostomia syndrome: A distinct genetic entity clinically related to the group of FRAS-FREM complex disorders.

Ablepharon macrostomia syndrome (AMS; OMIM 200110) is an extremely rare congenital malformation syndrome. It overlaps clinically with Fraser syndrome (FS; OMIM 219000), which is known to be caused by mutations in either FRAS1, FREM2, or GRIP1, encoding components of a protein complex that plays a role in epidermal-dermal interactions during morphogenetic processes. We explored the hypothesis that AMS might be either allelic to FS or caused by mutations in other genes encoding known FRAS1 interacting partners. No mutation in either of these genes was found in a cohort of 11 patients with AMS from 10 unrelated families. These findings demonstrate that AMS is genetically distinct from FS. It is proposed that it constitutes a separate entity within the group of FRAS-FREM complex disorders.

A Rare Case of Complete Cryptophthalmos and Suspected Fraser's Syndrome in a Female Neonate.

Cryptophthalmos is a rare congenital eye anomaly characterized by the absence of the palpebral fissure. Cryptophthalmos is often associated with Fraser's syndrome. We present a case of 3 days old female Asian neonate with complete unilateral cryptophthalmos, with the absence of a right eyelid. On inspection, there is an absence of eyelid, eyebrow and eyelashes in the right eye, collectively known as adnexal structures. The left eye was apparently normal. As per the parent's decision, surgical intervention was not pursued due to the poor visual prognosis. We advised prenatal genetic screening and testing for future pregnancies. These findings suggest the importance of genetic counseling and testing in cases of cryptophthalmos to identify potential genetic mutations and facilitate appropriate management.

Heterozygous Variants in FREM2 Are Associated with Mesiodens, Supernumerary Teeth, Oral Exostoses, and Odontomas.

BACKGROUND: Supernumerary teeth refer to extra teeth that exceed the usual number of dentitions. A mesiodens is a particular form of supernumerary tooth, which is located in the premaxilla region. The objective of the study was to investigate the genetic etiology of extra tooth phenotypes, including mesiodens and isolated supernumerary teeth. METHODS: Oral and radiographic examinations and whole-exome sequencing were performed on every patient in our cohort of 122 patients, including 27 patients with isolated supernumerary teeth and 94 patients with mesiodens. A patient who had multiple supernumerary teeth also had odontomas. RESULTS: We identified a novel (c.8498A>G; p.Asn2833Ser) and six recurrent (c.1603C>T; p.Arg535Cys, c.5852G>A; p.Arg1951His, c.6949A>T; p.Thr2317Ser; c.1549G>A; p.Val517Met, c.1921A>G; p.Thr641Ala, and c.850G>C; p.Val284Leu) heterozygous missense variants in FREM2 in eight patients with extra tooth phenotypes. CONCLUSIONS: Biallelic variants in FREM2 are implicated in autosomal recessive Fraser syndrome with or without dental anomalies. Here, we report for the first time that heterozygous carriers of FREM2 variants have phenotypes including oral exostoses, mesiodens, and isolated supernumerary teeth.

Cryptophthalmos: associated syndromes and genetic disorders.

PURPOSE: Cryptophthalmos is a rare congenital condition caused by anomalous eyelid development where the eyelid folds do not develop or fail to separate. Cryptophthalmos can be unilateral or bilateral and can occur in isolation or as part of an underlying syndrome. We aim to identify genetic syndromes associated with cryptophthalmos to facilitate genetic diagnosis. METHODS: We performed a retrospective medical record review of all patients diagnosed with cryptophthalmos followed at a single center between 2000 and 2020. The analysis included medical history, clinical examination findings, and genetic testing results. RESULTS: Thirteen patients were included, 10 (77%) males, mean age of 2.4 years. Eight (61%) had bilateral cryptophthalmos, and 4 (31%) had complete cryptophthalmos. Associated ocular abnormalities included corneal opacities (13/13, 100%), upper eyelid colobomas (12/13, 92%), and microphthalmia/clinical anophthalmia (3/13, 23%). All cases of complete cryptophthalmos had bilateral disease. An underlying clinical or molecular diagnosis was identified in 10/13 (77%) cases, including Fraser syndrome (n = 5), amniotic band syndrome (n = 1), FREM1-related disease (n = 1), Goldenhar versus Schimmelpenning syndrome (n = 1), MOTA syndrome (n = 1), and CELSR2-related disease (n = 1). CONCLUSION: This is the first report of a possible association between cryptophthalmos and biallelic CELSR2 variants. Children with cryptophthalmos, especially those with extra-ocular involvement, should be referred for comprehensive genetic evaluation.

FREM2-related Fraser syndrome with popliteal pterygium and structural central nervous system anomalies.

Fraser syndrome (FS) is a rare multiple malformation disorder characterized by cryptophthalmos, characteristic craniofacial dysmorphism, cutaneous syndactyly, malformations of the respiratory and urinary tract, and anogenital anomalies. Although the characteristic presentation of FS can be detected prenatally, oligohydramnios often challenges the clinical diagnosis. Here we report on the atypical prenatal and postmortem findings of a fetus with FS caused by a novel homozygous frameshift variant in FREM2. Our study highlights the variable manifestations of the FS and expands the clinical spectrum to include popliteal pterygium and structural central nervous system anomalies.

A Rare Case of Fraser Syndrome with Partial Vaginal Agenesis and Its Successful Reconstructive Cosmetic Management: A Case Report.

Fraser syndrome is a rare disorder with autosomal recessive inheritance having a wide spectrum of phenotypic appearances. A fourteen-year-old female presented to us with a chief complaint of acute retention of urine without any cyclical abdominal pain with syndromic appearance. She had partial vaginal agenesis which was treated by successful reconstructive surgery by lotus petal flap technique followed by recanalisation. Objective of this report is to highlight the rare disease of Fraser syndrome along with successful rare surgical management.

Fraser Syndrome: A Stumbling Block for the Anaesthesiologist.

Fraser syndrome is a rare autosomal recessive disorder with spectrum of malformations. Gamut of abnormal airway includes high arched palate, laryngeal atresia, hypoplasia, laryngeal stenosis etc. Laryngeal intubation difficulties have often been reported in literature. Airway management and decision process leading to emergency tracheostomy in these children has been discussed.

Whole exome sequencing identifies a novel FRAS1 mutation and aids in vitro fertilization with preimplantation genetic diagnosis in Fraser syndrome.

OBJECTIVE: To demonstrate the picture of a woman who had three times of pregnancies but fetuses were complicated with Fraser syndrome, a rare genetic disorder with multiple congenital anomalies. CASE REPORT: Here are three complicated pregnancies with predominant features of severe oligohydramnios and other variable intrafamilial presentations. We made a definite diagnosis, Fraser syndrome, with the assistance of whole exome sequencing (WES) via umbilical blood of the second and third fetus. The provision of a preimplantation diagnosis helped contribute a healthy newborn in this family. CONCLUSION: This paper provides insights into obscure antenatal presentations of Fraser syndrome with intrafamilial variance. Clinical uncertainty at the fetal stage suggests the role of WES to reach a final diagnosis, and a preimplantation diagnosis is applicable to avoid recurrence of genetic disorders in subsequent pregnancies.