ARID1A-BAF coordinates ZIC2 genomic occupancy for epithelial-to-mesenchymal transition in cranial neural crest specification.

The BAF chromatin remodeler regulates lineage commitment including cranial neural crest cell (CNCC) specification. Variants in BAF subunits cause Coffin-Siris syndrome (CSS), a congenital disorder characterized by coarse craniofacial features and intellectual disability. Approximately 50% of individuals with CSS harbor variants in one of the mutually exclusive BAF subunits, ARID1A/ARID1B. While Arid1a deletion in mouse neural crest causes severe craniofacial phenotypes, little is known about the role of ARID1A in CNCC specification. Using CSS-patient-derived ARID1A+/- induced pluripotent stem cells to model CNCC specification, we discovered that ARID1A-haploinsufficiency impairs epithelial-to-mesenchymal transition (EMT), a process necessary for CNCC delamination and migration from the neural tube. Furthermore, wild-type ARID1A-BAF regulates enhancers associated with EMT genes. ARID1A-BAF binding at these enhancers is impaired in heterozygotes while binding at promoters is unaffected. At the sequence level, these EMT enhancers contain binding motifs for ZIC2, and ZIC2 binding at these sites is ARID1A-dependent. When excluded from EMT enhancers, ZIC2 relocates to neuronal enhancers, triggering aberrant neuronal gene activation. In mice, deletion of Zic2 impairs NCC delamination, while ZIC2 overexpression in chick embryos at post-migratory neural crest stages elicits ectopic delamination from the neural tube. These findings reveal an essential ARID1A-ZIC2 axis essential for EMT and CNCC delamination.

Holoprosencephaly spectrum: an up-to-date overview of classification, genetics and neuroimaging.

Holoprosencephaly (HPE) is a complex forebrain congenital malformation with widely variable outcomes. It represents a disorder of ventral induction, which begins in the fifth gestational week. Its main feature is forebrain cleavage failure, which prevents the brain complete division into right and left hemispheres, the normal development of midline structures, and the deep brain structure. Based on the severity of prosencephalic cleavage failure, three classic forms (lobar, semilobar, and alobar) were described, and subsequently, interhemispheric variant (syntelencephaly) and septopreoptic variants were proposed. This review proposes a practical imaging approach to diagnosing HPE spectrum disorders, allowing an easier recognition and earlier diagnosis, which is essential for prenatal care and adequate parental counseling. In addition, we intend to simplify the understanding of HPE through a didactic discussion, schematic illustrations, and descriptions of each entity's current classification and critical neuroimaging features, as well as the main differential diagnosis of HPE.

CNOT1 p.Arg535Cys variant in holoprosencephaly with late onset diabetes mellitus.

Holoprosencephaly (HPE) results from a lack of cleavage of the prosencephalon. It has a complex etiology, resulting from chromosome abnormalities or single gene variants in the Sonic hedgehog signaling pathway. A single variant, p.Arg535Cys in CNOT1, has been described in HPE in association with pancreatic agenesis and neonatal diabetes. Here, we report on a case of HPE and p.Arg535Cys in CNOT1 without pancreatic agenesis where the patient presented with diabetes mellitus in adolescence. This case reinforces the role of CNOT1 in pancreatic development. We suggest that individuals with p.Arg535Cys in CNOT1 with no pancreas abnormalities observed at birth should be screened for diabetes during follow-up.

Dual white matter pathology in fetal holoprosencephaly featuring concurrent malformative and destructive features: A case series.

Holoprosencephaly (HPE) is a classic brain malformation involving defective forebrain induction and patterning. Cases of HPE bearing white matter abnormalities have not been well documented, with only rare cases exhibiting hypoxic-ischemic damage. However, neuroradiologic studies of HPE using diffusion tensor imaging have suggested the presence of white matter architectural disarray. Described in this case series are the clinicopathologic features of 8 fetuses with HPE who underwent autopsy at BC Children's Hospital. All 8 cases exhibited subacute to chronic, periventricular leukomalacia (PVL)-like white matter pathology, with 7 of 8 cases also demonstrating aberrant white matter tracts, one of which manifested as a discreet bundle crossing the midline within the ventral aspects of the fused deep gray nuclei. In 6 of these 7 cases, the PVL-like pathology resided within this aberrant white matter tract. Original workup, alongside an additional HPE-focused next-generation sequencing panel identified a likely etiologic cause for the HPE in 4 cases, with an additional 2 cases exhibiting a variant of unknown significance in genes previously suggested to be involved in HPE. Despite our in-depth clinicopathologic and molecular review, no unifying etiology was definitively identified among our series of fetal HPE bearing this unusual pattern of white matter pathology.

CDON Mutation Related to Nose Deformity with Variable Expression in Holoprosencephaly in an Iranian Family: A Case Report.

Holoprosencephaly, a complicated brain abnormality arising from incomplete prosencephalon cleavage, affects both the forebrain and the face. Holoprosencephaly Type 11, with variable expression or partial penetrance, is caused by CDON pathogenic variants associated with the disrupted Sonic Hedgehog (SHH)-pathway. Herein, we aimed to describe a family with genetic nose problems. After counselling and drawing pedigree in Farhud's Genetic Clinic, Tehran, Iran in 2021, DNA extraction of a proband and a few members of his family (patient and control) was conducted. Whole exome sequencing was utilized for detecting the gene and its variant in the proband with a nose deformity. The results were confirmed with Sanger sequencing. This variant was checked in other members by Sanger sequencing. Analysis of the Exome data showed a heterozygous splicing variant in the CDON gene (NM_016952; c.3276+1G>T) in the proband who had a nose deformity and then the results were confirmed with Sanger sequencing. Such a variant was observed in Proband's brother with a nose deformity and was not observed in Proband's cousin with no abnormal phenotype. Recent investigations, in an Iranian family, with a heterozygous splicing CDON mutation as a human candidate gene are discussed for the first time in relation to the likely pathogenesis of facial deformities, particularly nose deformity, in Holoprosencephaly.

Knockout mice with pituitary malformations help identify human cases of hypopituitarism.

BACKGROUND: Congenital hypopituitarism (CH) and its associated syndromes, septo-optic dysplasia (SOD) and holoprosencephaly (HPE), are midline defects that cause significant morbidity for affected people. Variants in 67 genes are associated with CH, but a vast majority of CH cases lack a genetic diagnosis. Whole exome and whole genome sequencing of CH patients identifies sequence variants in genes known to cause CH, and in new candidate genes, but many of these are variants of uncertain significance (VUS). METHODS: The International Mouse Phenotyping Consortium (IMPC) is an effort to establish gene function by knocking-out all genes in the mouse genome and generating corresponding phenotype data. We used mouse embryonic imaging data generated by the Deciphering Mechanisms of Developmental Disorders (DMDD) project to screen 209 embryonic lethal and sub-viable knockout mouse lines for pituitary malformations. RESULTS: Of the 209 knockout mouse lines, we identified 51 that have embryonic pituitary malformations. These genes not only represent new candidates for CH, but also reveal new molecular pathways not previously associated with pituitary organogenesis. We used this list of candidate genes to mine whole exome sequencing data of a cohort of patients with CH, and we identified variants in two unrelated cases for two genes, MORC2 and SETD5, with CH and other syndromic features. CONCLUSIONS: The screening and analysis of IMPC phenotyping data provide proof-of-principle that recessive lethal mouse mutants generated by the knockout mouse project are an excellent source of candidate genes for congenital hypopituitarism in children.

Use of an Orthodontic and Otolaryngological Approach in an Infant with Holoprosencephaly.

Holoprosencephaly is a complex human brain malformation resulting from incomplete cleavage of the prosencephalon into both hemispheres. Congenital nasal pyriform aperture stenosis (CNPAS) is sometimes found in patients with mild forms of holoprosencephaly. Surgical treatment is required. Low-invasive surgical approaches involve balloon dilation of the pyriform opening. We present the case of an 8-day-old girl diagnosed with holoprosencephaly, CNPAS, and the presence of a solitary median maxillary central incisor. Once examined by neonatologist, geneticist, pneumologist, otolaryngologist, and pediatric dentist, a combined otolaryngological-orthodontic approach was used. The obstruction of the right nasal cavity was treated by widening the nasal cavities and stabilizing them with a balloon dilation technique. After surgery, the respiratory space was increased by applying a neonatal palatal expander plate (NPEP) considering the palatal deformity: ogival shaped, anterior vertex growth direction, reduction of transverse diameters. The NPEP promoted distraction of the median palatine suture and assisted the nasal dilation. Therefore, after the insertion of NPEP, the physiological sucking-swallowing mechanism was activated. In infants with CNPAS, NPEP can be useful to ensure the safe stability of nasal dilation. A multidisciplinary approach is fundamental. In our experience, the close collaboration between an otolaryngologist and orthodontist is essential for the management of the patient with CNPAS.

Prenatal identification of a pathogenic maternal FGFR1 variant in two consecutive pregnancies with fetal forebrain malformations.

OBJECTIVE: Holoprosencephaly (HPE) is the most common aberration of forebrain development, and it leads to a wide spectrum of developmental and craniofacial anomalies. HPE etiology is highly heterogeneous and includes both chromosomal abnormalities and single-gene defects. METHODS: Here, we report an FGFR1 heterozygous variant detected by prenatal exome sequencing and inherited from the asymptomatic mother, in association with recurrent neurological abnormalities in the HPE spectrum in two consecutive pregnancies. RESULTS: Individuals with germline pathogenic variants in FGFR1 (MIM: 136350) show extensive phenotypic variability, which ranges from asymptomatic carriers to hypogonadotropic hypogonadism, arhinencephaly, Kallmann's syndrome with associated features such as cleft lip and palate, skeletal anomalies, isolated HPE, and Hartsfield syndrome. CONCLUSION: The presented case supports the role of exome sequencing in prenatal diagnosis when fetal midline structural anomalies are suggestive of a genetic etiology, as early as the first trimester of gestation. The profound heterogeneity of FGFR1 allelic disorders needs to be considered when planning prenatal screening even in asymptomatic carriers.

Truncating variants of the sterol recognition region of SHH cause hypertelorism phenotype rather than hypotelorism-holoprosencephaly.

Sonic hedgehog signaling molecule (SHH) is a key molecule in the cilia-mediated signaling pathway and a critical morphogen in embryogenesis. The association between loss-of-function variants of SHH and holoprosencephaly is well established. In mice experiments, reduced or increased signaling of SHH have been shown to be associated with narrowing or excessive expansion of the facial midline, respectively. Herein, we report two unrelated patients with de novo truncating variants of SHH presenting with hypertelorism rather than hypotelorism. The first patient was a 13-year-old girl. Her facial features included hypertelorism, strabismus, telecanthus, malocclusion, frontal bossing, and wide widow's peak. She had borderline developmental delay and agenesis of the corpus callosum. She had a nonsense variant of SHH: Chr7(GRCh38):g.155802987C > T, NM_000193.4:c.1302G > A, p.(Trp434*). The second patient was a 25-year-old girl. Her facial features included hypertelorism and wide widow's peak. She had developmental delay and agenesis of the corpus callosum. She had a frameshift variant of SHH: Chr7(GRCh38):g.155803072_155803074delCGGinsT, NM_000193.4:c.1215_1217delCCGinsA, p.(Asp405Glufs*92). The hypertelorism phenotype contrasts sharply with the prototypical hypotelorism-holoprosencephaly phenotype associated with loss-of-function of SHH. We concluded that a subset of truncating variants of SHH could be associated with hypertelorism rather than hypotelorism.

Post-mortem rapid aneuploidy testing for holoprosencephaly.

BACKGROUND: Abortion and fetal death are common in fetuses with holoprosencephaly, so genetic examinations often have to be made in a post-mortem setting. The efficiency of the conventional karyotyping using cultured fibroblasts in these situations is limited due to frequent culture failure. In the current study, archived cases of holoprosencephaly, where post-mortem genetic evaluation was requested and sufficient frozen material was available, were reevaluated using the quantitative fluorescence polymerase chain reaction (QF-PCR) technique. METHODS: Testing for aneuploidies of chromosomes 13, 15, 16, 18, 21, 22, X, and Y with the QF-PCR technique was carried out on DNA isolated from archived frozen chorionic villi in seven cases of holoprosencephaly. RESULTS: QF-PCR was successful in all seven cases. Two cases of trisomy 13, two cases of triploidy, and one case of trisomy 18 was found meaning a 71% diagnostic yield. The success rate of QF-PCR (100%, 7/7) was superior compared to conventional karyotyping (43%, 3/7). CONCLUSIONS: Rapid aneuploidy testing using the QF-PCR technique is a simple, reliable, time- and cost-effective method sufficient to conclude the etiologic investigation in the majority of holoprosencephaly cases post-mortem.

A male fetus with cyclopia was discovered after miscarriage: A rare case report from Syria.

Key Clinical Message: This case of alobar holoprosencephaly and cyclopia emphasizes the value of prenatal check-ups, particularly in low-income countries. Early ultrasound diagnosis leads to early gestational termination, preventing psychological trauma for the parents. Abstract: Alobar holoprosencephaly is a rare-occurrence malformation with a bad prognosis linked to cyclopia, the most severe cranial feature. Prenatal examinations are essential for identifying these deformities and preventing parental mental health damage.

Cheiloplasty for False Median Cleft Lip Associated With Holoprosencephaly: The Use of Skin Graft for Philtrum Reconstruction, the Risk of Simultaneous Columella Reconstruction.

A false median cleft lip is a congenital malformation associated with holoprosencephaly. Cheiloplasty is an effective treatment for false median cleft lip. In the past, holoprosencephaly had a poor prognosis with extremely low survival rates; consequently, cheiloplasty was rarely performed. However, with the recent improvement in survival and prognosis with advances in medical care, patients survive and can now undergo cheiloplasty. We report a case of cheiloplasty performed using a skin graft for philtrum reconstruction. The lip contour was satisfactory because the insufficient tissue was resolved by filling the skin graft, which could not be resolved by midline suture closure. We did not perform columella reconstruction considering the safety; however, oxygenation temporarily destabilized owing to postoperative airway stenosis. Careful postoperative management is necessary even if the columella is not reconstructed.

DISP1 deficiency: Monoallelic and biallelic variants cause a spectrum of midline craniofacial malformations.

PURPOSE: DISP1 encodes a transmembrane protein that regulates the secretion of the morphogen, Sonic hedgehog, a deficiency of which is a major cause of holoprosencephaly (HPE). This disorder covers a spectrum of brain and midline craniofacial malformations. The objective of the present study was to better delineate the clinical phenotypes associated with division transporter dispatched-1 (DISP1) variants. METHODS: This study was based on the identification of at least 1 pathogenic variant of the DISP1 gene in individuals for whom detailed clinical data were available. RESULTS: A total of 23 DISP1 variants were identified in heterozygous, compound heterozygous or homozygous states in 25 individuals with midline craniofacial defects. Most cases were minor forms of HPE, with craniofacial features such as orofacial cleft, solitary median maxillary central incisor, and congenital nasal pyriform aperture stenosis. These individuals had either monoallelic loss-of-function variants or biallelic missense variants in DISP1. In individuals with severe HPE, the DISP1 variants were commonly found associated with a variant in another HPE-linked gene (ie, oligogenic inheritance). CONCLUSION: The genetic findings we have acquired demonstrate a significant involvement of DISP1 variants in the phenotypic spectrum of midline defects. This underlines its importance as a crucial element in the efficient secretion of Sonic hedgehog. We also demonstrated that the very rare solitary median maxillary central incisor and congenital nasal pyriform aperture stenosis combination is part of the DISP1-related phenotype. The present study highlights the clinical risks to be flagged up during genetic counseling after the discovery of a pathogenic DISP1 variant.

Genotype-phenotype analysis of ocular findings in Rubinstein-Taybi syndrome - A case report and review of literature.

BACKGROUND: Rubinstein-Taybi syndrome (RSTS) is a rare genetic syndrome with a wide range of phenotypic presentations, including characteristic facial features. A variety of ocular abnormalities have been described in patients with RSTS. The genetic etiology of RSTS is heterogeneous but often involves two major genes, CREBBP (cAMP-response element binding protein-binding protein) and EP300 (E1A binding protein p300), with CREBBP variants responsible for the majority of the cases. MATERIALS AND METHODS: We report a new case of female patient with a novel variant in CREBBP (c.4495C>G), with clinical features consistent with RSTS. We performed a literature review to search for possible genotype-phenotype relationships between the type of variant in CREBBP and frequency of ocular presentations. A PubMed search generated 12 articles that met our inclusion criteria. With the addition of our patient, there were a total of 163 patients included for mutation analysis (164 variants given one patient had two different variants). RESULTS: Our review revealed that the most common variant types were frameshift (25%), gross deletion (23%), nonsense (18%), and intragenic deletions (13%). There does not appear to be an obvious hot spot location. A total of 127 patients were included for genotype-phenotype analysis of ocular features (36 patients were excluded as unable to discern variant type). The most frequent ocular features in patients with RSTS were down-slanting palpebral fissure (74%), arched eyebrows (56%), long eyelashes (52%), and strabismus (23%). CONCLUSIONS: Our results suggest that currently there is no clear genotype-phenotype relationship between the type of variant and frequency of associated ocular features in RSTS patients.

Holoprosencefalia alobar. reporte de caso / Holoprosencephaly alobar. Case Report

Desde el advenimiento de la ecografía obstétrica y estudios invasivos además genéticos fetales han ayudado en la detección antenatal de anormalidades congénitas siendo uno de los objetivos básicos de la vigilancia fetal anteparto. La combinación de ambas técnicas ofrece, hoy en día un abordaje completo en términos de diagnóstico prenatal. Se cree que muchos trastornos del desarrollo surgen de factores de riesgos genéticos y ambientales. Uno de estos es la holoprosencefalia, sirve como modelo para comprender diversas formas de etiología multifactorial. El análisis genómico, la epidemiología y estudios mecánicos de modelos animales han revelado que factores de riesgo interactúan para producir resultados de desarrollo adversos. La holoprosencefalia es consecuencia de factores genéticos y/o ambientales que interrumpen la especificación de la línea media del prosencéfalo en formación. Estas alteraciones dan lugar a una amplia gama de consecuencias fenotípicas para el cerebro y la cara del nuevo ser humano en formación. Son comunes en 1 de 250 fetos humanos, pero el 97% no sobrevive al nacimiento. La patogenia molecular precisa de la holoprosencefalia sigue siendo desconocida. Aquí, describimos nuestra comprensión de los principales factores impulsores que conducen a patologías de holoproscencefalia y elaboramos nuestro enfoque de genómica integrada multifactorial. Las tecnologías genómicas proporcionan una visión sin precedentes de la variación asociada a la enfermedad. A continuación, se describe un caso de diagnóstico prenatal de trisomía 13 y holoprosencefalia. En éste, se logró establecer un diagnóstico antenatal anatómico y genético preciso.

Since the advent of obstetric ultrasound and invasive studies, fetal genetics have helped in the antenatal detection of congenital abnormalities, being one of the basic objectives of antepartum fetal surveillance. The combination of both techniques currently offers a complete approach in terms of prenatal diagnosis. Many developmental disorders are thought to arise from genetic and environmental risk factors. One of these is holoprosencephaly, which serves as a model for understanding various forms of multifactorial etiology. Genomic analysis, epidemiology, and mechanistic studies of animal models have revealed that risk factors interact to produce adverse developmental outcomes. Holoprosencephaly results from genetic and/or environmental factors that disrupt the specification of the midline of the forming forebrain. These alterations result in a wide range of phenotypic consequences for the brain and face of the newly developing human being. They are common in 1 in 250 human fetuses, but 97% do not survive birth. The precise molecular pathogenesis of holoprosencephaly remains unknown. Here, we describe our understanding of the main drivers leading to holoproscencephaly pathologies and elaborate on our multifactorial integrated genomics approach. Genomic technologies provide unprecedented insight into disease-associated variation. A case of prenatal diagnosis of trisomy 13 and holoprosencephaly is described below. In this study, it was possible to establish an accurate anatomical and genetic antenatal diagnosis.

Differential alternative splicing analysis links variation in ZRSR2 to a novel type of oral-facial-digital syndrome.

PURPOSE: Oral-facial-digital (OFD) syndromes are genetically heterogeneous developmental disorders, caused by pathogenic variants in genes involved in primary cilia formation and function. We identified a previously undescribed type of OFD with brain anomalies, ranging from alobar holoprosencephaly to pituitary anomalies, in 6 unrelated families. METHODS: Exome sequencing of affected probands was supplemented with alternative splicing analysis in patient and control lymphoblastoid and fibroblast cell lines, and primary cilia structure analysis in patient fibroblasts. RESULTS: In 1 family with 2 affected males, we identified a germline variant in the last exon of ZRSR2, NM_005089.4:c.1211_1212del NP_005080.1:p.(Gly404GlufsTer23), whereas 7 affected males from 5 unrelated families were hemizygous for the ZRSR2 variant NM_005089.4:c.1207_1208del NP_005080.1:p.(Arg403GlyfsTer24), either occurring de novo or inherited in an X-linked recessive pattern. ZRSR2, located on chromosome Xp22.2, encodes a splicing factor of the minor spliceosome complex, which recognizes minor introns, representing 0.35% of human introns. Patient samples showed significant enrichment of minor intron retention. Among differentially spliced targets are ciliopathy-related genes, such as TMEM107 and CIBAR1. Primary fibroblasts containing the NM_005089.4:c.1207_1208del ZRSR2 variant had abnormally elongated cilia, confirming an association between defective U12-type intron splicing, OFD and abnormal primary cilia formation. CONCLUSION: We introduce a novel type of OFD associated with elongated cilia and differential splicing of minor intron-containing genes due to germline variation in ZRSR2.

Efficacy of tolvaptan in an infant with syndrome of inappropriate antidiuretic hormone secretion associated with holoprosencephaly: A case report.

BACKGROUND: Holoprosencephaly (HPE) is a congenital malformation with various degrees of incomplete separation of the cerebral hemispheres due to differentiation disorders of the forebrain. Although HPE with diabetes insipidus due to associated pituitary dysfunction has been reported, HPE with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is very rare. Tolvaptan, a vasopressin V2 receptor antagonist, is effective in adults with SIADH. However, there is no report of its efficacy in infants with SIADH. The purpose of this report is to demonstrate that tolvaptan is effective for SIADH in infants and that administration of tolvaptan eliminates the need for restriction of water intake and sodium administration. CASE SUMMARY: A 2414-g female infant was born at 38 wk by normal vaginal delivery. Facial anomalies and head magnetic resonance imaging indicated semilobar HPE. After birth, she had hyponatremia due to SIADH and was treated using water and sodium restriction. However, she developed an exaggerated response to the fluid restrictions, resulting in large fluctuations in serum sodium levels. Subsequent administration of tolvaptan improved the fluctuations in serum sodium levels without the need for adjustment of water or sodium administration. Serum sodium was maintained within the normal range after discontinuation of tolvaptan at 80 d of life. There were no side effects, such as hypernatremia or liver dysfunction, during the administration of tolvaptan. CONCLUSION: This is the first report on the safety and efficacy of tolvaptan in an infant with SIADH associated with HPE.

Holoprosencephaly (HPE) : case report and review of the literature.

INTRODUCTION: Holoprosencephaly (HPE) is a complex brain malformation resulting from a medial cleavage defect of the prosencephalon into right and left hemispheres, occurring during early embryonic development. CASE PRESENTATION: We report an alobar holoprosencephaly diagnosed on imaging (obstetrical ultrasound) and revealed by a polymalformative syndrome in an 8-month-old infant. DISCUSSION: Holoprosencephaly affects the forebrain and face, causing neurological manifestations and facial anomalies of varying severity. HPE is a cerebral midline anomaly. CONCLUSION: Its fetal prognosis is extremely guarded, particularly for the alobar form.

The utility of balloon dilation for piriform aperture stenosis - A first line surgical treatment.

AIM: Describe the long-term outcomes of patients with piriform aperture stenosis managed with balloon dilation. METHODS: Review of current literature. A retrospective case series of 6 patients with piriform aperture stenosis initially managed with balloon dilation at a tertiary paediatric hospital. RESULTS: Six neonates diagnosed with piriform aperture were managed with balloon dilation under general anaesthesia after failing conservative treatment. Average age at first dilation was 28 days old (range 6-54). The piriform aperture was an average width of 5.15 mm, with a 4-6.5 mm range, as measured on axial CT scan. The average width at 25% of the nasal cavity, 50% and 75% was 7.7 mm, 9.3 mm and 9.98 mm respectively. Four neonates required only a single balloon dilation - two of these were stented post-operatively. The remaining two neonates required multiple balloon dilations with eventual drill-out through a sublabial approach. There was a trend of smaller piriform and nasal cavity diameters in those who required multiple procedures. The mean follow-up was 30 months. CONCLUSION: Balloon dilation should be considered for primary operative management in neonates with piriform aperture stenosis who fail medical interventions. Balloon dilation can treat the narrowing at and beyond the piriform aperture. Patients who require more than one dilation are more likely to have a smaller piriform aperture and may need a drill-out procedure. The impact of nasal stents on outcomes is unclear.

Adult Radiographic Presentation of Corpus Callosal Agenesis With a Single Interhemispheric Cyst and Dandy-Walker Malformation: A Case Report.

Agenesis or dysgenesis of the corpus callosum may occur due to ischemic, toxic, traumatic, or another insult to the fetus in the first trimester. Occasionally, such a malformation is associated with an interhemispheric cyst, among other central nervous system anomalies. Holoprosencephaly tends to mimic this radiographic presentation, which is where key imaging findings are helpful to differentiate between these entities. We present a 56-year-old male patient who was found to have a monoventricle, corpus callosum agenesis, interhemispheric cyst, and a Dandy-Walker malformation. The patient presented with a right acetabular fracture with computed tomography (CT) of the brain revealing the congenital brain abnormalities. The patient's past medical history was notable for a seizure disorder identified during early adulthood. The CT scan of the head revealed a large monoventricle with an associated midline dorsal interhemispheric cyst and a Dandy-Walker malformation. The absence of both the corpus callosum and septum pellucidum was noted, with the presence of a monoventricle, leading to an initial differential of holoprosencephaly. Further review of the findings suggested instead a rare congenital presentation consisting of corpus callosum agenesis and an interhemispheric cyst. This case highlights a unique radiographic presentation of multiple brain anomalies, rarely presented in non-pediatric literature, which may help determine appropriate surgical and medical management for similarly affected adult individuals.