RESUMEN
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.
Asunto(s)
Proteínas Hedgehog , Holoprosencefalia , Hipertelorismo , Fenotipo , Humanos , Proteínas Hedgehog/genética , Femenino , Holoprosencefalia/genética , Holoprosencefalia/patología , Adolescente , Hipertelorismo/genética , Hipertelorismo/patología , Adulto , Mutación/genéticaRESUMEN
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.
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Holoprosencefalia , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos , Humanos , Femenino , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/genética , Embarazo , Holoprosencefalia/genética , Holoprosencefalia/diagnóstico , Adulto , Diagnóstico Prenatal/métodos , Secuenciación del Exoma , Ultrasonografía Prenatal , Prosencéfalo/anomalías , Prosencéfalo/embriología , HeterocigotoRESUMEN
OBJECTIVES: The main objective of this study was to evaluate how an apparently minor anomaly of the sphenoid bone, observed in a haploinsufficient mouse model for Sonic Hedgehog (Shh), affects the growth of the adult craniofacial region. This study aims to provide valuable information to orthodontists when making decisions regarding individuals carrying SHH mutation. MATERIALS AND METHODS: The skulls of embryonic, juvenile and adult mice of two genotypes (Shh heterozygous and wild type) were examined and measured using landmark-based linear dimensions. Additionally, we analysed the clinical characteristics of a group of patients and their relatives with SHH gene mutations. RESULTS: In the viable Shh+/ - mouse model, bred on a C57BL/6J background, we noted the presence of a persistent foramen at the midline of the basisphenoid bone. This particular anomaly was attributed to the existence of an ectopic pituitary gland. We discovered that this anomaly led to premature closure of the intrasphenoidal synchondrosis and contributed to craniofacial deformities in adult mice, including a longitudinally shortened skull base. This developmental anomaly is reminiscent of that commonly observed in human holoprosencephaly, a disorder resulting from a deficiency in SHH activity. However, sphenoid morphogenesis is not currently monitored in individuals carrying SHH mutations. CONCLUSION: Haploinsufficiency of Shh leads to isolated craniofacial skeletal hypoplasia in adult mouse. This finding highlights the importance of radiographic monitoring of the skull base in all individuals with SHH gene mutations.
Asunto(s)
Proteínas Hedgehog , Holoprosencefalia , Adulto , Animales , Humanos , Ratones , Proteínas Hedgehog/genética , Holoprosencefalia/genética , Ratones Endogámicos C57BL , Mutación , Hueso EsfenoidesRESUMEN
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.
Asunto(s)
Alelos , Holoprosencefalia , Fenotipo , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Anodoncia , Labio Leporino/genética , Labio Leporino/patología , Fisura del Paladar/genética , Fisura del Paladar/patología , Anomalías Craneofaciales/genética , Anomalías Craneofaciales/patología , Heterocigoto , Holoprosencefalia/genética , Holoprosencefalia/patología , Homocigoto , Incisivo/anomalías , Proteínas de la Membrana/genética , Mutación Missense/genéticaAsunto(s)
Dedos/anomalías , Holoprosencefalia , Polidactilia , Dedos del Pie/anomalías , Embarazo , Femenino , Humanos , Holoprosencefalia/diagnóstico por imagen , Holoprosencefalia/genética , Primer Trimestre del Embarazo , Síndrome de la Trisomía 13/diagnóstico , Polidactilia/diagnóstico , Polidactilia/genética , Trisomía/diagnóstico , Trisomía/genética , Ultrasonografía PrenatalRESUMEN
Mutations in SHH and several other genes encoding components of the Hedgehog signaling pathway have been associated with holoprosencephaly syndromes, with craniofacial anomalies ranging in severity from cyclopia to facial cleft to midfacial and mandibular hypoplasia. Studies in animal models have revealed that SHH signaling plays crucial roles at multiple stages of craniofacial morphogenesis, from cranial neural crest cell survival to growth and patterning of the facial primordia to organogenesis of the palate, mandible, tongue, tooth, and taste bud formation and homeostasis. This article provides a summary of the major findings in studies of the roles of SHH signaling in craniofacial development, with emphasis on recent advances in the understanding of the molecular and cellular mechanisms regulating the SHH signaling pathway activity and those involving SHH signaling in the formation and patterning of craniofacial structures.
Asunto(s)
Proteínas Hedgehog , Holoprosencefalia , Animales , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Cresta Neural/metabolismo , Holoprosencefalia/genética , Holoprosencefalia/metabolismo , Morfogénesis/genética , Transducción de Señal/genéticaRESUMEN
BACKGROUND: Diprosopus is a rare malformation of still unclear aetiology. It describes a laterally double faced monocephalic and single-trunk individual and has to be distinguished from the variant Janus type diprosopus. RESULTS: We examined seven double-faced foetuses, five showing true diprosopus, and one each presenting as monocephalic Janiceps and parasitic conjoined twins. Four of the foetuses presented with (cranio)rachischisis, and two had secondary hydrocephaly. Three foetuses showed cerebral duplication with concordant holoprosencephaly, Dandy-Walker cyst and/or intracranial anterior encephalocele. In the Janiceps twins, cerebral duplication was accompanied by cerebral di-symmetry. In the parasitic twins the cyclopic facial aspects were suggestive of concordant holoprosencephaly. In one of the true diprosopus cases, pregnancy was achieved after intracytoplasmic sperm injection. Whole-exome sequencing, perfomed in one case, did not reveal any possible causative variants.The comparison of our double-faced foetuses to corresponding artistic representations from the Tlatilco culture allowed retrospective assignment of hairstyles to brain malformations. CONCLUSION: Brain malformations in patients with diprosopus may not be regarded as an independent event but rather as a sequel closely related to the duplication of the notochord and neural plate and as a consequence of the cerebral and associated craniospinal structural instabilities.
Asunto(s)
Holoprosencefalia , Gemelos Siameses , Embarazo , Femenino , Humanos , Masculino , Holoprosencefalia/genética , Museos , Estudios Retrospectivos , Semen , EncéfaloRESUMEN
During embryonic development, the forebrain roof plate undergoes invagination, leading to separation of the cerebral hemispheres. Any defects in this process, in humans, lead to middle interhemispheric holoprosencephaly (MIH-HPE). In this study, we have identified a previously unreported downstream mediator of retinoic acid (RA) signaling, CNKSR2, which is expressed in the forebrain roof plate in the chick embryo. Knockdown of CNKSR2 affects invagination, cell proliferation and patterning of the roof plate, similar to the phenotypes observed upon inhibition of RA signaling. We further demonstrate that CNKSR2 functions by modulating the Ras/Raf/MEK signaling. This appears to be crucial for patterning of the forebrain roof plate and its subsequent invagination, leading to the formation of the cerebral hemispheres. Thus, a set of novel molecular players have been identified that regulate the morphogenesis of the avian forebrain.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Holoprosencefalia , Prosencéfalo , Tretinoina , Animales , Embrión de Pollo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Holoprosencefalia/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Prosencéfalo/embriología , Tretinoina/metabolismoRESUMEN
Hedgehog acyltransferase gene (HHAT)-associated Nivelon-Nivelon-Mabile syndrome (NNMS) is a rare genetic disorder of multiple system involvement with microcephaly, central nervous system malformations, skeletal dysplasia, and 46,XY sex reversal. Other variable and inconsistent features reported in this disorder are muscle spasms, facial dysmorphism, prenatal onset growth restriction, microphthalmia, and holoprosencephaly. This is the sixth postnatal reported patient with biallelic variants in HHAT gene, who presented with microcephaly, short stature, muscle hypertrophy, muscle spasms, and facial dysmorphism. The most prominent and presenting finding in this patient were muscle hypertrophy and muscle spasms which had a clinical response to phenytoin and acetazolamide treatment. Our report emphasizes the phenotypic variability of NNMS and further reiterates muscle spasms as an important clinical manifestation of this extremely rare condition.
Asunto(s)
Enanismo , Holoprosencefalia , Microcefalia , Humanos , Microcefalia/genética , Proteínas Hedgehog , Holoprosencefalia/genética , Síndrome , EspasmoRESUMEN
Holoprosencephaly (HPE) is a clinically and genetically heterogeneous disease, which can be associated with various prenatal comorbidities not always detectable on prenatal ultrasound. We report on the case of a foetus carrying a semi-lobar HPE diagnosed at ultrasound, for which a fetal autopsy and a whole exome sequencing were performed following a medical termination of pregnancy. Neuropathological examination confirmed the semi-lobar HPE and general autopsy disclosed a total pancreas agenesis. Whole exome sequencing found the CNOT1 missense c.1603C>T, p.(Arg535Cys), occurring de novo in the foetus. The same variant was previously reported in 5 unrelated children. All individuals had HPE, and 4 out of 5 presented endo- and exocrine pancreatic insufficiency or total pancreas agenesis. CNOT1 encodes a subunit of the CCRN4-NOT complex, expressed at the early stage of embryonic development. This report is the first fetal description of the phenotype associating HPE and pancreatic agenesis linked to the recurrent CNOT1 missense c.1603C>T, p.(Arg535Cys). This finding strengthens the hypothesis of a specific recurrent variant associated with a particular phenotype of HPE and pancreas agenesis. The fetal autopsy that revealed the pancreas agenesis was crucial in guiding the genetic diagnosis and enabling accurate genetic counselling.
Asunto(s)
Holoprosencefalia , Femenino , Feto/patología , Holoprosencefalia/diagnóstico , Holoprosencefalia/genética , Holoprosencefalia/patología , Humanos , Fenotipo , Embarazo , Síndrome , Factores de Transcripción/genéticaRESUMEN
Hartsfield syndrome is a rare condition characterised by the co-occurrence of ectrodactyly and holoprosencephaly spectrum disorders; cleft lip and palate is a common associated feature. This is due to either monoallelic, or less commonly, biallelic variants in FGFR1 with a loss of function or dominant negative effect. To date 37 individuals have been reported, including two instances of germline mosaicism. We report a further family with Hartsfield syndrome due to a novel variant in FGFR1, with two affected fetuses, and somatic and germline mosaicism in the father detected on Sanger sequencing. The father had not come to medical attention prior to this finding. In light of our findings and those in the published literature, we suggest that mosaicism, either germline or germline and somatic, may be a relatively frequent finding, affecting 3 of 35 (9%) reported families, which has important implications for genetic counselling.
Asunto(s)
Labio Leporino , Fisura del Paladar , Holoprosencefalia , Labio Leporino/genética , Fisura del Paladar/genética , Dedos/anomalías , Deformidades Congénitas de la Mano , Holoprosencefalia/genética , Humanos , Discapacidad Intelectual , MosaicismoRESUMEN
Adult form and function are dependent upon the activity of specialized signaling centers that act early in development at the embryonic midline. These centers instruct the surrounding cells to adopt a positional fate and to form the patterned structures of the phylotypic embryo. Abnormalities in these processes have devastating consequences for the individual, as exemplified by holoprosencephaly in which anterior midline development fails, leading to structural defects of the brain and/or face. In the 25 years since the first association between human holoprosencephaly and the sonic hedgehog gene, a combination of human and animal genetic studies have enhanced our understanding of the genetic and embryonic causation of this congenital defect. Comparative biology has extended the holoprosencephaly network via the inclusion of gene mutations from multiple signaling pathways known to be required for anterior midline formation. It has also clarified aspects of holoprosencephaly causation, showing that it arises when a deleterious variant is present within a permissive genome, and that environmental factors, as well as embryonic stochasticity, influence the phenotypic outcome of the variant. More than two decades of research can now be distilled into a framework of embryonic and genetic causation. This framework means we are poised to move beyond our current understanding of variants in signaling pathway molecules. The challenges now at the forefront of holoprosencephaly research include deciphering how the mutation of genes involved in basic cell processes can also cause holoprosencephaly, determining the important constituents of the holoprosencephaly permissive genome, and identifying environmental compounds that promote holoprosencephaly. This article is categorized under: Congenital Diseases > Stem Cells and Development Congenital Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Molecular and Cellular Physiology Congenital Diseases > Environmental Factors.
Asunto(s)
Holoprosencefalia , Animales , Biología , Encéfalo , Proteínas Hedgehog/genética , Holoprosencefalia/genética , Humanos , Mamíferos/metabolismo , Ratones , Transducción de Señal/genéticaRESUMEN
Holoprosencephaly is a central nervous system malformation, characterized by incomplete or total lack of division of prosencephalon hemispheres, which is commonly accompanied by craniofacial malformations. A 9-month-gestation aborted American Quarter Horse fetus was submitted for postmortem examination. The fetus lacked haircoat and had severe facial malformations including marked shortening/absence of the maxillary, incisive and nasal bones, bilateral anophthalmia, and pre-maxillary agenesis. The prosencephalon was small and nearly spherical, represented by a single lobe, with no visible separation between cerebral hemispheres. The olfactory bulbs, piriform lobes, and the optic chiasm were absent. At cross sectioning of the prosencephalon, the inner structures of the brain were completely absent, and replaced by a monoventricle lined by the remaining compressed cortex, and the thalami were fused. Since mutations in the sonic hedgehog (SHH) gene have been associated with human holoprosencephaly, the three coding SHH exons were sequenced using liver DNA of the aborted foal. The obtained SHH sequence was similar to the Equus caballus SHH mRNA sequence deposited in Genbank (XM_023640069.1); therefore, no polymorphism in the coding region of this gene justifying the phenotype was observed. This is the first report of alobar holoprosencephaly in horses.
Asunto(s)
Holoprosencefalia , Enfermedades de los Caballos , Feto Abortado , Animales , Feto , Proteínas Hedgehog/genética , Holoprosencefalia/genética , Holoprosencefalia/veterinaria , Caballos , ProsencéfaloRESUMEN
OBJECTIVE: We present the application of quantitative fluorescent polymerase chain reaction (QF-PCR) for the rapid confirmation of trisomy 13 of maternal origin in a pregnancy with fetal holoprosencephaly (HPE), cyclopia, polydactyly, omphalocele and cell culture failure. CASE REPORT: A 21-year-old, gravida 2, para 0, woman was referred for termination of the pregnancy at 17 weeks of gestation because of the abnormal ultrasound finding of alobar HPE. The pregnancy was subsequently terminated, and a 118-g malformed male fetus was delivered with cyclopia, bilateral postaxial polydactyly of the hands and ruptured omphalocele. Postmortem cell culture of the placental tissue and umbilical cord was not successful. The parental karyotypes were normal. QF-PCR analysis using the polymorphic DNA markers of D13S1810, D13S790 and D13S251 on the DNA extracted from placenta, umbilical cord and parental bloods showed trisomy 13 of maternal origin. CONCLUSION: Perinatal diagnosis of concomitant HPE, polydactyly and omphalocele should raise a suspicion of fetal trisomy 13. QF-PCR analysis is useful for rapid confirmation of trisomy 13 and the parental origin especially under the circumstance of cell culture failure, and the information acquired is very useful for genetic counseling of the parents.
Asunto(s)
Hernia Umbilical , Holoprosencefalia , Polidactilia , Reacción en Cadena de la Polimerasa/métodos , Síndrome de la Trisomía 13/diagnóstico , Ultrasonografía Prenatal , Adulto , Amniocentesis , Técnicas de Cultivo de Célula , Femenino , Feto , Hernia Umbilical/diagnóstico por imagen , Hernia Umbilical/genética , Holoprosencefalia/diagnóstico por imagen , Holoprosencefalia/genética , Humanos , Masculino , Placenta , Polidactilia/diagnóstico , Polidactilia/genética , Embarazo , Trisomía/diagnóstico , Trisomía/genética , Síndrome de la Trisomía 13/genética , Adulto JovenRESUMEN
BACKGROUND: Holoprosencephaly is a spectrum of developmental disorder of the embryonic forebrain in which there is failed or incomplete separation of the prosencephalon into two cerebral hemispheres. To date, dominant mutations in sonic hedgehog (SHH) pathway genes are the predominant Mendelian causes, and have marked interfamilial and intrafamilial phenotypical variabilities. METHODS: We describe two families in which offspring had holoprosencephaly spectrum and homozygous predicted-deleterious variants in phospholipase C eta-1 (PLCH1). Immunocytochemistry was used to examine the expression pattern of PLCH1 in human embryos. We used SHH as a marker of developmental stage and of early embryonic anatomy. RESULTS: In the first family, two siblings had congenital hydrocephalus, significant developmental delay and a monoventricle or fused thalami with a homozygous PLCH1 c.2065C>T, p.(Arg689*) variant. In the second family, two siblings had alobar holoprosencephaly and cyclopia with a homozygous PLCH1 c.4235delA, p.(Cys1079ValfsTer16) variant. All parents were healthy carriers, with no holoprosencephaly spectrum features. We found that the subcellular localisation of PLCH1 is cytoplasmic, but the p.(Cys1079ValfsTer16) variant was predominantly nuclear. Human embryo immunohistochemistry showed PLCH1 to be expressed in the notorcord, developing spinal cord (in a ventral to dorsal gradient), dorsal root ganglia, cerebellum and dermatomyosome, all tissues producing or responding to SHH. Furthermore, the embryonic subcellular localisation of PLCH1 was exclusively cytoplasmic, supporting protein mislocalisation contributing to the pathogenicity of the p.(Cys1079ValfsTer16) variant. CONCLUSION: Our data support the contention that PLCH1 has a role in prenatal mammalian neurodevelopment, and deleterious variants cause a clinically variable holoprosencephaly spectrum phenotype.
Asunto(s)
Holoprosencefalia , Fosfolipasas de Tipo C , Animales , Proteínas Hedgehog/genética , Holoprosencefalia/genética , Holoprosencefalia/metabolismo , Humanos , Mamíferos/metabolismo , Mutación , Fenotipo , Fosfolipasas de Tipo C/genéticaRESUMEN
Variants in transcription factor GLI2 have been associated with hypopituitarism and structural brain abnormalities, occasionally including holoprosencephaly (HPE). Substantial phenotypic variability and nonpenetrance have been described, posing difficulties in the counseling of affected families. We present three individuals with novel likely pathogenic GLI2 variants, two with truncating and one with a de novo missense variant p.(Ser548Leu), and review the literature for comprehensive phenotypic descriptions of individuals with confirmed pathogenic (a) intragenic GLI2 variants and (b) chromosome 2q14.2 deletions encompassing only GLI2. We show that most of the 31 missense variants previously reported as pathogenic are likely benign or, at most, low-risk variants. Four Zn-finger variants: p.(Arg479Gly), p.(Arg516Pro), p.(Gly518Lys), and p.(Tyr575His) were classified as likely pathogenic, and three other variants as possibly pathogenic: p.(Pro253Ser), p.(Ala593Val), and p.(Pro1243Leu). We analyze the phenotypic descriptions of 60 individuals with pathogenic GLI2 variants and evidence a morbidity spectrum that includes hypopituitarism (58%), HPE (6%) or other brain structure abnormalities (15%), orofacial clefting (17%) and dysmorphic facial features (35%). We establish that truncating and Zn-finger variants in GLI2 are associated with a high risk of hypopituitarism, and that a solitary median maxillary central incisor is part of the GLI2-related phenotypic variability. The most prevalent phenotypic feature is post-axial polydactyly (65%) which is also the mildest phenotypic expression of the condition, reported in many parents of individuals with systemic findings. Our approach clarifies clinical risks and the important messages to discuss in counseling for a pathogenic GLI2 variant.
Asunto(s)
Holoprosencefalia , Hipopituitarismo , Holoprosencefalia/genética , Humanos , Hipopituitarismo/genética , Hipopituitarismo/metabolismo , Factores de Transcripción de Tipo Kruppel/genética , Mutación , Proteínas Nucleares/genética , Fenotipo , Zinc , Proteína Gli2 con Dedos de Zinc/genéticaRESUMEN
OBJECTIVE: Middle interhemispheric (MIH) variant of holoprosencephaly (HPE) or syntelencephaly is a rare prosencephalic cleavage disorder. In literature, few cases of accurate prenatal diagnosis have been reported. We report on four additional prenatally diagnosed cases. METHODS: Between 2012 and 2017, four cases of MIH HPE were retrieved. Data on prenatal imaging, genetic analysis, and pathological investigation are collected. A "PubMed" and "Trip database" search were conducted revealing six papers reporting on 11 prenatally diagnosed cases. RESULTS AND DISCUSSION: Four additional cases of MIH HPE were diagnosed at an earlier gestational age (between 17 and 25 weeks of gestation) compared with 11 cases from the literature review (15-39 weeks). First trimester transvaginal ultrasound facilitates correct differentiation between the severe HPE variants. Frequent association with ZIC2 mutation was found in nearly 50% of the cases (5/11) compared with one case in our series. CONCLUSIONS: MIH variant of HPE is detectable from the early second trimester and should be considered in the differential diagnosis when the cavum septi pellucidi (CSP) is absent. Genetic analysis and autopsy should be conducted to investigate this more recent and rare variant.
Asunto(s)
Holoprosencefalia , Embarazo , Femenino , Humanos , Lactante , Holoprosencefalia/diagnóstico por imagen , Holoprosencefalia/genética , Diagnóstico Prenatal/métodos , Segundo Trimestre del Embarazo , Primer Trimestre del Embarazo , Pruebas Genéticas , Ultrasonografía PrenatalRESUMEN
OBJECTIVE: We present rapid diagnosis of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction (QF-PCR) in a pregnancy with multiple fetal abnormalities. CASE REPORT: A 35-year-old, primigravid woman was referred for amniocentesis at 24 weeks of gestation because of multiple congenital anomalies in the fetus. Prenatal ultrasound at 23 weeks of gestation revealed holoprosencephaly, premaxillary agenesis, postaxial polydactyly of the left hand and overriding aorta. Amniocentesis was performed subsequently, and QF-PCR analysis using the polymorphic DNA markers of D13S789 (13q22.3), D13S790 (13q31.1) and D13S767 (13q31.3) on the DNA extracted from uncultured amniocytes and parental bloods showed trisomy 13 of maternal origin. Conventional cytogenetic analysis on the cultured amniocytes confirmed trisomy 13. The pregnancy was subsequently terminated, and a malformed fetus was delivered with multiple anomalies consistent with the prenatal diagnosis. CONCLUSION: QF-PCR analysis is useful for rapid confirmation of trisomy 13 and the parental origin when prenatal ultrasound findings are suspicious of fetal trisomy 13.
Asunto(s)
Anomalías Múltiples/genética , Amniocentesis/métodos , Cardiopatías Congénitas , Holoprosencefalia/genética , Polidactilia/genética , Síndrome de la Trisomía 13/diagnóstico , Síndrome de la Trisomía 13/genética , Anomalías Múltiples/diagnóstico por imagen , Adulto , Hibridación Genómica Comparativa , Femenino , Feto , Dedos/anomalías , Holoprosencefalia/diagnóstico por imagen , Humanos , Hibridación Fluorescente in Situ , Polidactilia/diagnóstico por imagen , Reacción en Cadena de la Polimerasa , Embarazo , Fluorescencia Cuantitativa Inducida por la Luz , Dedos del Pie/anomalíasRESUMEN
Pathogenic gene variants in humans that affect the sonic hedgehog (SHH) pathway lead to severe brain malformations with variable penetrance due to unknown modifier genes. To identify such modifiers, we established novel congenic mouse models. LRP2-deficient C57BL/6N mice suffer from heart outflow tract defects and holoprosencephaly caused by impaired SHH activity. These defects are fully rescued on a FVB/N background, indicating a strong influence of modifier genes. Applying comparative transcriptomics, we identified Pttg1 and Ulk4 as candidate modifiers upregulated in the rescue strain. Functional analyses showed that ULK4 and PTTG1, both microtubule-associated proteins, are positive regulators of SHH signaling, rendering the pathway more resilient to disturbances. In addition, we characterized ULK4 and PTTG1 as previously unidentified components of primary cilia in the neuroepithelium. The identification of genes that powerfully modulate the penetrance of genetic disturbances affecting the brain and heart is likely relevant to understanding the variability in human congenital disorders.