Spectrum ofHLXB9gene mutations in Currarino syndrome and genotype-phenotype correlation

Currarino syndrome with immature teratoma: A case report with review of literature

ABSTRACT

Currarino syndrome (CS) is a rare congenital syndrome characterized by a triad of anorectal malformation, sacral deformity, and presacral mass. In about 50% of cases, it is caused by HLXB9 gene mutation in chromosome 7q36. A 13-month-male child presented with presacral discharging sinus with a history of surgery for anorectal malformation and perineal fistula at the time of birth. On detailed investigation, the child revealed to have anal atresia, hemisacrum, and presacral mass. Histopathology of presacral mass showed features of immature teratoma. The presacral mass in CS is mostly an anterior myelomeningocele or presacral teratoma. The development of immature teratoma in presacral mass is very rare. The histopathological identification of immature component of teratoma in the presacral mass of CS is important for risk stratification and further management. Suspicion of CS should be raised in any child presenting with partial phenotype of the triad.

Sacral agenesis without maternal diabetes: a case report

Introduction

Sacral agenesis is a rare congenital condition that is characterized by sacrococcygeal bone agenesis. It is associated with spinal cord anomalies as well as problems with the genitourinary system, large bowel, and lower extremities. Fetal ultrasound allows for diagnosis even before birth.

Case presentation

The authors present the case of a 1-year-old girl with sacral agenesis type III and bilateral congenital talipes equinovarus with spina bifida who was born to a nondiabetic mother and had a normal anomaly scan.

Clinical discussion

People with less severe forms of sacral agenesis can live a normal life, and it is not connected with cognitive impairment; however, concomitant bladder, colon, and lower limb disorders cause considerable morbidity. The majority of treatment is supportive, frequently requiring orthopedic, urological, gastroenterological, pediatric, and physiotherapy support.

Conclusion

Genetic and prepregnancy counseling, as well as early screening of high-risk mothers, remain the only options for prevention of the disease since treatment is mostly supportive.

MNX1 mutations causing neonatal diabetes: Review of the literature and report of a case with extra-pancreatic congenital defects presenting in severe diabetic ketoacidosis

The MNX1 gene encodes a homeobox transcription factor found to be important for pancreatic beta cell differentiation and development. Mutations of the MNX1 gene that cause permanent neonatal diabetes mellitus (PNDM) are rare and have been reported in only two cases. Both cases presented with hyperglycemia, with one case having isolated PNDM while the other had PNDM and multiple neurologic, skeletal, lung, and urologic congenital anomalies resulting in death in early infancy. We describe the genetic and clinical features of a preterm male infant with a homozygous [c.816C > A p.(Phe272Leu)] MNX1 mutation. Our proband is the first case to present in severe diabetic ketoacidosis (DKA), indicating severe insulin deficiency. Unlike the previously reported female case who had the same mutation and presented with isolated PNDM, our proband had hypospadias and congenital umbilical hernia and showed poor growth on follow up. Our case suggests that MNX1 mutations causing NDM can result in a range of extra-pancreatic features and a variable phenotype, similar to other transcription factors causing NDM such as GATA6 and GATA4 mutations. We also cannot exclude the possibility of sex-biased expression of MNX1 gene (which was recently reported for other monogenic/neonatal diabetes genes such as the NEUROD1 and HNF4A in humans) since the two male cases had associated multiple anomalies while the female case had isolated PNDM. Our report further defines the phenotype caused by recessive homozygous MNX1 mutations and explores potential new mechanisms regulating MNX1 gene expression which should be further explored.

Selection of operative approach in children with Currarino syndrome

PURPOSE

To summarize the experience of surgical treatment of children diagnosed with Currarino syndrome, with an emphasis on the selection of an optimal operative approach.

METHODS

The clinical materials of patients diagnosed with Currarino syndrome were recorded. Special attention was given to the operative management, particularly the different routes for operation. The type of ARM was the critical point. The Rintala score was used for the evaluation of bowel function.

RESULTS

The medical records of 26 patients were reviewed. Seven were male, and 19 were female, with a mean age of 19.38 ± 13.80 months. The standard posterior sagittal approach (SPS) group included three perineal fistulae, one anal stenosis, one retraction of the rectum after anoplasty for vestibular fistula, one ARM with no fistula, one rectourethral fistula, and one cloaca. In the limited posterior sagittal approach (LPS) group, there were 13 perineal fistulae, one displacement of the rectum, and one retraction of the rectum after anoplasty for the vestibular fistula. In addition, the transanal approach (TA) and anterior sagittal approach (AS) were also used. The mean follow-up time was 39.48 ± 26.84 m. The Rintala score was 16.74 ± 2.93.

CONCLUSION

For a perineal fistula, SPS or LPS should be used to reach anoplasty and remove the presacral mass. For a vestibular fistula, the AS or LPS should be chosen. For anal stenosis, SPS or LPS should be used.

Postoperative complications and long-term outcomes in Currarino syndrome

PURPOSE

This study aimed to present ten cases of Currarino syndrome, study their postoperative complications and prognosis, and analyze whether patient background and clinical factors influenced outcomes.

METHODS

Ten patients with Currarino syndrome who were followed up at our institution between 2004 and 2020 were enrolled. Patient records were retrospectively reviewed for clinical details, postoperative complications, and long-term outcomes.

RESULTS

The incidence of early postoperative complications was 80%, most of which were transient dysuria. The dysuria significantly developed in the higher normal sacral vertebra (p = 0.024) and the complete type of Currarino syndrome (p = 0.033). Later, intractable constipation requiring rectal irrigation and intractable dysuria requiring clean intermittent catheterization occurred in 40% and 30% of the patients, respectively. There was a tendency for tethered cord syndrome (p = 0.076), and the height of the normal sacral vertebra (p = 0.071) was related to intractable constipation. The height of the normal sacral vertebra (p = 0.05) and the tumor size on the image (p = 0.012) were significantly higher and larger, respectively, in the group with intractable dysuria than in the group without intractable dysuria.

CONCLUSION

Postoperative complications, especially early ones, occur at a high rate. Long-term intractable constipation and dysuria may be influenced by the degree of sacral dysplasia.

Familial tendency in patients with lipoma of the filum terminale

PURPOSE

Lipoma of the filum terminale (FL) is an abnormality in which fat is deposited in the filum terminale. This lipoma is often detected by skin abnormalities in the lumbosacral area such as a sacrococcygeal dimple. Some cases may develop tethered cord and become symptomatic. However, the genetic basis of FL is still unclear.

METHODS

This study aimed to determine whether there was a family history of FL or other forms of spina bifida among 54 families of 56 patients with FL and to examine whether there is a familial predisposition in FL. In addition, sex, age at diagnosis, presence of symptoms, presence of sacrococcygeal dimple, and the level of conus medullaris between familial and spontaneous cases were evaluated.

RESULTS

Of the 54 families of FL patients, there were 48 siblings. Among the 48 siblings, 2 had "occult" FL. The frequency of FL among siblings was estimated to be 4.2% (2/48), which was significantly higher than the sum of previously reported cases of spontaneous FL (0.91%; p = 0.017). However, there was no significant difference in sex, age at diagnosis, presence of symptoms, presence of sacrococcygeal dimple, diameter of filum terminale, or level of conus medullaris between familial and spontaneous cases.

CONCLUSION

To our knowledge, this is the first report on familial FL and examination of the frequency of FL among siblings. The high probability of FL among siblings of FL patients suggests that genetic factors may play a role in FL development.

Currarino syndrome: a comprehensive genetic review of a rare congenital disorder

Background

The triad of a presacral mass, sacral agenesis and an anorectal anomaly constitutes the rare Currarino syndrome (CS), which is caused by dorsal–ventral patterning defects during embryonic development. The major causative CS gene is MNX1, encoding a homeobox protein.

Main body

In the majority of patients, CS occurs as an autosomal dominant trait; however, a female predominance observed, implies that CS may underlie an additional mode(s) of inheritance. Often, the diagnosis of CS is established solely by clinical findings, impacting a detailed analysis of the disease. Our combined data, evaluating more than 60 studies reporting patients with CS-associated mutations, revealed a slightly higher incidence rate in females with a female-to-male ratio of 1.39:1. Overall, MNX1 mutation analysis was successful in only 57.4% of all CS patients investigated, with no mutation detected in 7.7% of the familial and 68% of the sporadic patients. Our studies failed to detect the presence of an expressed MNX1 isoform that might explain at least some of these mutation-negative cases.

Conclusion

Aside from MNX1, other genes or regulatory regions may contribute to CS and we discuss several cytogenetic studies and whole-exome sequencing data that have implicated further loci/genes in its etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01799-0.

Evaluating the Clinical Utility of Genome Sequencing for Cytogenetically Balanced Chromosomal Abnormalities in Prenatal Diagnosis

Balanced chromosomal abnormalities (BCAs) are changes in the localization or orientation of a chromosomal segment without visible gain or loss of genetic material. BCAs occur at a frequency of 1 in 500 newborns and are associated with an increased risk of multiple congenital anomalies and/or neurodevelopmental disorders, especially if it is a de novo mutation. In this pilot project, we used short read genome sequencing (GS) to retrospectively re-sequence ten prenatal subjects with de novo BCAs and compared the performance of GS with the original karyotyping. GS characterized all BCAs found by conventional karyotyping with the added benefit of precise sub-band delineation. By identifying BCA breakpoints at the nucleotide level using GS, we found disruption of OMIM genes in three cases and identified cryptic gain/loss at the breakpoints in two cases. Of these five cases, four cases reached a definitive genetic diagnosis while the other one case had a BCA interpreted as unknown clinical significance. The additional information gained from GS can change the interpretation of the BCAs and has the potential to improve the genetic counseling and perinatal management by providing a more specific genetic diagnosis. This demonstrates the added clinical utility of using GS for the diagnosis of BCAs.

Currarino syndrome in an elderly man: Multimodality imaging findings

Currarino syndrome is a rare congenital disorder characterized by the triad of anorectal anomalies, sacrococcygeal dysgenesis and presacral mass. Because of the anorectal anomalies, the extrinsic compression due to the presacral mass and neurologic deficits, patients usually present with gastrointestinal symptoms, most commonly chronic constipation. Most cases of Currarino syndromes are diagnosed in childhood, at birth or in the pre-birth period and, even if adult presentation has been reported in few sporadic case reports, the diagnosis in the late stages of life remains extremely rare. In this paper, we describe the imaging findings of an elderly man with a past medical history of megacolon surgically treated in his childhood, who was diagnosed with Currarino syndrome at the age of 72.

Currarino Syndrome: A Rare Condition With Potential Connection to Neuroendocrine Tumors

OBJECTIVES

Currarino syndrome (CS) is a congenital disorder that consists of a triad of anomalies: presacral mass, sacral dysgenesis, and anorectal malformations. Few cases of CS with neuroendocrine tumors (NETs) have been reported. In this study, we sought to determine the prevalence and characteristics of NET in patients with CS.

METHODS

Mayo Clinic electronic medical records were searched for patients with CS. Data on demographics, CS diagnosis, family history, genetic testing, and NET diagnosis were extracted.

RESULTS

A total of 26 patients with CS were identified with 3 (11.5%) of them having an additional diagnosis of NET. Three patients had a family history of NET (11.53%), and 7 patients had a family history of CS (26.9%). Of the 3 NET/CS patients, 2 had a confirmed primary NET from the presacral mass, with the third patient demonstrating focal uptake on the somatostatin receptor imaging within the presacral. Two patients received octreotide, followed by peptide receptor radionuclide therapy. The other patient was not treated because of complete resection of presacral mass and is currently undergoing surveillance scans.

CONCLUSIONS

In our patients with CS, the prevalence of NET is 11.53%. The coexistence of 2 rare conditions, CS and presacral NET, suggests that there may be an etiological connection.

Novel MNX1 mutations and genotype-phenotype analysis of patients with Currarino syndrome

Background

Currarino syndrome (CS) is a specific complex of congenital caudal anomalies, including anorectal malformations, presacral mass and sacral anomalies. Mutations in the MNX1 gene are closely related to CS and occur in almost all familial cases and less than half of sporadic patients. We investigated the spectrum of MNX1 pathogenic variants and associated clinical features in Chinese patients with CS.

Results

Seventeen index patients from 16 families were recruited from 2015 to 2018. All patients were diagnosed with CS and treated at the Capital Institute of Pediatrics Affiliated Children’s Hospital. Genetic testing was applied to identify mutations in CS patients and their relatives by whole-exome sequencing and Sanger sequencing. Functional verification was performed for a recurrent noncanonical splice site variant in MNX1 with a minigene splicing assay. In 17 CS patients, 14 were complete CS and 3 were mild CS. Nine variants in MNX1 were identified in 11 patients, and these included two frameshift mutations (p.Leu223Leufs*61, p.X402Serfs*70), four nonsense mutations (p.Gly42X, p.Cys88X, p.Gln24X, p.Cys241X), one missense mutation (p.Trp288Leu), one splice region variant (c.691 + 3G > T) and one polyalanine polymorphism (p.Ala135insAlaAla). Seven of these nine variants have never been reported. Pathogenic MNX1 mutations were found in 100% (4/4) of familial and 46% (6/13) of sporadic patients.

Conclusion

Our study expanded the mutation spectrum of MNX1 and provided clinical and genetic analyses of seventeen CS patients from mainland China.

Laparoscopic-Assisted Anorectal Pull-Through for Currarino Syndrome

Objective: Currarino syndrome (CS) is characterized by the triad of sacral anomalies, presacral tumor, and anorectal malformation (ARM). This study evaluates the feasibility and outcomes of laparoscopic-assisted anorectal pull-through (LAARP) for CS. Materials and Methods: Children admitted for primary or redo repair of CS through LAARP between 2016 and 2019 were reviewed. The indication of redo included constipation with megarectosigmoid, residual presacral mass, anastomosis leak, and secondary fistula. ARM was corrected by excision of rectal stenosis, fistula, and its associated megarectosigmoid. This was followed by a complete surgical resection of the presacral tumor, with subsequent pull-through and anocolic anastomosis. This was done with a combined laparoscopic and transanal approach. The detailed surgical techniques, early postoperative complications, and mid-term functional outcomes were summarized. Results: Fourteen patients underwent LAARP for primary (N = 4) and redo (N = 10) repair of CS. Four of them had colostomy previously. Mean age at operation was 20.7 ± 13.9 months. Mean operative time was 120 ± 25 minutes. Median hospital stay was 8 days (range 7-9 days) postoperatively. None of the patients developed early postoperative complications such as anastomotic leaks, presacral abscesses, recurrent fistulas, and residual mass. Bowel function was assessed 1 year after LAARP in 10 patients. Mean follow-up time was 15.9 months. The frequency of bowel movements was 3.3 ± 1.5/day. Constipation occurred in 2 patients. Occasional soiling (<3 times/week) was reported in 4 patients and frequent soiling (>3 times/week) was in 1. Conclusion: LAARP for CS is safe and effective.

Currarino syndrome presenting as a cerebrospinal fluid leak from the dermal sinus tract: case report

Currarino syndrome is an autosomal dominant condition with variable expressivity and penetrance that is associated with several classic features: sacral dysgenesis, presacral mass, and/or anorectal anomalies. The authors present a unique case in which the patient's initial presentation was a CSF leak from a sinus tract. The sinus tract was identified and disconnected from the thecal sac, obliterating the anterior sacral meningocele. This case represents a unique scenario in which Currarino syndrome manifested as a CSF leak from a dermal sinus tract.

Neurosurgical management of Currarino syndrome: A case series and review of literature

Background

The Currarino syndrome (CS), defined by the triad of anorectal malformations, sacral bone deformities, and presacral masses, is rare. There are few surgical series that discuss conservative management versus the surgical approaches to these lesions. Here, we describe utilizing a combined anterior and posterior approach for resecting these lesions in four patients.

Methods

Four patients with CS were treated with two-stage approaches performed by a multidisciplinary team, including pediatric neurosurgery and general surgery. The first anterior laparoscopic approach mobilized the presacral mass from its ventral attachments. The second posterior procedure detethered the spinal cord, repaired the dural defect, and facilitated removal of the presacral mass.

Results

Gross total resection of all four presacral masses was accomplished without intraoperative complication; all patients clinically improved.

Conclusion

The CS is characterized by a large presacral mass. Here, one must rule out malignancy and also consider diagnosis/resection due to the risks for malignant transformation. The operative approach we described in four patients utilized standard anterior mobilization of the mass, followed by posterior detethering, dural repair, and ultimate resection.

Descriptive and risk factor analysis of nonsyndromic sacral agenesis: National Birth Defects Prevention Study, 1997-2011

Sacral agenesis is a rare birth defect characterized by partial or complete absence of the sacrum. We sought to (a) describe case characteristics, (b) estimate birth prevalence, and (c) identify risk factors for nonsyndromic sacral agenesis using data from the National Birth Defects Prevention Study (NBDPS). The NBDPS was a population-based, case-control study involving pregnancies with estimated dates of delivery from October 1997 through December 2011. We estimated birth prevalence using all NBDPS eligible cases. Using self-reported maternal exposure information, we conducted multivariable logistic regression analysis to identify potential risk factors overall and among women without diabetes. The birth prevalence of sacral agenesis was 2.6/100,000 live births. In the multivariable analysis, multifetal pregnancy, pre-existing Type 1 diabetes, and pre-existing Type 2 diabetes were positively and significantly associated with sacral agenesis, albeit estimates were imprecise. Preexisting Type 1 diabetes was the strongest risk factor (adjusted odds ratio = 96.6, 95% confidence interval = 43.5-214.7). Among women without diabetes, periconceptional smoking was positively and significantly associated with sacral agenesis. Our findings underscore the importance of smoking cessation programs among women planning pregnancy and the importance of better understanding the role of glycemic control before and during pregnancy when designing interventions for primary prevention of sacral agenesis.

Successful Management of a Giant Anterior Sacral Meningocele Associated with Low-Dysplastic Spondylolisthesis from a Single Posterior Approach: Case Report

BACKGROUND

Anterior sacral meningocele (ASM) is characterized by a herniation of the dural sac through a bony defect of the anterior sacral wall. Symptoms of ASMs are usually directly related to their mass effect on the adjacent pelvic structures, often causing chronic constipation and urinary disturbances. The low-dysplastic spondylolisthesis results from congenital abnormalities of the upper sacral facets or the neural arch of L5. Its symptoms are related to neural compression and/or segmental instability. The main aim of this case report is to present a patient who underwent surgery for low dysplastic spondylolisthesis combined with an ASM that were both considered symptomatic.

CASE DESCRIPTION

A 23-year-old male patient, with no medical history, no signs of neurologic deficit was admitted for lower back pain and irritation, numbness and paresthesia in the L5 dermatomes bilaterally, together with alternating constipation and diarrhea with no response to conservative treatment. Computed tomography and magnetic resonance imaging of the lumbar spine and pelvis showing a large retroperitoneal mass with fluid contend causing compression and displacement of the pelvic structures, in particular the bladder and the colon and there was also a low-dysplastic spondylolisthesis of L5/S1 with pressure on both L5 nerve roots. Surgery was done in one session purely from a posterior approach with no complications.

CONCLUSIONS

In the present case, we have demonstrated the suitability of a standard midline posterior approach in the treatment not only for ASM itself, but also for a low-dysplastic spondylolisthesis in 1 session.

Currarino syndrome: repair of the dysraphic anomalies and resection of the presacral mass in a combined neurosurgical and general surgical approach

OBJECTIVEIt is well established that Currarino syndrome (CS) may be associated with spinal dysraphism. Here, the authors report on 10 CS patients with dysraphic anomalies who had undergone a combined neurosurgical and general surgical approach to repair the dysraphic anomalies and resect the presacral mass in a single operation. They discuss the spectrum of spinal dysraphism that may coexist in CS in the context of its developmental etiology.METHODSChildren with a confirmed CS diagnosis who had undergone the combined operative approach were identified from a departmental database. Presenting features were recorded and preoperative imaging was analyzed to record features of the presacral mass and the dysraphic anomalies. The histopathological nature of the resected presacral mass and the outcomes postoperatively and at the last follow-up were reviewed.RESULTSBetween 2008 and 2015, 10 patients presented with CS, 9 with constipation. Median age at the time of surgery was 1.3 years. Six of the 10 patients had anorectal malformation consisting of anal stenosis, rectal stenosis, or imperforate anus. Spinal anomalies included anterior meningocele (5 cases), low-lying conus (8), terminal syrinx (4), fatty filum (5), caudal lipoma (3), and intraspinal cyst (1). In all cases, the lumbosacral spinal canal was accessed via a midline approach with laminoplasty, allowing spinal cord untethering and repair of the dysraphic anomalies. Following dural closure, the incision was extended inferiorly to incorporate a posterior sagittal approach to resect the presacral mass. The histopathological nature of the mass was mature teratoma (8 cases), complex hamartomatous malformation (1), or neurenteric cyst (1). There were no new instances of neurological deterioration, with most instances of persisting morbidity related to constipation (6 cases) or neurogenic bladder dysfunction (8). There were no infective complications, no instances of cerebrospinal fluid fistula, no recurrences of the presacral mass, and no cases of retethering of the spinal cord.CONCLUSIONSAlthough not part of the original triad, spinal dysraphic anomalies are common in CS and in keeping with a disorder of secondary neurulation. Lumbosacral MRI is an essential investigation when CS is suspected. Children are at risk of sphincter impairment due to the anorectal malformation; however, both spinal cord tethering and compression from the presacral mass may further compromise long-term continence. A combined operative approach to repair the dysraphic anomalies and resect the presacral mass is described with good postoperative and long-term outcomes.

Spectrum of MNX1 Pathogenic Variants and Associated Clinical Features in Korean Patients with Currarino Syndrome

Background

The major genetic cause of Currarino syndrome (CS), a congenital malformation syndrome typically characterized by sacral agenesis, anorectal malformation, and presence of a pre-sacral mass, is known to be pathogenic variants in motor neuron and pancreas homeobox 1 (MNX1), which exist in almost all familial cases and 30% of sporadic cases. Less commonly, a large deletion or a complex rearrangement involving the 7q36 region is associated with CS. We investigated the spectrum of MNX1 pathogenic variants and associated clinical features in the Korean patients with CS.

Methods

We enrolled 25 patients with CS, including 24 sporadic cases and one familial case. Direct sequencing of MNX1 and multiplex ligation-dependent probe amplification were performed. We also analyzed clinical phenotypes and evaluated genotype-phenotype correlations.

Results

We identified six novel variants amongst a total of six null variants, one missense variant, and one large deletion. The null variants included four frameshift variants (p.Gly98Alafs^*124, p.Gly145Alafs^*77, p.Gly151Leufs^*67, and p.Ala216Profs^*5) and two nonsense variants (p.Tyr186^* and p.Gln212^*). The missense variant, p.Lys295Gln, was located in the highly-conserved homeobox domain and was predicted to be deleterious. A large deletion involving the 7q36 region was detected in one patient. Pathogenic variants in MNX1 were detected in 28% of all CS cases and 25% of sporadic cases. The clinical phenotype was variable in patients with and without pathogenic variants; no significant genotype-phenotype correlation was observed.

Conclusions

This study revealed the spectrum and phenotypic variability of MNX1 pathogenic variants in the Korean population.

How to Explore Fetal Sacral Agenesis Without Open Dysraphism: Key Prenatal Imaging and Clinical Implications

The estimated prevalence of fetal caudal dysgenesis is 1 per 100,000 births. The functional prognosis of sacral agenesis is dominated by the large spectrum of associated caudal malformations. Except for cases associated with hydrocephalus secondary to open spinal dysraphism or chromosomal anomalies, association with mental deficiency is rare. We propose a systematic prenatal approach to cases of fetal sacral agenesis based on 9 etiologic items: clinical context, type of sacral dysgenesis, associated spinal cord malformations, mobility of lower limbs, investigation of the presacral region, analysis of the gastrointestinal tract, analysis of the genitourinary tract, associated vertebral defects, and cytogenetic analysis.

Currarino syndrome and microcephaly due to a rare 7q36.2 microdeletion: a case report

Background

Currarino syndrome is a rare condition characterized by presacral mass, anorectal malformation and sacral dysgenesis.

Case presentation

We report the case of a child that presented chronic constipation, encopresis and mycrocephaly. The characteristics were initially compatible with a case of functional constipation and a therapy with polyethylene glycol was prescribed. After a year, because of poor response, a plain abdominal X-ray was performed, detecting sacrum abnormalities. Finally, a CGH-array analysis was performed and a form of Currarino Syndrome caused by a rare 7q36 microdeletion, was diagnosed.

Conclusion

Occult spinal dysraphism should be suspected in case of poor polyethylene glycol responder constipation, even when evident sacral abnormalities on the physical examination are not detected.

Whole exome sequencing of sporadic patients with Currarino Syndrome: A report of three trios

Currarino Syndrome is a rare congenital malformation syndrome described as a triad of anorectal, sacral and presacral anomalies. Currarino Syndrome is reported to be both familial and sporadic. Familial CS is today known as an autosomal dominant disorder caused by mutations in the transcription factor MNX1. The aim of this study was to look for genetic causes of Currarino Syndrome in sporadic patients after ruling out other causes, like chromosome aberrations, disease-causing variants in possible MNX1 cooperating transcription factors and aberrant methylation in the promoter of the MNX1 gene. The hypothesis was that MNX1 was affected through interactions with other transcription factors or through other regulatory elements and thereby possibly leading to abnormal function of the gene. We performed whole exome sequencing with an additional 6Mb custom made region on chromosome 7 (GRCh37/hg19, chr7:153.138.664-159.138.663) to detect regulatory elements in non-coding regions around the MNX1 gene. We did not find any variants in genes of interest shared between the patients. However, after analyzing the whole exome sequencing data with Filtus, the in-house SNV filtration program, we did find some interesting variants in possibly relevant genes that could be explaining these patients` phenotypes. The most promising genes were ETV3L, ARID5A and NCAPD3. To our knowledge this is the first report of whole exome sequencing in sporadic CS patients.

Comprehensive review of the duplication 3q syndrome and report of a patient with Currarino syndrome and de novo duplication 3q26.32-q27.2

Partial duplications of the long arm of chromosome 3, dup(3q), are a rare but well-described condition, sharing features of Cornelia de Lange syndrome. Around two thirds of cases are derived from unbalanced translocations, whereas pure dup(3q) have rarely been reported. Here, we provide an extensive review of the literature on dup(3q). This search revealed several patients with caudal malformations and anomalies, suggesting that caudal malformations or anomalies represent an inherent phenotypic feature of dup(3q). In this context, we report a patient with a pure de novo duplication 3q26.32-q27.2. The patient had the clinical diagnosis of Currarino syndrome (CS) (characterized by the triad of sacral anomalies, anorectal malformations and a presacral mass) and additional features, frequently detected in patients with a dup(3q). Mutations within the MNX1 gene were found to be causative in CS but no MNX1 mutation could be detected in our patient. Our comprehensive search for candidate genes located in the critical region of the duplication 3q syndrome, 3q26.3-q27, revealed a so far neglected phenotypic overlap of dup(3q) and the Pierpont syndrome, associated with a mutation of the TBL1XR1 gene on 3q26.32.

Parental risk factors of anorectal malformations: Analysis with a regional population-based control group

BACKGROUND

Adequate evidence on environmental risk factors for anorectal malformations (ARMs) is very limited. We assessed maternal body weight and several prenatal exposures of the parents to tobacco, pregestational diabetes, chronic cardiovascular and respiratory diseases, periconceptional folic acid and multivitamin intake.

METHODS

Data from the German Network for Congenital Uro-REctal malformations (CURE-Net) were compared with data from the Malformation Monitoring Centre Saxony-Anhalt of the Otto-von-Guericke University in Magdeburg, Germany. Controls were matched to cases by gender and birth year of the child. Crude and adjusted odds ratios (95% confidence intervals) were calculated for potential risk factors using multivariable logistic regression.

RESULTS

In total, 158 ARM patients and 474 healthy infants born between 1993 and 2008 in Germany were included. Maternal age at birth of ARM cases and birth plurality were significantly higher and gestational age and weight significantly lower compared with controls (p < 0.0001). We observed significantly increased risks for ARMs associated with maternal smoking before conception and the first trimester of pregnancy (odds ratio = 2.23, 95% confidence interval 1.04-4.79, p = 0.039) and maternal chronic respiratory diseases (odds ratio = 29.25, 95% confidence interval 8.22-104.14, p < 0.0001). No statistically significant increased risk or protective effect was found for the other investigated factors.

CONCLUSION

This study suggests an association between the occurrence of ARMs in the offspring and periconceptional maternal smoking as well as maternal chronic respiratory diseases. In addition, there might be a sign of an association for maternal diabetes, although not statistically significant. It can be assumed that the power is far too low to provide reliable estimates.

Pronephric tubule morphogenesis in zebrafish depends on Mnx mediated repression of irx1b within the intermediate mesoderm

Mutations in the homeobox transcription factor MNX1 are the major cause of dominantly inherited sacral agenesis. Studies in model organisms revealed conserved mnx gene requirements in neuronal and pancreatic development while Mnx activities that could explain the caudal mesoderm specific agenesis phenotype remain elusive. Here we use the zebrafish pronephros as a simple yet genetically conserved model for kidney formation to uncover a novel role of Mnx factors in nephron morphogenesis. Pronephros formation can formally be divided in four stages, the specification of nephric mesoderm from the intermediate mesoderm (IM), growth and epithelialisation, segmentation and formation of the glomerular capillary tuft. Two of the three mnx genes in zebrafish are dynamically transcribed in caudal IM in a time window that proceeds segmentation. We show that expression of one mnx gene, mnx2b, is restricted to the pronephric lineage and that mnx2b knock-down causes proximal pronephric tubule dilation and impaired pronephric excretion. Using expression profiling of embryos transgenic for conditional activation and repression of Mnx regulated genes, we further identified irx1b as a direct target of Mnx factors. Consistent with a repression of irx1b by Mnx factors, the transcripts of irx1b and mnx genes are found in mutual exclusive regions in the IM, and blocking of Mnx functions results in a caudal expansion of the IM-specific irx1b expression. Finally, we find that knock-down of irx1b is sufficient to rescue proximal pronephric tubule dilation and impaired nephron function in mnx-morpholino injected embryos. Our data revealed a first caudal mesoderm specific requirement of Mnx factors in a non-human system and they demonstrate that Mnx-dependent restriction of IM-specific irx1b activation is required for the morphogenesis and function of the zebrafish pronephros.

Sacral Agenesis with Neurogenic Bladder Dysfunction-A Case Report and Review of the Literature

Sacral agenesis (part of the caudal regression syndrome) is a rare and severe sacral developmental abnormality. It is a congenital malformation of unknown aetiology with possible involvement of genetic and teratogenic factors. It is described by various degrees of developmental failure, the most extreme and rare being sirenomelia or mermaid syndrome. The associated malformations comprise anorectal, vertebral, urological, genital, and lower limb anomalies. Approximately 15-20% mothers of these children have insulin dependent diabetes mellitus. The case is being reported for its rarity and educative value because prognosis is good in isolated sacral agenesis.

Phenotype analysis impacts testing strategy in patients with Currarino syndrome

Currarino syndrome (OMIM 175450) presents with sacral, anorectal, and intraspinal anomalies and presacral meningocele or teratoma. Autosomal dominant loss-of-function mutations in the MNX1 gene cause nearly all familial and 30% of sporadic cases. Less frequently, a complex phenotype of Currarino syndrome can be caused by microdeletions of 7q containing MNX1. Here, we report one familial and three sporadic cases of Currarino syndrome. To determine the most efficient genetic testing approach for these patients, we have compared results from MNX1 sequencing, chromosomal microarray, and performed a literature search with analysis of genotype-phenotype correlation. Based on the relationship between the type of mutation (intragenic MNX1 mutations vs 7q microdeletion) and the presence of intellectual disability, growth retardation, facial dysmorphism, and associated malformations, we propose a testing algorithm. Patients with the classic Currarino triad of malformations but normal growth, intellect, and facial appearance should have MNX1 sequencing first, and only in the event of a normal result should the clinician proceed with chromosomal microarray testing. In contrast, if growth delay and/or facial dysmorphy and/or intellectual disability are present, chromosomal microarray should be the first method of choice for genetic testing.

Malignant transformation in sacrococcygeal teratoma and in presacral teratoma associated with Currarino syndrome: a comparative study

BACKGROUND/PURPOSE

The risk of malignant transformation of sacrococcygeal teratoma (SCT) and of presacral teratoma in Currarino syndrome (CS) may differ despite the similar position and appearance.

METHODS

Malignant transformation and teratoma recurrence were assessed in a national retrospective comparative analysis of 205 SCT and 16 CS patients treated in one of the six pediatric surgical centers in the Netherlands between January 1981 and December 2010.

RESULTS

The malignancy free survival of patients with SCT was lower than for patients with a presacral teratoma associated with CS (80% and 58% after one and two years in SCT versus 100% after two years in CS, p=0.017) CONCLUSIONS: In SCT, malignancy and recurrence risk are high. Therefore, early and complete resection is mandatory. Our data show that the risk of malignant transformation of a presacral teratoma in CS is small.

Urological outcome in patients with Currarino syndrome

INTRODUCTION

Currarino syndrome is a type of caudal regression syndrome characterized by the association of hemisacrum, anorectal malformation and presacral mass. Only few studies on small series report the incidence of urinary dysfunction in Currarino syndrome. Our aim was to evaluate the urological outcome in patients with Currarino syndrome.

PATIENTS AND METHODS

We retrospectively reviewed all Currarino syndrome patients treated in our institution. Of 20 patients, we could evaluate the urological outcome in 16. This group of patients underwent clinical, radiological and urodynamic evaluation.

RESULTS

All 16 patients had a sacral defect, fourteen of them presenting a presacral mass (87.5%), eight a tethered cord (50%), and 7 anorectal malformations (43.7%). Eight patients underwent neurosurgical treatment for neural tube defects. In 14 patients, the presacral mass was resected. One case presented detrusor overactivity, 2 recurrent urinary tract infections and 2 vesicoureteral refluxes. Both patients with lipomyeloschisis had a neuropathic bladder. All the other patients could void the bladder spontaneously. Renal function was normal in all.

CONCLUSION

Currarino syndrome is a rare congenital disorder presenting a variable phenotype. Urological outcome is good in the majority of patients.

Thoracic epidural teratoma: case report and review of the literature

PURPOSE

Spinal teratomas comprise a rare subset of spinal cord tumors, and here, we describe an even rarer childhood thoracic extradural–intracanalicular teratoma. The clinical presentation, management, and pathophysiology of these tumors are reviewed to promote recognition and guide treatment of these lesions.

METHODS

We report the case of a 21-month-old boy who presented with marked spasticity, as well as failure to ambulate and meet motor milestones. Additionally, we provide a literature review of spinal teratomas, including their clinical presentation, work-up, pathophysiology, and underlying genetics.

Results

An MRI of the spine revealed a large dorsal epidural tumor extending from T3 to T10 with heterogeneous contrast enhancement and severe spinal cord compression. The tumor was resected revealing a cystic mass with tissue resembling hair, muscle, as well as cartilage; pathology confirmed the diagnosis of teratoma. Gross total resection was achieved, and the child eventually gained ambulatory function.

CONCLUSIONS

Given that spinal teratomas are rare entities that can present with significant neurologic compromise, they must remain on clinicians’ differentials. Unfortunately, the exact origin of these tumors remains inconclusive and requires further investigation.

Currarino syndrome and spinal dysraphism

Currarino syndrome is a rare constellation of congenital anomalies characterized by the triad of sacral dysgenesis, presacral mass, and anorectal malformation. It is frequently associated with other congenital anomalies, often including occult spinal dysraphism. Mutations in the MNX1 gene are identified in the majority of cases. The authors report a rare case of Currarino syndrome in an infant with tethered cord syndrome and a dorsal lipomyelomeningocele continuous with a presacral intradural spinal lipoma, in addition to an imperforate anus and a scimitar sacrum. They review the literature to highlight patterns of occult spinal dysraphism in patients with Currarino syndrome and their relationship to tethered cord syndrome. Approximately 60% of the patients with Currarino syndrome reported in the literature have an occult spinal dysraphism. Published studies suggest that the risk of tethered cord syndrome may be higher among patients with a lipoma and lower among those with a teratoma or anterior meningocele.

Currarino syndrome at Rikshospitalet 1961-2012

BACKGROUND

Currarino syndrome is a rare hereditary condition with constipation as the main symptom. The typical patient has a combination of sacral, anorectal, intraspinal and presacral anomalies. Familial cases most often have a mutation in the MNX1 gene. The majority of Norwegian Currarino patients are treated at Rikshospitalet. This article gives an account of 50 years of experience with the condition.

MATERIAL AND METHOD

The study is based on the medical records of patients with Currarino syndrome, as well as some first-degree relatives, from the period 1961-2012. We recorded the results of mutation analysis, X-ray of the sacrum, and ultrasound, MRI and/or CT scans, as well as the treatments administered.

RESULTS

We treated 29 patients over the period in question, and in addition identified seven healthy relatives with a mutation in MNX1 and one relative with a pathognomonic sacral anomaly. There were 15 familial and 14 sporadic cases. Fourteen familial cases and one of the sporadic cases were shown to have a mutation in the MNX1 gene. Phenotypic variation was pronounced, and we saw no obvious correlation between genotype and phenotype. Twenty-six of the patients had constipation and 15 underwent a colostomy. Fourteen patients required neurosurgical and seven urogenital interventions. No patients had malignant disease.

INTERPRETATION

Patients with Currarino syndrome have a highly variable clinical presentation with constipation as the main problem. In patients with a familial syndrome, a mutation in the MNX1 gene can be expected.

Dental developmental abnormalities in a patient with subtelomeric 7q36 deletion syndrome may confirm a novel role for the SHH gene

Studies in mice demonstrated that the Shh gene is crucial for normal development of both incisors and molars, causing a severe retardation in tooth growth, which leads to abnormal placement of the tooth in the jaw and disrupted tooth morphogenesis. In humans the SHH gene is located on chromosome 7q36. Defects in its protein or signaling pathway may cause holoprosencephaly spectrum, a disorder in which the developing forebrain fails to correctly separate into right and left hemispheres and that can be manifested in microforms such as single maxillary central incisor. A novel role for this gene in the developing human primary dentition was recently demonstrated. We report a 12-year old boy with a de novo 7q36.1-qter deletion characterized by high-resolution karyotyping, oligonucleotide aCGH and FISH. His phenotype includes intellectual disability, non-verbal communication, hypospadia, partial sacral agenesis and absence of coccyx, which are distinctive features of the syndrome and mainly correlated with the MNX1, HTR5A and EN2 genes. No microforms of holoprosencephaly spectrum were observed; but the patient had diastema and dental developmental abnormalities, such as conical, asymmetric and tapered inferior central incisors. The dental anomalies are reported herein for the first time in subtelomeric 7q36 deletion syndrome and may confirm clinically a novel role for the SHH gene in dental development.

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We report a boy with 7q-, dental developmental abnormalities and sacral agenesis.

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We propose novel roles for SHH gene related to dental developmental abnormalities.

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The MNX1 gene may be associated with caudal deficiency sequence in 7q- patients.

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HTR5A and EN2 may be related to abnormal brain development in 7q- patients.

"This bicycle gives me a headache", a congenital anomaly

Backround

The combination of a presacral mass, a sacral bone deformity, and an anorectal malformation are also known as the Currarino triad or Currarino syndrome. The syndrome is associated with a very high rate of severe and intractable constipation and urinary incontinence. However, it can also result in less common complaints and symptoms. Although the syndrome is known since 1981 and the involved genes are clarified to a great extent, the diagnosis may be delayed or missed if unrecognized.

Case presentation

A 24-year old female presented with periodical headaches. She was born with an imperforate anus, absent rectum and colon, double bladder, and sacral defect. Soon after birth she underwent several surgical procedures for anorectal and bladder reconstructions. The patient now came to her pediatric urologist for urinary incontinence and mentioned severe headaches on the side, particularly when riding a bike. Finally, she solved her headache problem by stopping to ride her bicycle.

On physical examination no abnormalities were found except the ileostomy that was present ever since soon after birth and her urinary incontinence. Blood tests showed no abnormalities. Additional MRI showed a large and previously not known anterior meningocele at the level of the sacrum. Surgical treatment consisted of closure of the dura by posterior approach.

Conclusion

In this case report we describe the late discovery with an atypical presentation of an anterior meningocele in a young adult with urinary incontinence, a sacral defect, an anorectal malformation and headaches during bicycle riding. After surgical treatment of our patient the meningocele regressed. Three months after successful surgery she had no complaints and was able to ride a bike again.

Currarino Syndrome and HPE Microform Associated with a 2.7-Mb Deletion in 7q36.3 Excluding SHH Gene

Holoprosencephaly (HPE) is the most common forebrain defect in humans. It results from incomplete midline cleavage of the prosencephalon and can be caused by environmental and genetic factors. HPE is usually described as a continuum of brain malformations from the most severe alobar HPE to the middle interhemispheric fusion variant or syntelencephaly. A microform of HPE is limited to craniofacial features such as congenital nasal pyriform aperture stenosis and single central maxillary incisor, without brain malformation. Among the heterogeneous causes of HPE, point mutations and deletions in the SHH gene at 7q36 have been identified as well as extremely rare chromosomal rearrangements in the long-range enhancers of this gene. Here, we report a boy with an HPE microform associated with a Currarino syndrome. Array CGH detected a de novo 2.7-Mb deletion in the 7q36.3 region including the MNX1 gene, usually responsible for the Currarino triad but excluding SHH, which is just outside the deletion. This new case provides further evidence of the importance of the SHH long-range enhancers in the HPE spectrum.

[Anorectal malformations]

Anorectal malformations (ARM) are the result of an abnormal development of the terminal part of the digestive tract interesting anus and/or rectum that occur early between the sixth and tenth week of embryonic development. They carry a malformation spectrum of severity depending on the level of disruption of the anorectal canal and of the associated caudal malformations (sacrum and spine). ARM are associated in over half the cases with other malformations that can be integrated in some cases in known syndromes. If surgical treatment to restore anatomy as normal as possible is indispensable, post-operative care is essential for these patients whose defecation mechanisms are altered, to reach if not continence, at least a socially acceptable cleanliness.

Surgical resection of retrorectal tumours in adults: long-term results in 47 patients

AIM

Retrorectal tumours (RT) are uncommon, and diagnosis and management remain difficult. The aim of this study was to evaluate the results of the surgical management of RT in our institution.

METHOD

Medical notes of all patients operated on for RT were reviewed. Clinical, radiological, surgical, histological data as well as morbidity and long-term results were noted.

RESULTS

Forty-seven patients [34 women (72%), mean age 45.8 (range 17-85) years] underwent surgery for RT between 1997 and 2011. The commonest symptoms were pain (n = 31) and suppuration (n = 10). Thirty-nine (83%) patients underwent preoperative magnetic resonance imaging (MRI). Malignant lesions exhibited typical characteristics on MRI including heterogeneity (n = 5, 83%), solid appearance (n = 4, 67%), a low-T1 signal and high-T2 intensity (n = 5, 83%), enhancement after gadolinium injection (n = 5, 83%), irregular margin (n = 4, 67%) and extension above S3 (i = 5, 83%). A Kraske approach was used in 42 (89%) patients with resection of the coccyx in 25 (60%) and an abdominal or combined approach for the remaining five. Four patients developed complications (two haematoma, two abscess), but only one (haematoma) required reoperation. Histological examination showed 38 (80.9%) benign lesions. After a median follow-up of 71 (2-168) months, 5-year disease-free survival was 75% for malignant lesions and 93.1% for benign lesions (P = 0.023). Four (4/42; 9.5%) patients had moderate perineal pain after a Kraske approach, while no anal dysfunction was seen.

CONCLUSION

Magnetic resonance imaging was the most helpful investigation for retrorectal tumours. The posterior trans-sacrococcygeal approach is the procedure of choice for complete resection for most, especially for benign and cystic lesions without extension above S2.

Next-generation sequencing identifies the Danforth's short tail mouse mutation as a retrotransposon insertion affecting Ptf1a expression

The semidominant Danforth's short tail (Sd) mutation arose spontaneously in the 1920s. The homozygous Sd phenotype includes severe malformations of the axial skeleton with an absent tail, kidney agenesis, anal atresia, and persistent cloaca. The Sd mutant phenotype mirrors features seen in human caudal malformation syndromes including urorectal septum malformation, caudal regression, VACTERL association, and persistent cloaca. The Sd mutation was previously mapped to a 0.9 cM region on mouse chromosome 2qA3. We performed Sanger sequencing of exons and intron/exon boundaries mapping to the Sd critical region and did not identify any mutations. We then performed DNA enrichment/capture followed by next-generation sequencing (NGS) of the critical genomic region. Standard bioinformatic analysis of paired-end sequence data did not reveal any causative mutations. Interrogation of reads that had been discarded because only a single end mapped correctly to the Sd locus identified an early transposon (ETn) retroviral insertion at the Sd locus, located 12.5 kb upstream of the Ptf1a gene. We show that Ptf1a expression is significantly upregulated in Sd mutant embryos at E9.5. The identification of the Sd mutation will lead to improved understanding of the developmental pathways that are misregulated in human caudal malformation syndromes.

Birth defects are the leading cause of infant mortality in the United States, accounting for 1 in 5 infant deaths annually. Birth defects that affect development of the caudal portion of the embryo can include malformations of the spine, such as spina bifida, and malformations of the kidneys and lower gastrointestinal tract. Little is known regarding the genetic causes of human caudal birth defects. The Danforth's short tail (Sd) mouse shares many similarities with these caudal birth defects that occur in humans. In this manuscript, we used next-generation sequencing to identify the genetic cause of the Sd mouse phenotype. We found that the Sd mutation is a retrotransposon insertion that inappropriately turns on a nearby gene that is normally important for pancreas development. Future studies of Sd mice will help us understand the pathogenesis of caudal birth defects in humans.

A 5.8 kb deletion removing the entire MNX1 gene in a Norwegian family with Currarino syndrome

Currarino syndrome (CS) is a clinically variable disorder characterized by anorectal, sacral and presacral anomalies. It is associated with loss-of-function mutations in the motor neuron and pancreas homeobox 1 (MNX1) gene. Inheritance is autosomal dominant, expression variable and penetrance incomplete. We describe a Norwegian family with typical CS in which a heterozygous deletion removes the entire MNX1 gene but no other known genes. We also report MNX1 mutations in three other Norwegian families and confirm that the GCC12 repeat (c.373_375[12]) is a normal allelic variant. This work underscores the importance of dosage analysis of MNX1 when Sanger sequencing is negative.

Presacral teratoma in a Curarrino syndrome woman with an unreported insertion in MNX1 gene

OBJECTIVE

Currarino syndrome (CS) comprises a presacral mass, anorectal malformation, and a sacral bony defect. It is rarely reported in the gynecological field.

CASE REPORT

We describe here the case of a 26-year-old married woman with Currarino syndrome who presented with a presacral teratoma and a previously unreported insertion in MNX1 gene. She had had a pelvic teratoma diagnosed by laparoscopy 8 years previously. She was referred to our clinic because of the increasing size of the teratoma and associated compression symptoms. Computed tomography demonstrated a heterogeneous 12 cm mass in the presacral region. Spina bifida at S2eS5 was also noted. Laparotomy confirmed the diagnosis of presacral teratoma. Genetic analysis disclosed a triple CGC repeat insertion in exon 1 of MNX1, resulting in three in-frame shifts encoding for the amino acid alanine. No siblings had known similar symptoms.

CONCLUSION

Currarino syndrome is known to be an autosomal dominant disorder. The presence of constipation can lead to a diagnosis of the syndrome early in childhood. In sporadic cases diagnosis is late because of atypical symptoms. Delayed treatment of a presacral tumor may cause serious complications such as central nervous system infection or subsequent neurological dysfunction. In clinical practice, a presacral tumor with a sacral bony defect may indicate Currarino syndrome. Genetic analysis of the family may provide information on the hereditary traits of specific MNX1 mutation.

Currarino's triad diagnosed in an adult woman

PURPOSE

To report on a female patient diagnosed with Currarino's triad in adulthood.

CASE REPORT

This case presents an adult patient with a medical history of a congenital anal atresia, a partial sacral agenesis, and a surgically treated ectopic anus. After a coincidentally observed presacral mass by MRI, due to unexplained constipation later in adulthood, Currarino's triad was suspected in this patient. This triad consists of anorectal malformation(s), sacrococcygeal defects and a presacral mass of various origin. Further investigation confirmed the mass to be a meningocele, and showed a tethered cord and a syrinx.

CONCLUSIONS

In (young) patients with anorectal malformations, although having no other symptoms, further examination might be required to exclude Currarino's triad. Importance of early diagnosis and multidisciplinary assessment is recommended to establish adequate treatment if needed.

Zebrafish mnx1 controls cell fate choice in the developing endocrine pancreas

The vertebrate endocrine pancreas has the crucial function of maintaining blood sugar homeostasis. This role is dependent upon the development and maintenance of pancreatic islets comprising appropriate ratios of hormone-producing cells. In all vertebrate models studied, an initial precursor population of Pdx1-expressing endoderm cells gives rise to separate endocrine and exocrine cell lineages. Within the endocrine progenitor pool a variety of transcription factors influence cell fate decisions, such that hormone-producing differentiated cell types ultimately arise, including the insulin-producing beta cells and the antagonistically acting glucagon-producing alpha cells. In previous work, we established that the development of all pancreatic lineages requires retinoic acid (RA) signaling. We have used the zebrafish to uncover genes that function downstream of RA signaling, and here we identify mnx1 (hb9) as an RA-regulated endoderm transcription factor-encoding gene. By combining manipulation of gene function, cell transplantation approaches and transgenic reporter analysis we establish that Mnx1 functions downstream of RA within the endoderm to control cell fate decisions in the endocrine pancreas progenitor lineage. We confirm that Mnx1-deficient zebrafish lack beta cells, and, importantly, we make the novel observation that they concomitantly gain alpha cells. In Mnx1-deficient embryos, precursor cells that are normally destined to differentiate as beta cells instead take on an alpha cell fate. Our findings suggest that Mnx1 functions to promote beta and suppress alpha cell fates.

Currarino Syndroma, initially misdiagnosed and treated like megacolon congenitum

Currarino syndrome was first described as a triad by Guido Currarino, an American radiologist in 1981. It is an autosomal dominant hereditary disease known by the triad of anorectal stenosis, anterior sacral defect, and a presacral mass that is most often an anterior sacral meningocele.

We represent a 3 year boy with refractory constipation from birth, which had been wrongly diagnosed and treated as Hirschsprung’s disease since early childhood. The patient underwent urgent colostomy because of water intoxication due to bowel irrigation, and following investigations (CT, MRI) revealed anorectal anomaly and presacral mass compatible with Curarrino’s syndrome.

Definitive operation was done with perineal approach, posterior sagittal anorectoplasty, with interval colostomy closure 2 months after perineal operation. An uncomplicated postoperative recovery ensued. The patient’s bowel habits successfully returned to normal soon after the operation. A multidisciplinary diagnostic and therapeutic protocol is presented. Main points are rectal examination, sacrum x-Ray, molecular genetic diagnosis, radiologic evaluation of every member of Currarino syndrome families, CT scan, magnetic resonance (MR) evaluation of patient spine and pelvis and suction rectal biopsies. If the mass is a meningocele, colostomy and neurosurgical exploration should precede anoplasty due to the risk of meningitis.