Compound heterozygous splicing CDON variants result in isolated ocular coloboma.

Ocular coloboma is caused by failure of optic fissure closure during development and recognized as part of the microphthalmia, anophthalmia, and coloboma (MAC) spectrum. While many genes are known to cause colobomatous microphthalmia, relatively few have been reported in coloboma with normal eye size. Genetic analysis including trio exome sequencing and Sanger sequencing was undertaken in a family with two siblings affected with bilateral coloboma of the iris, retina, and choroid. Pathogenic variants in MAC genes were excluded. Trio analysis identified compound heterozygous donor splice site variants in CDON, a cell-surface receptor known to function in the Sonic Hedgehog pathway, c.928 + 1G > A and c.2650 + 1G > T, in both affected individuals. Heterozygous missense and truncating CDON variants are associated with dominant holoprosencephaly (HPE) with incomplete penetrance and Cdon-/- mice display variable HPE and coloboma. A homozygous nonsense allele of uncertain significance was recently identified in a consanguineous patient with coloboma and a second molecular diagnosis. We report the first compound heterozygous variants in CDON as a cause of isolated coloboma. CDON is the first HPE gene identified to cause recessive coloboma. Given the phenotypic overlap, further examination of HPE genes in coloboma is indicated.

Nasal fistula, epidermal cyst and hypernatremia in a girl presenting holoprosencephaly due to a rare ZIC2 point mutation.

Holoprosencephaly is the most common brain malformation in humans and it is a complex genetic disorder. We report on a patient with holoprosencephaly caused by a rare ZIC2 mutation presenting a bifid nose associated with a nasal fistula and an epidermal cyst, besides hypernatremia. The patient was a 1 year and 4 months old girl that developed an important neuropsychomotor delay. Currently, she uses a wheelchair to move around and only emits sounds. Computed tomography (CT) scan revealed a semilobar holoprosencephaly and a Dandy-Walker variant. Head magnetic resonance imaging also disclosed corpus callosum agenesis and prefrontal subarachnoid space enlargement. On physical examination at 1 year and 4 months of age, we verified growth retardation, microcephaly, bilateral epicantic fold, upslanting palpebral fissures, bifid nose, and limbs spasticity secondary to hypertonia. Later, she began to present hypernatremia; however, its precise cause was not identified. At 6 years and 10 months of age, a nasal fistula was suspected. Facial CT scan showed an epidermal cyst at cartilaginous portion of the nasal septum. High resolution GTG-Banding karyotype was normal. However, molecular analysis through direct sequencing technique showed a mutation at regulatory region of the ZIC2 gene: c.1599*954T > A, a genetic variation previously described only in a Brazilian patient. Our patient presented findings still not reported in literature among patients with holoprosencephaly, including those with ZIC2 mutations. Thus, the spectrum of abnormalities associated to ZIC2 mutations may be broader and include other defects as those observed in our patient.

Holoprosencephaly in Kabuki syndrome.

Kabuki syndrome is a rare, multi-systemic disorder of chromatin regulation due to mutations in either KMT2D or KDM6A that encode a H3K4 methyltransferase and an H3K27 demethylase, respectively. The associated clinical phenotype is a direct result of temporal and spatial changes in gene expression in various tissues including the brain. Although mild to moderate intellectual disability is frequently recognized in individuals with Kabuki syndrome, the identification of brain anomalies, mostly involving the hippocampus and related structures remains an exception. Recently, the first two cases with alobar holoprosencephaly and mutations in KMT2D have been reported in the medical literature. We identified a de novo, pathogenic KMT2D variant (c.6295C > T; p.R2099X) using trio whole-exome sequencing in a 2-year-old female with lobar holoprosencephaly, microcephaly and cranio-facial features of Kabuki syndrome. This report expands the spectrum of brain anomalies associated with Kabuki syndrome underscoring the important role of histone modification for early brain development.

Novel synonymous and missense variants in FGFR1 causing Hartsfield syndrome.

Hartsfield syndrome is a rare clinical entity characterized by holoprosencephaly and ectrodactyly with the variable feature of cleft lip/palate. In addition to these symptoms patients with Hartsfield syndrome can show developmental delay of variable severity, isolated hypogonadotropic hypogonadism, central diabetes insipidus, vertebral anomalies, eye anomalies, and cardiac malformations. Pathogenic variants in FGFR1 have been described to cause phenotypically different FGFR1-related disorders such as Hartsfield syndrome, hypogonadotropic hypogonadism with or without anosmia, Jackson-Weiss syndrome, osteoglophonic dysplasia, Pfeiffer syndrome, and trigonocephaly Type 1. Here, we report three patients with Hartsfield syndrome from two unrelated families. Exome sequencing revealed two siblings harboring a novel de novo heterozygous synonymous variant c.1029G>A, p.Ala343Ala causing a cryptic splice donor site in exon 8 of FGFR1 likely due to gonadal mosaicism in one parent. The third case was a sporadic patient with a novel de novo heterozygous missense variant c.1868A>G, p.(Asp623Gly).

Novel heterozygous variants in KMT2D associated with holoprosencephaly.

Lysine methyltransferase 2D (KMT2D; OMIM 602113) encodes a histone methyltransferase involved in transcriptional regulation of the beta-globin and estrogen receptor as part of a large protein complex known as activating signal cointegrator-2-containing complex (ASCOM). Heterozygous germline mutations in the KMT2D gene are known to cause Kabuki syndrome (OMIM 147920), a developmental multisystem disorder. Neither holoprosencephaly nor other defects in human forebrain development have been previously associated with Kabuki syndrome. Here we report two patients diagnosed with alobar holoprosencephaly in their antenatal period with de novo monoallelic KMT2D variants identified by trio-based exome sequencing. The first patient was found to have a stop-gain variant c.12565G>T (p.Gly4189*), while the second patient had a missense variant c.5A>G (p.Asp2Gly). Phenotyping of each patient did not reveal any age-related feature of Kabuki syndrome. These two cases represent the first report on association between KMT2D and holoprosencephaly.

Holoprosencephaly, orofacial cleft, and frontonaso-orbital encephaloceles: Genetic evaluation of a possible new syndrome.

Here we report on a Brazilian child who presented semilobar holoprosencephaly, frontonasal encephaloceles and bilateral cleft lip and palate. Malformations also included agenesis of the corpus callosum, abnormal cortical gyres, dilation of the aqueduct, bilateral endolymphatic sac, bilateral cystic cocci-vestibular malformation, and a cribriform defect. The 3D TC craniofacial images showed abnormal frontonasal transition region, with a bone bifurcation, and partial agenesis of nasal bone. The trunk and upper and lower limbs were normal. To our knowledge, this rare association of holoprocensephaly with frontonaso-orbital encephaloceles without limb anomalies has never been reported before. Karyotype was normal. SNP-array showed no copy-number alterations but revealed 25% of regions of homozygosity (ROH) with normal copy number, indicating a high coefficient of inbreeding, which significantly increases the risk for an autosomal recessive disorder. Whole exome sequencing analysis did not reveal any pathogenic or likely pathogenic variants. We discuss the possible influence of two variants of uncertain significance found within the patient's ROHs. First, a missense p.(Gly394Ser) in PCSK9, a gene involved in the regulation of plasma low-density lipoprotein cholesterol. Second, an inframe duplication p.(Ala75_Ala81dup) in SP8, a zinc-finger transcription factor that regulates signaling centers during craniofacial development. Further studies and/or the identification of other patients with a similar phenotype will help elucidate the genetic etiology of this complex case.

Prenatal diagnosis of holoprosencephaly associated with Smith-Lemli-Opitz syndrome (SLOS) in a 46,XX fetus.

OBJECTIVE: To show the importance of measuring cholesterol precursor levels in amniotic fluid in all pregnancies with ultrasound features (such as holoprosencephaly) suggestive of Smith-Lemli-Opitz syndrome (SLOS), after exclusion of chromosomal anomalies. CASE REPORT: A 28-year-old woman, gravida 1 para 0, performed chorionic villus sampling for fetal karyotyping at 13 weeks of gestation due to positive combined first trimester screening in a fetus with increased nuchal translucency and suspected holoprosencephaly. The result was normal - 46,XX. The diagnosis of alobar holoprosencephaly was confirmed at 15 weeks of gestation, and cardiac and limb defects were also identified. Thus, a syndromic cause was considered, specifically a chromosomal microdeletion syndrome or a monogenic entity such as SLOS. The latter was confirmed by measuring 7-dehydrocholesterol (7DHC) and 8-dehydrocholesterol (8DHC) in amniotic fluid. Molecular analysis of DHCR7 gene identified a homozygous mutation in intron 8, c.964-1G>C, providing molecular confirmation for this diagnosis. CONCLUSION: The differential diagnosis of holoprosencephaly is broad. Identification of the cause of holoprosencephaly aids in establishing the prognosis and is essential to ascertain the mode of inheritance for adequate genetic counseling.

Holoprosencephaly: antenatal and postnatal diagnosis and outcome.

OBJECTIVES: The objectives of this study are to ascertain the clinical outcome and overall survival of holoprosencephaly (HPE) patients diagnosed antenatally and postnatally, to determine the accuracy of antenatal diagnosis and to determine the role of neurosurgical intervention in HPE. DESIGN: This is a retrospective review over a 10-year period. PATIENTS: Sixty-three patients were included in the study, 45 were diagnosed by antenatal radiological imaging and 18 were diagnosed by postnatal radiological imaging. Patient data was drawn from Temple Street Children's University Hospital (the national paediatric neurosurgery centre), the National Maternity Hospital in Holle's Street, Dublin, and Our Lady of Sick Children Hospital, Dublin. METHODS: The study was carried out through a review of antenatal and postnatal radiological imaging and reports, clinical charts, GP letters from patient follow-up and telephone conversations with parents of HPE patients. RESULTS: Four patients in the antenatal diagnosis group had follow-up foetal MRI confirming HPE. Twelve in this group had radiological follow-up postnatally, and in five of these, HPE was confirmed. The remaining seven were identified as false positive. Alobar HPE constituted 55 % (21/38) of patients with 95 % mortality. Fifty-one percent had a normal karyotype. The overall survival in the antenatal diagnosis group was 13 %. In the postnatal group, 18 patients were identified, 67 % (12/18) lobar and 33 % (6/18) semilobar. Normal karyotype was found in 72 % (13/18), with an overall survival rate of 56 % (10/18). Neurosurgical intervention in both groups mainly consisted of CSF diversion in the form of ventriculoperitoneal (VP) or cystoperitoneal shunt (CP) (13/67). CONCLUSION: Foetal MRI should be routinely performed in suspected cases of HPE, and reliance on ultrasound alone in the antenatal period may not be sufficient. In our study, there is a high early mortality noted in severe cases of HPE, while milder forms of HPE in children tend to survive beyond infancy albeit with associated complications that required neurosurgical intervention and medical management for other associated systemic anomalies.

Microform holoprosencephaly with bilateral congenital elbow dislocation; increasing the phenotypic spectrum of Steinfeld syndrome.

Steinfeld syndrome (MIM #184705) was first reported in 1982. It is characterised by holoprosencephaly and limb defects, however other anomalies may also be present. Following the initial description, three further cases have been reported in the literature. We report on a 23-year-old girl, with features of microform holoprosencephaly and bilateral congenital elbow dislocation in association with hypoplastic radial heads. She was identified to have a variant in the CDON gene inherited from her father who had ocular hypotelorism, but no other clinical features. We discuss the clinical features of Steinfeld syndrome, and broaden the phenotypic spectrum of this condition. Structural analysis suggests that this variant could lead to destabilisation of binding of CDON with hedgehog proteins. Further work needs to be done to confirm whether mutations in the CDON gene are the cause of Steinfeld syndrome.

Polidactilia, holoprosencefalia, labio y paladar hendido: no siempre es lo que parece / Polydactyly, holoprosencephaly, cleft lip and cleft palate are not always what they seem: Case report

Reportamos un neonato masculino con defectos de línea media, cardiopatía congénita y polidactilia, características sugestivas de trisomía 13. Sin embargo, el reporte de cariotipo fue normal. Por hallazgos clínicos, el diagnóstico final probable fue pseudotrisomía 13. Aunque el pronóstico de ambas condiciones es pobre, los estudios genéticos siempre son necesarios para establecer una adecuada asesoría genética. Si bien hay síndromes con presentación similar, como el de Meckel, el de Smith-Lemli- Opitz, el de Pallister-Hall y el hidroletalus, se puede realizar una aproximación diagnóstica basada en los antecedentes perinatales, el peso al nacer, el tiempo de supervivencia y algunos rasgos característicos de cada síndrome. Además, pueden existir, en algunos países, limitaciones para realizar estudios genéticos, por lo que los criterios clínicos pueden ser relevantes.

We report a male infant with midline defects, congenital heart disease and polydactyly, features suggestive of trisomy 13. However, the report of the karyotype was normal. By clinical findings the final diagnosis was likely to be Pseudotrisomy 13. Although the prognosis is poor in both conditions, the genetic study is always necessary to establish an adequate genetic counseling. Although there are syndromes with similar presentation as Meckel syndrome, Smith-Lemli-Opitz syndrome, Pallister-Hall syndrome and hydrolethalus, it is possible to make a diagnostic approach based on the perinatal history, birth weight, survival time, and some characteristics of each syndrome. However, limitations may exist to perform genetic studies in some countries, therefore the clinical criteria may be relevant.

Holoprosencephaly: a survey of the entity, with embryology and fetal imaging.

Structural malformations of the brain are an important cause of childhood mortality and morbidity, with the latter having long-term financial and psychosocial implications for the affected child and family. Holoprosencephaly (HPE) is a severe brain malformation characterized by abnormal cleavage of the prosencephalon in the 5th gestational week. Aprosencephaly and atelencephaly occur earlier because of failure in the formation of the prosencephalon and telencephalon, respectively. The HPE holoprosencephaly spectrum classically includes alobar, semilobar, and lobar forms, although there are no clear-cut defining features. The middle interhemispheric variant (MIH), also known as syntelencephaly, is classified as a variant of HPE holoprosencephaly with midline interhemispheric fusion. Other conditions sometimes included in the spectrum of HPE holoprosencephaly include septo-optic dysplasia (SOD); "minimal" HPE holoprosencephaly , which is associated with subtle craniofacial malformations and mild developmental delay; and microform HPE holoprosencephaly , which by definition excludes brain involvement. The focus of this article will be on the spectrum of findings visible in fetal manifestation of the HPE holoprosencephaly spectrum. Brain embryology; the imaging characteristics, epidemiology, and embryology of HPE; and the more common associated anomalies, particularly those of the face ("the face predicts the brain") are reviewed. Recognition of these anomalies is important for accurate parental counseling, since the prognosis is poor but not invariably lethal; children with the milder forms may live well into their teens with severe developmental delays, endocrine dysfunction, and disrupted homeostasis. Available data on outcome in surviving children are summarized. Illustrative fetal ultrasonographic and magnetic resonance images are presented with clinical, autopsy, and postnatal imaging correlation.

[Solitary median maxillary central incisor syndrome]. / Het solitaire mediane maxillaire centrale incisief-syndroom.

Solitary Median Maxillary Central Incisor syndrome is a rare condition (prevalence 1:50,000), with the characteristic dental feature of a solitary central incisor in the maxilla, positioned exactly in the midline. This single incisor is symmetrical and can be present in the deciduous as well as in the permanent dentition. The syndrome can occur as a mild form of the broad holoprosencephaly-spectrum, but can also be associated with other characteristics. The etiology is still largely unknown, but the syndrome is probably based especially on genetic causes. Early recognition of the syndrome is of great importance for establishing the diagnosis, for additional investigation, for possible treatment of associated anomalies and for the correct advice concerning the risk of inheritance of severe congenital birth defects, related to holoprosencephaly. Dentists and orthodontists can play an important role in this regard and should therefore be able to recognise the clinical features of this condition and know how to refer a patient for further diagnostic counselling.

Retinal dysplasia of holoprosencephaly.

Retinal dysplasia occurs in the setting of sporadic and syndromic holoprosencephaly, which often has associated ocular malformations. The pathology of this dysplasia, which includes rosettes, has been previously described. However, its funduscopic findings have not been well documented. The authors present the fundus images of a patient with severe holoprosencephaly with retinal dysplasia and bilateral optic nerve colobomas that resulted in death 2 weeks after birth.

A case of Robin sequence, microgastria, radiohumeral synostosis, femoral deficiency, and other unusual findings: a newly recognized syndrome?

In this report, we describe an 8-year-old male with Robin sequence, bilateral radiohumeral synostosis, microgastria, cryptorchidism, dislocated hips, proximal femoral deficiency, and an autism spectrum disorder. This combination of findings has not been previously reported. Features of particular interest are the radiohumeral synostosis and microgastria, both of which are rare defects, and to our knowledge, have not been reported to occur together. We propose that the patient has a newly recognized syndrome consisting of the aforementioned features, the etiology of which is unknown.

[Prenatal diagnosis of central nervous system malformations]. / A központi idegrendszer fejlodési rendellenességeinek praenatalis diagnosztikája.

The prenatal diagnosis of fetal malformations have been the subject of numerous publications in the literature. This has dramatically increased in the last 15 years, mainly due to the advent of high-resolution ultrasound. In addition adequate guidelines issued by professional organizations have encouraged the universal approach to the imaging of fetal anatomy as well as malformations. One of the most significant groups of the fetal anomalies is the central nervous system malformation. Due to its prevalence and severity the praenatal diagnostics of central nervous system malformations got basic significance. In this review we attempted to summarize the recent informations concerning the prenatal diagnostics of the central nervous system anomalies.

Importance of fetal MRI in evaluation of craniofacial deformities.

AIM: This retrospective study aims at demonstrating the importance of a correct and detailed early diagnosis of craniomaxillofacial malformations affecting the fetus, which would (1) allow improvement in ultrasonography (US) diagnosis, (2) help in planning the therapeutic-surgical procedure, and (3) improve handling of the pathology by the families. MATERIALS AND METHODS: Between 2008 and 2011, a sample of 28 fetuses was selected, all with an ultrasound diagnosis of cleft lip (cheiloschisis-CL) and cleft lip and palate (palatoschisis-CLP) and craniofacial malformation, whose mothers had all underwent ultrasound diagnostic examinations and nuclear magnetic resonance (MRI). All cases were submitted to US examination between the 12th and 19th week of pregnancy, US-3D examination performed by a specialist radiologist between the 19th and 22nd week, and MRI examination between the 23rd and 33rd week of pregnancy. RESULTS: The MRI confirmed the ultrasound diagnosis of 16/28 cases and added information in 11/28 cases, and in 1 (1/28) case, the MRI denied previous CL-CLP ultrasound diagnosis. Moreover, in this study MRI improved the analysis of the entire morphology of the fetuses in cases when syndromic involvement with the involvement of other organs needs to be determined. CONCLUSIONS: The MRI method in fetal patients allows to obtain more details regarding the CL-CLP studied, allowing the medical-surgical team to plan, before the birth, the type of postnatal assessment and surgery to be performed, thus minimizing the impact on neonatal health and improving quality of life of both the patient and his family.

Is fetal cerebral MRI worthwhile in antenatally diagnosed isolated cleft lip with or without palate?

OBJECTIVE: This study aims to evaluate the use of fetal brain magnetic resonance imaging (MRI) following an antenatal sonographic diagnosis of isolated cleft lip with or without cleft palate (CL/P). METHOD: This was a retrospective study of 92 fetuses antenatally diagnosed with isolated CL/P on screening ultrasound. All patients underwent expert diagnostic antenatal ultrasound, fetal brain MRI, and karyotype analysis. RESULTS: Five cases were excluded from the study as associated abnormalities were detected on expert ultrasound: corpus callosum agenesis (n = 1), retrognathism (n = 3), and ectrodactyly (n = 1). Fetal MRI diagnosed unsuspected midline cerebral abnormalities in four out of the 87 remaining cases (4.6%): vermis agenesis (n = 1), isolated arhinencephaly (n = 2), and suspicion of pituitary abnormality (n = 1). All karyotype analyses were normal. CONCLUSION: In CL/P, the incidence of associated cerebral abnormalities overlooked on ultrasound is 4.6%. Careful evaluation of midline structures by expert ultrasound in CL/P is necessary and may be sufficient. MRI can be useful if the US examination is limited or in case of family history. However, the choice to proceed to fetal MRI may vary from institution to institution.

Role of foetal MRI in the evaluation of ischaemic-haemorrhagic lesions of the foetal brain.

OBJECTIVE: The purpose of this study is to define the role of foetal magnetic resonance imaging (MRI) in evaluating cerebral ischaemic-haemorrhagic lesions and the extension of parenchymal injuries. STUDY DESIGN: From September 2006 to September 2010, 271 foetal MRI have been performed on cases referred to us for ultrasound suspect of brain abnormalities or cytomegalovirus infection and Toxoplasma serum conversion. Foetal MRI was performed with a 1.5-T magnet system without mother sedation. RESULTS: Foetal MRI detected ischaemic-haemorrhagic lesions in 14 of 271 foetuses, consisting of 5% incidence. MRI confirmed the diagnosis in three of 14 cases with ultrasonography (US) suspect of ischaemic-haemorrhagic lesions associated with ventriculomegaly. In one of 14 cases with US findings of cerebellar haemorrhage, MRI confirmed the diagnosis and provided additional information regarding the parenchymal ischaemic injury. In eight of 14 cases with US suspect of ventriculomegaly (3), corpus callosum agenesis (2), hypoplasia of cerebellar vermis (1), holoprosencephaly (1) and spina bifida (1), MRI detected ischaemic and haemorrhagic lesions unidentified at US examination. In two of 14 foetuses with US suspect of intracerebral space-occupying lesion, MRI modified the diagnosis to extra-axial haematoma associated with dural sinus malformation. Results were compared with post-mortem findings or afterbirth imaging follow-up. CONCLUSIONS: Foetal MRI is an additional imaging modality in the diagnosis of cerebral ischemic-haemorrhagic lesions, and it is useful in providing further information on the extension of the parenchymal injury and associated abnormalities, thus improving delivery management.