Mutation analysis and embryonic expression of the HLXB9 Currarino syndrome gene

Sacral Agenesis

Sacral agenesis (SA) is a rare congenital neurological disorder characterized by the incomplete development of the sacral spine. This work summarizes the scientific literature on SA, including the following sections: pathogenesis, epidemiology, risk factors, genetics, clinical manifestations, radiological classification, diagnosis, and management. The aim of this work is to provide the most up-to-date and comprehensive medical narrative literature review for this rare congenital disease. This narrative review used PubMed, MEDLINE, Science Direct, and Embase databases. Between December 2022 and September 2023, the following terms were used for the inclusion of original articles: "rare disease," "caudal regression," "diabetic embryopathy," and "sacral agenesis.? The International Sacral Agenesis/Caudal Regression Association participated in reviewing this manuscript and drafting a paragraph on behalf of those living with this condition. The clinical manifestations of SA are heterogeneous. The most prevalent manifestations involve peripheral neurological, motor, urinary, and digestive issues. The prognosis depends on the severity and associated abnormalities. Patients usually exhibit normal mental function but require a multidisciplinary evaluation and largely supportive treatment that enables them to live successful lives. More awareness and research are needed.

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.

Treatment Strategy for Currarino Syndrome Complicated With Anorectal Stenosis

PURPOSE

The present study aimed to review the treatment experience and outcomes of Currarino syndrome (CS) complicated with anorectal stenosis to evaluate the current treatment strategies.

METHODS

Seven cases of CS complicated with anorectal stenosis, treated at our hospital between 1998 and 2021, were retrospectively investigated. This is a case series article from a single institution.

RESULTS

In six and three cases and one case, the presacral mass was a mature teratoma, meningocele, and lipoma, respectively. Resection of the lesion was performed in all six cases of mature teratoma, and duraplasty was performed before resection in all three cases of meningocele. Moreover, surgery for anorectal stenosis was performed simultaneously in four patients. Surgery was performed for six cases of anorectal stenosis, with the remaining case relieved by dilation using a metal bougie. The surgical methods used were a partial resection with end-to-end anastomosis, anorectal strictureplasty, pull-through, posterior sagittal anorectoplasty, and cutback after mass resection. Pathological analysis of the anorectal stenoses revealed disorganized and rough smooth muscle fibers and the replacement of the stroma by an increased quantity of collagen fibers.

CONCLUSIONS

The clinical outcomes of CS can be improved by establishing a treatment flow chart and understanding the complicated pathophysiology of the disease.

Towards clinical applications of in vitro-derived axial progenitors

The production of the tissues that make up the mammalian embryonic trunk takes place in a head-tail direction, via the differentiation of posteriorly-located axial progenitor populations. These include bipotent neuromesodermal progenitors (NMPs), which generate both spinal cord neurectoderm and presomitic mesoderm, the precursor of the musculoskeleton. Over the past few years, a number of studies have described the derivation of NMP-like cells from mouse and human pluripotent stem cells (PSCs). In turn, these have greatly facilitated the establishment of PSC differentiation protocols aiming to give rise efficiently to posterior mesodermal and neural cell types, which have been particularly challenging to produce using previous approaches. Moreover, the advent of 3-dimensional-based culture systems incorporating distinct axial progenitor-derived cell lineages has opened new avenues toward the functional dissection of early patterning events and cell vs non-cell autonomous effects. Here, we provide a brief overview of the applications of these cell types in disease modelling and cell therapy and speculate on their potential uses in the future.

Exome sequencing identifies variants in infants with sacral agenesis

BACKGROUND

Sacral agenesis (SA) consists of partial or complete absence of the caudal end of the spine and often presents with additional birth defects. Several studies have examined gene variants for syndromic forms of SA, but only one has examined exomes of children with non-syndromic SA.

METHODS

Using buccal cell specimens from families of children with non-syndromic SA, exomes of 28 child-parent trios (eight with and 20 without a maternal diagnosis of pregestational diabetes) and two child-father duos (neither with diagnosis of maternal pregestational diabetes) were exome sequenced.

RESULTS

Three children had heterozygous missense variants in ID1 (Inhibitor of DNA Binding 1), with CADD scores >20 (top 1% of deleterious variants in the genome); two children inherited the variant from their fathers and one from the child's mother. Rare missense variants were also detected in PDZD2 (PDZ Domain Containing 2; N = 1) and SPTBN5 (Spectrin Beta, Non-erythrocytic 5; N = 2), two genes previously suggested to be associated with SA etiology. Examination of variants with autosomal recessive and X-linked recessive inheritance identified five and two missense variants, respectively. Compound heterozygous variants were identified in several genes. In addition, 12 de novo variants were identified, all in different genes in different children.

CONCLUSIONS

To our knowledge, this is the first study reporting a possible association between ID1 and non-syndromic SA. Although maternal pregestational diabetes has been strongly associated with SA, the missense variants in ID1 identified in two of three children were paternally inherited. These findings add to the knowledge of gene variants associated with non-syndromic SA and provide data for future studies.

Imaging Review of Obstetric Sequelae of Maternal Diabetes Mellitus

Diabetes mellitus, whether preexisting or gestational, poses significant risk to both the mother and the developing fetus. A myriad of potential fetal complications in the setting of diabetic pregnancies include, among others, congenital anomalies, delayed fetal lung maturity, macrosomia, and increased perinatal morbidity and mortality. Congenital anomalies most commonly involve the nervous, cardiovascular, genitourinary, and musculoskeletal systems. Delayed fetal lung maturity, probably secondary to hyperglycemia suppressing surfactant secretion, is a major determinant of perinatal morbidity and mortality. Besides the potential complications encountered during cesarean delivery in macrosomic fetuses, vaginal delivery is also associated with increased risks of shoulder dystocia, clavicular and humeral fractures, and brachial plexus palsy. Maternal complications are related to the increased risk of hypertensive diseases of pregnancy and associated preeclampsia and hemolysis, elevated liver function, and low platelets (HELLP) syndrome, as well as complications encountered at the time of delivery secondary to fetal macrosomia and cesarean delivery. Additional conditions encountered in the setting of maternal diabetes include polyhydramnios, placental thickening, and two-vessel umbilical cord, each of which is associated with adverse fetal and maternal outcomes including fetal growth restriction, preterm labor, placental abruption, and premature rupture of membranes. Imaging plays a vital role in the evaluation of the mother and the fetus and can provide invaluable information that can be used by maternal fetal medicine to manage this patient population effectively. The authors review the pathophysiologic alterations induced by diabetes in pregnancy, discuss the imaging spectrum of diabetic embryopathy, and provide a detailed review of potential associated maternal complications. Online supplemental material is available for this article. ^©RSNA, 2021.

Multimodality Imaging Evaluation of Fetal Spine Anomalies with Postnatal Correlation

Congenital anomalies of the spine are associated with substantial morbidity in the perinatal period and may affect the rest of the patient's life. Accurate early diagnosis of spinal abnormalities during fetal imaging allows prenatal, perinatal, and postnatal treatment planning, which can substantially affect functional outcomes. The most common and clinically relevant congenital anomalies of the spine fall into three broad categories: spinal dysraphism, segmentation and fusion anomalies of the vertebral column, and sacrococcygeal teratomas. Spinal dysraphism is further categorized into one of two subtypes: open spinal dysraphism and closed spinal dysraphism. The latter category is further subdivided into those with and without subcutaneous masses. Open spinal dysraphism is an emergency and must be closed at birth because of the risk of infection. In utero closure is also offered at some fetal centers. Sacrococcygeal teratomas are the most common fetal pelvic masses and the prognosis is variable. Finally, vertebral body anomalies are categorized into formation (butterfly and hemivertebrae) and segmentation (block vertebrae) anomalies. Although appropriate evaluation of the fetal spine begins with US, which is the initial screening modality of choice, MRI is increasingly important as a problem-solving tool, especially given the recent advances in fetal MRI, its availability, and the complexity of fetal interventions. Online supplemental material is available for this article. ^©RSNA, 2021.

Currarino syndrome or Hirschsprung disease: how to prevent diagnostic dilemma in chronic constipation

Background

Currarino syndrome is a rare congenital malformation having autosomal dominant inheritance. It comprises of anorectal malformation, presacral mass, and sacral vertebral defect occurring in variable proportion. The most common presentation is chronic constipation which is usually due to compression of rectum by anterior sacral mass. If clinical examination is not properly done and digital rectal examination is excluded from the examination, it can be misdiagnosed as other common cause of constipation like Hirschsprung disease.

Case presentation

We are reporting one such case of one-and-half-year-old female child with chronic constipation which was initially managed as Hirschsprung disease, but later on, after a repeat clinical examination with digital rectal examination, it was evaluated on the line of Currarino syndrome. The diagnosis was confirmed by contrast-enhanced computed tomography of abdomen with 3 dimensional reconstruction. It was then managed by posterior sagittal approach with excision of mass and anorectoplasty.

Conclusion

A proper protocol for clinical evaluation of patient with constipation prevents diagnostic dilemma between surgical causes of constipation in pediatric age group. Digital rectal examination must be included in the protocol for evaluation of chronic constipation. In pediatric age group, clinical workup should be done with keeping in mind the rare diagnosis of Currarino syndrome along with common cause of constipation like Hirschsprung disease.

The first case of mosaic MNX1 mutation in an adult female with features of Currarino syndrome

BACKGROUND

Currarino syndrome (CS) is a rare genetic condition characterized by the association of three major clinical signs: anorectal malformation (ARM), sacro-coccygeal bone defects, and presacral mass. Different kinds of ARM can be present such as anteriorly placed anus, imperforate anus, anorectal stenosis, rectal duplication, and fistulae. The presacral mass can be a benign teratoma, a dermoid or neurenteric cyst, anterior meningocele or hamartoma. Females are more frequently affected and usually present with associated gynecologic and urinary tract problems. CS is considered an autosomal dominant trait, with reduced penetrance and variable expressivity. CS is associated with mutations in the MNX1 gene (motor neuron and pancreas homeobox-1, previously known as HLXB9) mapped to chromosome 7q36. Heterozygous loss-of-function mutations in the coding sequence of MNX1 gene have been reported in nearly all familial CS cases and in approximately 30% of CS sporadic patients.

CASE

Here, we present the case of a woman with features of CS carrying a mosaic mutation in the coding region of MNX1 gene. This is the only reported case of a CS diagnosis in which the mutation is present in less than 50% of cells.

CONCLUSION

The lower detection rate of MNX1 mutations in sporadic cases could similarly be explained by somatic mosaicism, mutations occurring outside the coding regions, or genetic heterogeneity.

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.

Presacral neuroendocrine tumors associated with the Currarino syndrome

Currarino syndrome (CS) is an autosomal dominant syndrome caused by mutations in MNX1 and characterized by anorectal abnormalities, partial sacral agenesis, and presacral masses. The presacral masses are typically benign; however, malignant degeneration can occur, and presacral neuroendocrine tumors (NETs) have been reported in six cases. We report three individuals from two families affected by CS in which multiple individuals developed presacral NETs. The first family, 491, had six members with features of CS, including two siblings who presented with presacral, Grade 2 NETs, one of which had metastasized to bone and lymph nodes. A germline c.874C>T (p.Arg292Trp) mutation was found in a highly conserved region of MNX1 in three affected members who underwent sequencing. A second somatic variant/deletion in MNX1 was not detected in either patient's tumor. In the second family, 342, the proband presented with an incidentally discovered presacral NET. The proband's father had previously undergone resection of a presacral NET, and so genetic testing was performed, which did not reveal an MNX1 mutation or copy number variants. The lack of a second, somatic mutation in the tumors from family 491 argues against MNX1 acting as a tumor suppressor, and the absence of a germline MNX1 mutation in family 342 suggests that other genetic and anatomic factors contribute to the development of presacral NETs. These cases highlight the variable presentation of CS, and the potential for malignancy in these patients.

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.

Caudal regression syndrome (Currarino syndrome) with chromosom mutation 9

Currarino syndrome is a rare set of congenital anomalies that include partial sacral agenesis, anorectal anomalies, presacral mass, urogenital malformation, and fistula between pelvic structures. We present a case of a 4-year and 10-month-old boy with incomplete Currarino syndrome, who was born with anus atresia, rectovesical fistula, and permanent perimembranous VSD. At the age of 3, he was diagnosed with neurogenic bladder and sacrococcygeal agenesis. Early psychomotor development was normal.

Cytogenetic GTG-banding test confirmed a male karyotype 46, XY with high heterochromatin in chromosome 9, without mutation of the MNX 1 gene (chromosome 7q36). This genetic analysis is a result of "de novo mutation" or it is the disorder of DNA methylation.

Further genetics analyses like whole-exome sequencing - WES should have been preformed if the test had been availble.

The existence of Currarino syndrome should be suspected among the children born with anorectal malformation. Prompt diagnosis with multidisciplinary monitoring improves the care and quality of life of the patient, reduces morbidity and mortality.

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.

Currarino Triad: Importance of Preoperative Magnetic Resonance Imaging

Currarino triad is a rare syndrome that may be occasionally encountered during managing cases of anorectal anomalies. The triad consists of anorectal anomaly, sacral bony defect, and a presacral mass. It may be familial or sporadic, with a reported female predominance. Identification of the characteristic notched sacrum (sacral scimitar) in plain X-ray (anteroposterior view) is considered the key for the diagnosis; however, not infrequently, this radiological sign is overlooked, especially with a small sacral defect.

Excision of the presacral cyst is usually performed concomitantly during anorectoplasty. The prone position is the standard approach for posterior sagittal anorectoplasty (PSARP) in males; however, in females, the supine position can be used as an alternative (anterior sagittal anorectoplasty). In this case report, excision of the presacral cyst took place in two steps: the first excision during the PSARP procedure in the prone position, and a second operation in the supine lithotomy position to remove a residual component of the lesion that was missed during the primary operation. It was clear that the supine lithotomy position provided better access to explore the presacral space than the prone position, especially with a deeply located cyst as in our case. The role of magnetic resonance imaging (MRI) in the identification of the exact nature and extent of the lesion before surgery is crucial and should be performed in all cases.

Deletions of Chromosome 7q Affect Nuclear Organization and HLXB9Gene Expression in Hematological Disorders

The radial spatial positioning of individual gene loci within interphase nuclei has been associated with up- and downregulation of their expression. In cancer, the genome organization may become disturbed due to chromosomal abnormalities, such as translocations or deletions, resulting in the repositioning of genes and alteration of gene expression with oncogenic consequences. In this study, we analyzed the nuclear repositioning of HLXB9 (also called MNX1), mapping at 7q36.3, in patients with hematological disorders carrying interstitial deletions of 7q of various extents, with a distal breakpoint in 7q36. We observed that HLXB9 remains at the nuclear periphery, or is repositioned towards the nuclear interior, depending upon the compositional properties of the chromosomal regions involved in the rearrangement. For instance, a proximal breakpoint leading the guanine-cytosine (GC)-poor band 7q21 near 7q36 would bring HLXB9 to the nuclear periphery, whereas breakpoints that join the GC-rich band 7q22 to 7q36 would bring HLXB9 to the nuclear interior. This nuclear repositioning is associated with transcriptional changes, with HLXB9 in the nuclear interior becoming upregulated. Here we report an in cis rearrangement, involving one single chromosome altering gene behavior. Furthermore, we propose a mechanistic model for chromatin reorganization that affects gene expression via the influences of new chromatin neighborhoods.

Multiple neurosurgical treatments for different members of the same family with Currarino syndrome

INTRODUCTION

Currarino's syndrome (CS) is an autosomal dominant disorder of embryonic development causing a rare malformating syndrome characterized by a triad of an anorectal malformations, presacral mass (most commonly an anterior sacral meningocele) and sacral bony defects. Mutations of the HLXB9 gene have been identified in most CS cases, but a precise genotype-phenotype correlation has not been described so far. Family screening is obligatory. The diagnosis is usually made during childhood and rarely in adulthood. In this context, imaging, and especially MRI plays a major role in the diagnosis of this syndrome. Surgical management is provided by pediatric surgeons or neurosurgeons.

FAMILIAL CASE REPORT

Here, we present a family case report with CS requiring different neurosurgical management. The son, a 3-year-old boy, developed a tethered spinal cord syndrome associated to a lipoma of the filum terminale, a sacro-coccygeal teratoma and an anal adhesion. A combined surgical approach permitted a good evolution on the urinary and digestive functions despite a persistent fecal incontinence. The 2-year-old daughter presented with a cyst of the thyreoglossal tract infected and fistulized to the skin. She was also followed for a very small lipoma of the filum terminale that required a neurosurgical approach. The father, 44-year-old, manifested functional digestive and urinary disorders caused by a giant anterior sacral meningocele. The ligation of the neck of the cyst and aspiration of the liquid inside in full through a posterior partial approach permit a complete collapse of the cyst with an instantly satisfactory clinical outcome.

CONCLUSION

In these cases, cooperation between pediatric surgeons and neurosurgeons was crucial. The follow-up of these patients should be done in a spina bifida clinic. A geneticist evaluation must be offered to the patient in the case of a CS as well as a clinical evaluation of the relatives (parents, siblings).

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.

A review of genetic factors contributing to the etiopathogenesis of anorectal malformations

BACKGROUND

Anorectal malformation (ARM) is a common congenital anomaly with a wide clinical spectrum. Recently, many genetic and molecular studies have been conducted worldwide highlighting the contribution of genetic factors in its etiology. We summarize the current literature on such genetic factors.

MATERIALS AND METHODS

Literature search was done using different combinations of terms related to genetics in anorectal malformations. From 2012 to June 2017, articles published in the English literature and studies conducted on human population were included.

OBSERVATIONS AND RESULTS

A paradigm shift was observed from the earlier studies concentrating on genetic aberrations in specific pathways to genome wide arrays exploring single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) in ARM patients. Rare CNVs (including 79 genes) and SNPs have been found to genetically contribute to ARM. Out of disrupted 79 genes one such putative gene is DKK4. Down regulation of CDX-1 gene has also been implicated in isolated ARM patients. In syndromic ARM de novo microdeletion at 17q12 and a few others have been identified.

CONCLUSION

Major genetic aberrations proposed in the pathogenesis of ARM affect members of the Wnt, Hox (homebox) genes, Sonic hedgehog (Shh) and Gli2, Bmp4, Fgf and CDX1 signalling pathways; probable targets of future molecular gene therapy.

Multidisciplinary surgical treatment of presacral meningocele and teratoma in an adult with Currarino triad

Background:

Currarino syndrome (CS) is a rare genetic condition that presents with the defining triad of anorectal malformations, sacral bone deformations, and presacral masses, which may include teratoma. Neurosurgeons are involved in the surgical treatment of anterior meningoceles, which are often associated with this condition. The accepted surgical treatment is a staged anterior-posterior resection of the presacral mass and obliteration of the anterior meningocele.

Case Description:

This case involved a 36-year-old female who presented with late onset of symptoms attributed to CS (e.g., presacral mass, anterior sacral meningocele, and sacral agenesis). She successfully underwent multidisciplinary single-stage approach for treatment of the anterior sacral meningocele and resection of the presacral mass. This required obliteration of the meningocele and closure of the dural defect. One year later, her meningocele had fully resolved.

Conclusion:

While late presentations with CS are rare, early detection and multidisciplinary treatment including single-state anterior may be successful for managing these patients.

Currarino Syndrome in a Fetus, Infant, Child, and Adolescent: Spectrum of Clinical Presentations and Imaging Findings

In 1981, Currarino et al described a triad of findings that consist of partial sacral dysgenesis, presacral mass (anterior meningocele, enteric cyst, or presacral teratoma) and anorectal malformation. Currarino syndrome exhibits variable expressivity and the clinical presentation tends to vary with the age of the subject such as spinal anomaly detected in the fetus, imperforate anus in the newborn, and intractable constipation or neurologic symptoms in the infant and older child. At any age, meningitis can be the presenting symptom and imaging is required for proper investigation. Meningitis, sepsis, urinary tract infections, and, rarely, malignant transformation of a teratoma are serious potential complications. This pictorial review describes the imaging findings, clinical history, surgical interventions, and genetic background in 5 children with this syndrome who presented in our hospital in the interval of 1 year.

Sacral agenesis: a pilot whole exome sequencing and copy number study

Background

Caudal regression syndrome (CRS) or sacral agenesis is a rare congenital disorder characterized by a constellation of congenital caudal anomalies affecting the caudal spine and spinal cord, the hindgut, the urogenital system, and the lower limbs. CRS is a complex condition, attributed to an abnormal development of the caudal mesoderm, likely caused by the effect of interacting genetic and environmental factors. A well-known risk factor is maternal type 1 diabetes.

Method

Whole exome sequencing and copy number variation (CNV) analyses were conducted on 4 Caucasian trios to identify de novo and inherited rare mutations.

Results

In this pilot study, exome sequencing and copy number variation (CNV) analyses implicate a number of candidate genes, including SPTBN5, MORN1, ZNF330, CLTCL1 and PDZD2. De novo mutations were found in SPTBN5, MORN1 and ZNF330 and inherited predicted damaging mutations in PDZD2 (homozygous) and CLTCL1 (compound heterozygous). Importantly, predicted damaging mutations in PTEN (heterozygous), in its direct regulator GLTSCR2 (compound heterozygous) and in VANGL1 (heterozygous) were identified. These genes had previously been linked with the CRS phenotype.

Two CNV deletions, one de novo (chr3q13.13) and one homozygous (chr8p23.2), were detected in one of our CRS patients. These deletions overlapped with CNVs previously reported in patients with similar phenotype.

Conclusion

Despite the genetic diversity and the complexity of the phenotype, this pilot study identified genetic features common across CRS patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0359-2) contains supplementary material, which is available to authorized users.

Comparison in the incidence of anorectal malformations between a first- and third-world referral center

PURPOSE

Aim of study was to evaluate the differences in incidence and presentation of anorectal malformations (ARMs) between selected Pediatric Surgery Divisions in the Republic of South Africa (ZAR) and Italy.

METHODS

A retrospective cohort study involved analysis of clinical records of patients with ARM born between 2005 and 2012. Type of ARM, maternal age, birth weight, gestational age, presence of associated anomalies and delayed diagnosis were analyzed.

RESULTS

335 patients were included in this study. Of note, statistically significant differences between the African and European patient groups were observed in a male predominance in the ZAR patient population. In addition, female recto-perineal fistulas were diagnosed in significantly more Italian patients than in ZAR. Furthermore, a more advanced maternal age and a lower gestational age was noted in the European cohort with a minimal delay in initial diagnosis as opposed to the African counterpart. Both centers reported recto-perineal fistula as the most common malformation in male patients.

CONCLUSION

With the exception of perineal fistulas in females, the incidence of specific subtypes of ARMs was similar in the two groups. This may be of importance when extrapolating European study conclusion to the South African setting.

A new hereditary congenital facial palsy case supports arg5 in HOX-DNA binding domain as possible hot spot for mutations

Moebius syndrome (MBS) is a rare congenital disorder characterized by rhombencephalic mal development, mainly presenting with facial palsy with limited gaze abduction. Most cases are sporadic, possibly caused by a combination of environmental and genetic factors; however, no proven specific associations have been yet established. Hereditary congenital facial palsy (HCFP) is an autosomal dominant congenital dysinnervation syndrome, recognizable by the isolated dysfunction of the seventh cranial nerve. Mutant mice for Hoxb1 were reported to present with facial weakness, resembling MBS. Recently a homozygous mutation altering arg5 residue of HOXB1 homeodomain into cys5 was identified in two families with HCFP. We screened 95 sporadic patients diagnosed as MBS or HCFP for mutations in HOXB1. A novel homozygous alteration was identified in one HCFP case, affecting the same residue, resulting to his5. In silico protein analysis predicted stronger HOXB1-DNA binding properties for his5 than cys5 that resulted to milder phenotype. It should be noted that, inclusive of the previous report, only two mutations revealed in HOXB1 associated with HCFP involved the same amino acid arg5 in HOXB1 residing in HOXB1-DNA-PBX1 ternary complex.

Sequencing of the DKK1 gene in patients with anorectal malformations and hypospadias

Anorectal malformations (ARM) are rare congenital malformations of the gastrointestinal tract. Approximately 60% of the patients have additional congenital malformations, such as hypospadias. A recently published article showed that deletion of one single gene, dickkopf WNT signaling pathway inhibitor-1 (Dkk1), resulted in an imperforate anus with rectourinary fistula and preputial hypospadias in mice. To determine whether DKK1 also plays a role in the etiology of ARM and hypospadias in humans, we sequenced the four exons of the DKK1 gene in 17 patients affected with both ARM and hypospadias. No new potential disease-causing variant was identified. However, we detected a known non-synonymous variant in one patient, which was predicted in silico to be damaging, and the corresponding unaffected amino acid is highly conserved.

CONCLUSION

In this human study, a potential interesting non-synonymous variant was found in the DKK1 gene. Whether this variant plays a contributory role in the genesis of ARM or hypospadias would require a much larger study.

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.

HLXB9 gene expression, and nuclear location during in vitro neuronal differentiation in the SK-N-BE neuroblastoma cell line

Different parts of the genome occupy specific compartments of the cell nucleus based on the gene content and the transcriptional activity. An example of this is the altered nuclear positioning of the HLXB9 gene in leukaemia cells observed in association with its over-expression. This phenomenon was attributed to the presence of a chromosomal translocation with breakpoint proximal to the HLXB9 gene. Before becoming an interesting gene in cancer biology, HLXB9 was studied as a developmental gene. This homeobox gene is also known as MNX1 (motor neuron and pancreas homeobox 1) and it is relevant for both motor neuronal and pancreatic beta cells development. A spectrum of mutations in this gene are causative of sacral agenesis and more broadly, of what is known as the Currarino Syndrome, a constitutional autosomal dominant disorder. Experimental work on animal models has shown that HLXB9 has an essential role in motor neuronal differentiation. Here we present data to show that, upon treatment with retinoic acid, the HLXB9 gene becomes over-expressed during the early stages of neuronal differentiation and that this corresponds to a reposition of the gene in the nucleus. More precisely, we used the SK-N-BE human neuroblastoma cell line as an in vitro model and we demonstrated a transient transcription of HLXB9 at the 4th and 5th days of differentiation that corresponded to the presence, predominantly in the cell nuclei, of the encoded protein HB9. The nuclear positioning of the HLXB9 gene was monitored at different stages: a peripheral location was noted in the proliferating cells whereas a more internal position was noted during differentiation, that is while HLXB9 was transcriptionally active. Our findings suggest that HLXB9 can be considered a marker of early neuronal differentiation, possibly involving chromatin remodeling pathways.

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: report of five consecutive patients

INTRODUCTION

The Currarino syndrome is regarded as a developmental disorder based on its recognized etiological heterogeneity. This syndrome is thought to result from abnormal separation of the neuroectoderm from the endoderm. Our aim was to report the neurosurgical management of Currarino syndrome in children and adults and to describe what clinician could do if the Currarino triad was suspected.

CASE REPORTS

We present five cases of Currarino triad who underwent surgical intervention. All patients had sacral bony deformity, anorectal malformations, and anterior sacral meningocele. A 40-year-old-male had chronic constipation. He was incidentally diagnosed with Currarino syndrome. A 19-year-old-female suffered from a slight weakness in lower extremities and urinary incontinence. Her past medical history was remarkable for anal atresia. The other three cases were children.

CONCLUSION

When an anterior sacral meningocele is encountered, Currarino syndrome should be taken into consideration. Although it is rarity, the Currarino syndrome might be one of the causes of chronic constipation. Endoscopic or endoscope-assisted surgery via a posterior sacral route can be feasible for treatment of some of the patients with anterior sacral meningocele. Anterior meningocele pouch associated with Currarino syndrome will regresses over time following transdural ligation of its neck.

Oncogenic deregulation of NKL homeobox gene MSX1 in mantle cell lymphoma

NKL homeobox gene MSX1 is physiologically expressed during embryonic hematopoiesis. Here, we detected MSX1 overexpression in three examples of mantle cell lymphoma (MCL) and one of acute myeloid leukemia (AML) by screening 96 leukemia/lymphoma cell lines via microarray profiling. Moreover, in silico analysis identified significant overexpression of MSX1 in 3% each of patients with MCL and AML, confirming aberrant activity in subsets of both types of malignancies. Comparative expression profiling analysis and subsequent functional studies demonstrated overexpression of histone acetyltransferase PHF16 together with transcription factors FOXC1 and HLXB9 as activators of MSX1 transcription. Additionally, we identified regulation of cyclin D1/CCND1 by MSX1 and its repressive cofactor histone H1C. Fluorescence in situ hybridization in MCL cells showed that t(11;14)(q13;q32) results in detachment of CCND1 from its corresponding repressive MSX1 binding site. Taken together, we uncovered regulators and targets of homeobox gene MSX1 in leukemia/lymphoma cells, supporting the view of a recurrent genetic network that is reactivated in malignant transformation.

Spinal cord malformations

Malformations of the spinal cord are one of the most frequent malformations. They should be clearly divided into two completely different families of malformations: open dysraphisms and occult dysraphisms. Open dysraphism mostly consists in myelomeningocele (MMC). Its incidence is 1/1000 live births with a wide variation. Folic acid supplementation has been shown to reduce its risk. In most cases, the diagnosis is done prenatally by serum screening and ultrasound and may lead to termination of pregnancy. In case of decision to continue pregnancy, surgical treatment must be achieved during the first days of life, and in 50 to 90% of cases, a ventricular shunt must be installed. The follow-up of these children must be continued throughout life looking for late complications (Chiari II and syringomyelia, vertebral problems, neuropathic bladder, tethered cord). Occult dysraphisms are a heterogeneous group of malformations. Lipomas (filum and conus) are the most frequent and their treatment remains controversial. Diastematomyelia, neurenteric cysts, dermal sinus, and more complex forms (Currarino syndrome) belong to this group. Most of them can and must be diagnosed prenatally or at birth by careful examination of the lower back for the cutaneous stigmata of the disease to decrease the risk of neurological, urological, or orthopedic permanent handicap.

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.

Anorectal atresia and variants at predicted regulatory sites in candidate genes

Anorectal atresia is a serious birth defect of largely unknown etiology but candidate genes have been identified in animal studies and human syndromes. Because alterations in the activity of these genes might lead to anorectal atresia, we selected 71 common variants predicted to be in transcription factor binding sites, CpG windows, splice sites, and miRNA target sites of 25 candidate genes, and tested for their association with anorectal atresia. The study population comprised 150 anorectal atresia cases and 623 control infants without major malformations. Variants predicted to affect transcription factor binding, splicing, and DNA methylation in WNT3A, PCSK5, TCF4, MKKS, GLI2, HOXD12, and BMP4 were associated with anorectal atresia based on a nominal P value < 0.05. The GLI2 and BMP4 variants are reported to be moderately associated with gene expression changes (Spearman's rank correlation coefficients between -0.260 and 0.226). We did not find evidence for interaction between maternal pre-pregnancy obesity and variants in MKKS, a gene previously associated with obesity, on the risk of anorectal atresia. Our results for MKKS support previously suggested associations with anorectal malformations. Our findings suggest that more research is needed to determine whether altered GLI2 and BMP4 expression is important in anorectal atresia in humans.

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.

Clinical utility of chromosomal microarray analysis

OBJECTIVE

To test the hypothesis that chromosomal microarray analysis frequently diagnoses conditions that require specific medical follow-up and that referring physicians respond appropriately to abnormal test results.

METHODS

A total of 46,298 postnatal patients were tested by chromosomal microarray analysis for a variety of indications, most commonly intellectual disability/developmental delay, congenital anomalies, dysmorphic features, and neurobehavioral problems. The frequency of detection of abnormalities associated with actionable clinical features was tallied, and the rate of physician response to a subset of abnormal tests results was monitored.

RESULTS

A total of 2088 diagnoses were made of more than 100 different disorders that have specific clinical features that warrant follow-up. The detection rate for these conditions using high-resolution whole-genome microarrays was 5.4%, which translates to 35% of all clinically significant abnormal test results identified in our laboratory. In a subset of cases monitored for physician response, appropriate clinical action was taken more than 90% of the time as a direct result of the microarray finding.

CONCLUSIONS

The disorders diagnosed by chromosomal microarray analysis frequently have clinical features that need medical attention, and physicians respond to the diagnoses with specific clinical actions, thus arguing that microarray testing provides clinical utility for a significant number of patients tested.

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.

Presacral masses in children: presentation, aetiology and risk of malignancy

AIM

The risk of malignant changes in presacral tumours in children was investigated in relation to age at diagnosis, type of presentation and origin of the tumour.

METHOD

A retrospective review was carried out in 17 patients surgically treated for congenital presacral masses over a 22-year period.

RESULTS

Constipation was the main symptom in 14 (82%) of 17 patients. The lesions were evident on digital examination in 14 patients. Mature teratoma (n = 9, 64%) was the most common lesion, including three malignancies. Currarino syndrome was diagnosed in 10 (71%) patients. Two unclassified variant HLXB9 gene mutations were found in five (29%) patients who underwent genetic testing.

CONCLUSION

Congenital presacral tumours in children were mostly mature teratomas, either as sacrococcygeal teratomas or as part of the Currarino syndrome. The risk of malignancy in patients older than 1 year necessitates early surgical resection.

Mutation analysis of the motor neuron and pancreas homeobox 1 (MNX1, former HLXB9) gene in Swedish patients with Currarino syndrome

BACKGROUND

Currarino syndrome (CS) is a triad consisting of partial sacral agenesis, presacral mass, and anorectal malformations, typically anal stenosis but the phenotype varies. The main cause of this monogenic disorder is mutations in the motor neuron and pancreas homeobox 1 gene. We describe the clinical and genetic findings in 4 unrelated Swedish cases with CS and their relatives.

METHODS

We performed mutation analysis of the motor neuron and pancreas homeobox 1 gene in 4 cases with CS by DNA sequence analysis as well as multiplex ligation-dependent probe amplification. In addition, array comparative genome hybridization was performed in 2 cases. Including relatives, totally, 14 individuals were analyzed.

RESULTS

We found 2 previously described mutations, 1 de novo nonsense mutation (p.Gln212X) and 1 maternally inherited frameshift mutation (p.Pro18ProfsX38). In the family with the frameshift mutation, we also detected the same maternally inherited mutation in 3 of the proband's 4 brothers, who displayed varying symptoms. All mutation carriers had presacral tumors, although 2 were asymptomatic.

CONCLUSION

Our findings emphasize the need for genetic counseling and mutation analysis in patients with CS to detect tumors early. It shows the importance of evaluation of the sacrum and the presacral region in patients with anal stenosis with or without funnel anus. Family members of index cases should be considered for evaluation even if they are asymptomatic.

The homeobox gene HLXB9 is upregulated in a morphological subset of poorly differentiated hepatocellular carcinoma

The prognostic outcome for hepatocellular carcinoma (HCC) remains poor. Disease progression is accompanied by dedifferentiation of the carcinoma, a process that is not well understood. The aim of this study was to get more insight into the molecular characteristics of dedifferentiated carcinomas using high throughput techniques. Microarray-based global gene expression analysis was performed on five poorly differentiated HCC cell lines compared with non-neoplastic hepatic controls and a set of three cholangiolar carcinoma (CC) cell lines. The gene with the highest upregulation was HLXB9. HLXB9 is a gene of the homeobox genfamily important for the development of the pancreas. RT-PCR confirmed the upregulation of HLXB9 in surgical specimens of carcinoma tissue, suggesting its biological significance. Interestingly, HLXB9 upregulation was primary observed in poorly differentiated HCC with a pseudoglandular pattern compared with a solid pattern HCC or in moderate or well-differentiated HCC. Additional the expression of translated HLXB9, the protein HB9 (NCBI: NP_001158727), was analyzed by western blotting. Expression of HB9 was only detected in the cytoplasm but not in the nuclei of the HCC cells. For validation CC were also investigated. Again, we found an upregulation of HLXB9 in CC cells accompanied by an expression of HB9 in the cytoplasms of these tumor cells, respectively. In conclusion, homeobox HLXB9 is upregulated in poorly differentiated HCC with a pseudoglandular pattern. The translated HB9 protein is found in the cytoplasm of these HCC and CC. We therefore assume HLXB9 as a possible link in the understanding of the development of HCC and CC, respectively.

The dual role of HLXB9 in leukemia

BACKGROUND

The HLXB9 gene encodes a homeodomain containing transcription factor which has been implicated in the development of both solid and hematological malignancies. In leukemia it is one of the two fused genes, along with ETV6, in a recurrent translocation frequently observed in infant AML.

PROCEDURE

Here we investigate the role of epigenetic inactivation of the HLXB9 gene in leukemia. Quantitative DNA methylation analysis was performed using the COBRA assay, and qRT-PCR was used to assess the effects of methylation on expression in hematological cell lines and primary ALL samples.

RESULTS

Hypermethylation of the HLXB9 gene was found to be a frequent event in childhood ALL, occurring in 33% of cases. However, it was rarely or never observed in other types of leukemia, including AML, CML, and CLL, with the exception of adult ALL, in which 39% of cases were hypermethylated. Furthermore, hypermethylation of HLXB9 results in loss of expression in hematological cell lines and primary ALL samples.

CONCLUSION

These results suggest that HLXB9 may have a dual role in childhood leukemia, as an oncogene in infant AML but as a tumor suppressor in childhood ALL.