Total colonic aganglionosis and cleft palate in a newborn with Janus-cysteine 618 mutation of RET proto-oncogene: a case report

Abstract Background Hirschsprung disease, the most important congenital colonic dysmotility in children results from neural crest migration, differentiation, proliferation, or apoptosis defects where the rearranged during transfection (RET)-Protooncogene pathway has a central role. Although palatal and retinal anomalies in the context of chromosomopathies and some mono−/oligogenic syndromes are reported associated with Hirschsprung disease the role of inactivating RET mutations in these cases is not clarified. Case presentation We report on a dysmorphic newborn with cleft palate and palatal synechia, who showed intestinal obstruction after 24 h of life. Transient ileostomy and surgical biopsies were performed to diagnose aganglionosis of the colon and last ileal loop. No chromosomal anomalies or copy number variations were found. We identified a paternal heterozygous germline mutation c.1852 T > C, which results in the substitution of cysteine by arginine in the RET-receptor tyrosine kinase (p.C618R mutation). There was no family history of Hirschsprung disease, but the father underwent surgery for medullary thyroid carcinoma and was affected by retinal dystrophy. Conclusions The occurrence of Hirschsprung disease and carcinoma shows how a single mutation may be responsible for adverse effects: gain and loss of function of the same receptor. Furthermore, it would be interesting to study its dual role in face and retina embryology, and to extend targeted investigations of RET hotspots in these developmental abnormalities to facilitate counselling, follow-up, and tumor prevention. Complex surgical procedures and genetic testing as well as socio-economic impact are a challenge for familiar compliance.

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CASE REPORT: RARE FORM OF HIRSCHPRUNG’S DISEASE

10.35988/sm-hs.2020.118 ◽

2020 ◽

Vol 30 (5) ◽

pp. 82-84

Author(s):

Ilja Skalskis

Keyword(s):

Down Syndrome ◽

Case Report ◽

Clinical Symptoms ◽

Hirschsprung Disease ◽

Distal Colon ◽

Total Colonic Aganglionosis ◽

Sphincter Function ◽

Anal Sphincter Function ◽

History Of ◽

High Index Of Suspicion

Hirschsprung disease (HD) is a developmental disorder characterized by the absence of ganglia in the distal colon, resulting in a functional obstruction. Incidence of total colonic aganglionosis (TCA) is 1 in 500 000 and it accounts for 5-10% of all cases of HD. HD should be suspected in patients with typical clinical symptoms and a high index of suspicion is appropriate for infants with a predisposing condition such as Down Syndrome (DS), or for those with a family history of HD. The treatment of choice for HD is surgical, such as Swenson, Soave, and Duhamel procedures. The goals are to resect the affected segment of the colon, bring the normal ganglionic bowel down close to the anus, and preserve internal anal sphincter function. We present a clinical case report of TCA in a child with Down syndrome (DS) and review of literature.

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Pathogenic STX3 variants affecting the retinal and intestinal transcripts cause an early-onset severe retinal dystrophy in microvillus inclusion disease subjects

Human Genetics ◽

10.1007/s00439-021-02284-1 ◽

2021 ◽

Author(s):

Andreas R. Janecke ◽

Xiaoqin Liu ◽

Rüdiger Adam ◽

Sumanth Punuru ◽

Arne Viestenz ◽

...

Keyword(s):

Early Onset ◽

Single Nucleotide Polymorphism Array ◽

Outer Nuclear Layer ◽

Retinal Dystrophy ◽

Geographic Origin ◽

Retinal Disease ◽

Homozygosity Mapping ◽

Rod Photoreceptor ◽

Loss Of Function ◽

Knockout Mouse Model

AbstractBiallelic STX3 variants were previously reported in five individuals with the severe congenital enteropathy, microvillus inclusion disease (MVID). Here, we provide a significant extension of the phenotypic spectrum caused by STX3 variants. We report ten individuals of diverse geographic origin with biallelic STX3 loss-of-function variants, identified through exome sequencing, single-nucleotide polymorphism array-based homozygosity mapping, and international collaboration. The evaluated individuals all presented with MVID. Eight individuals also displayed early-onset severe retinal dystrophy, i.e., syndromic—intestinal and retinal—disease. These individuals harbored STX3 variants that affected both the retinal and intestinal STX3 transcripts, whereas STX3 variants affected only the intestinal transcript in individuals with solitary MVID. That STX3 is essential for retinal photoreceptor survival was confirmed by the creation of a rod photoreceptor-specific STX3 knockout mouse model which revealed a time-dependent reduction in the number of rod photoreceptors, thinning of the outer nuclear layer, and the eventual loss of both rod and cone photoreceptors. Together, our results provide a link between STX3 loss-of-function variants and a human retinal dystrophy. Depending on the genomic site of a human loss-of-function STX3 variant, it can cause MVID, the novel intestinal-retinal syndrome reported here or, hypothetically, an isolated retinal dystrophy.

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Resistance to miltefosine results from amplification of the RTA3 floppase or inactivation of flippases in Candida parapsilosis

10.1101/2021.12.16.473093 ◽

2021 ◽

Author(s):

Sean Bergin ◽

Fang Zhao ◽

Adam P Ryan ◽

Carolin A Müller ◽

Conrad A Nieduszynski ◽

...

Keyword(s):

Plasma Membrane ◽

Copy Number ◽

Candida Parapsilosis ◽

Copy Number Variations ◽

Loss Of Function ◽

Adaptive Laboratory Evolution ◽

Pathogenic Yeast ◽

Lipid Asymmetry ◽

Evolution Experiment ◽

Almost All

Flippases and floppases are two classes of proteins that have opposing functions in the maintenance of lipid asymmetry of the plasma membrane. Flippases translocate lipids from the exoplasmic leaflet to the cytosolic leaflet, and floppases act in the opposite direction. Phosphatidylcholine (PC) is a major component of the eukaryotic plasma membrane and is asymmetrically distributed, being more abundant in the exoplasmic leaflet. Here we show that gene amplification of a putative PC floppase or double disruption of two PC flippases in the pathogenic yeast Candida parapsilosis results in resistance to miltefosine, an alkylphosphocholine drug that affects PC metabolism that has recently been granted orphan drug designation approval by the US FDA for treatment of invasive candidiasis. We analysed the genomes of 170 C. parapsilosis isolates and found that 107 of them have copy number variations (CNVs) at the RTA3 gene. RTA3 encodes a putative PC floppase whose deletion is known to increase the inward translocation of PC in Candida albicans. RTA3 copy number ranges from 2 to >40 across the C. parapsilosis isolates. Interestingly, 16 distinct CNVs with unique endpoints were identified, and phylogenetic analysis shows that almost all of them have originated only once. We found that increased copy number of RTA3 correlates with miltefosine resistance. Additionally, we conducted an adaptive laboratory evolution experiment in which two C. parapsilosis isolates were cultured in increasing concentrations of miltefosine over 26 days. Two genes, CPAR2_303950 and CPAR2_102700, gained homozygous protein-disrupting mutations in the evolved strains and code for putative PC flippases homologous to S. cerevisiae DNF1. Our results indicate that alteration of lipid asymmetry across the plasma membrane is a key mechanism of miltefosine resistance. We also find that C. parapsilosis is likely to gain resistance to miltefosine rapidly, because many isolates carry loss-of-function alleles in one of the flippase genes.

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Loss of CEP162 function at the primary cilium delays ciliogenesis and causes retinal ciliopathy in humans

10.1101/2021.11.23.469779 ◽

2021 ◽

Author(s):

Nafisa Nuzhat ◽

Kristof Van Schil ◽

Sandra Liakopoulos ◽

Miriam Bauwens ◽

Alfredo Dueñas Rey ◽

...

Keyword(s):

Transition Zone ◽

Primary Cilium ◽

Outer Segment ◽

Retinal Dystrophy ◽

Mrna Levels ◽

Loss Of Function ◽

Photoreceptor Outer Segment ◽

Zone Formation ◽

Mother Centriole

Ciliopathies often comprise retinal degeneration since the photoreceptor outer segment is an adapted primary cilium. CEP162 is a distal end centriolar protein required for proper transition zone assembly during ciliogenesis and whose loss causes ciliopathy in zebrafish. CEP162 has so far not been implicated in human disease. Here, we identified a homozygous CEP162 frameshift variant, c.1935dupA (p.(E646R*5)), in retinitis pigmentosa patients from two unrelated Moroccan families, likely representing a founder allele. We found that even though mRNA levels were reduced, the truncated CEP162-E646R*5 protein was expressed and localized to the mitotic spindle during mitosis, but not at the basal body of the cilium. In CEP162 knockdown cells, expression of the truncated CEP162-E646R*5 protein is unable to restore ciliation indicating its loss of function at the cilium. In patient fibroblasts, cilia overcome the absence of CEP162 from the primary cilium by delaying ciliogenesis through the persistence of CP110 at the mother centriole. The patient fibroblasts are ultimately able to extend some abnormally long cilia that are missing key transition zone components. Defective transition zone formation likely disproportionately affects the long-living ciliary outer segment of photoreceptors resulting in retinal dystrophy. CEP162 is expressed in human retina, and we show that wild-type CEP162, but not truncated CEP162-E646R*5, specifically localizes to the distal end of centrioles of mouse photoreceptor cilia. Together, our genetic, cell-based, and in vivo modeling establish that CEP162 deficiency causes retinal ciliopathy in humans.

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Total Colonic Aganglionosis: Case Report, Practical Diagnostic Approach and Pitfalls

Archives of Pathology & Laboratory Medicine ◽

10.5858/2010-0279-cr.1 ◽

2010 ◽

Vol 134 (10) ◽

pp. 1467-1473 ◽

Cited By ~ 3

Author(s):

Raja Rabah

Keyword(s):

Transition Zone ◽

Ganglion Cells ◽

Hirschsprung Disease ◽

Rectal Biopsy ◽

Nerve Fibers ◽

Submucosal Plexus ◽

Total Colonic Aganglionosis ◽

Biopsy Specimens ◽

Suction Rectal Biopsy ◽

Acetylcholinesterase Staining

Abstract Hirschsprung disease remains a challenging diagnosis for many pathologists. The disease is characterized by a lack of ganglion cells in the myenteric and submucosal plexus, associated with increased numbers of acetylcholinesterase-positive nerve fibers. Hypertrophic nerve fibers are present in most but not all patients. Total colonic aganglionosis (TCA) is an uncommon form of Hirschsprung disease with clinical, histologic, and genetic differences and is even more difficult to diagnose and manage. This case illustrates some of the difficulties frequently faced by the pathologists dealing with total colonic aganglionosis. Suction rectal biopsy specimens often lack significant nerve hypertrophy and positive acetylcholinesterase staining, which aid in the diagnosis. Pathologists have to depend mainly on the lack of ganglion cells in adequate submucosa to establish the diagnosis. Transition zone is often long in total colonic aganglionosis and interpretation of frozen sections can be difficult. The presence of several uniformly distributed clusters of mature ganglion cells and lack of nerve hypertrophy are required to avoid connections at the transition zone.

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Novel mutations in the 3-box motif of the BACK domain of KLHL7 associated with nonsyndromic autosomal dominant retinitis pigmentosa

Orphanet Journal of Rare Diseases ◽

10.1186/s13023-019-1275-2 ◽

2019 ◽

Vol 14 (1) ◽

Cited By ~ 2

Author(s):

Jin Kyun Oh ◽

Jose Ronaldo Lima de Carvalho ◽

Young Joo Sun ◽

Sara Ragi ◽

Jing Yang ◽

...

Keyword(s):

Retinitis Pigmentosa ◽

Autosomal Dominant ◽

Fundus Autofluorescence ◽

Retinal Dystrophy ◽

Protein Modeling ◽

Fundus Photography ◽

Imaging Biomarkers ◽

Loss Of Function ◽

Gene Panel Testing ◽

Sd Oct

Abstract Background Mutations in the Kelch-like protein 7 (KLHL7) represent a recently described and, to date, poorly characterized etiology of inherited retinal dystrophy. Dominant mutations in KLHL7 are a cause of isolated, non-syndromic retinitis pigmentosa (RP). In contrast, recessive loss-of-function mutations are known to cause Crisponi or Bohring-Opitz like cold induced sweating syndrome-3 (BOS-3). In this study, the phenotype and progression of five unrelated patients with KLHL7 mediated autosomal dominant RP (adRP) are characterized. Clinical evaluation of these patients involved a complete ophthalmic exam, full-field electroretinography (ffERG), and imaging, including fundus photography, spectral domain optical coherence tomography (SD-OCT), short wavelength fundus autofluorescence (SW-AF), and near-infrared fundus autofluorescence (NIR-AF). Molecular diagnoses were performed using whole-exome sequencing or gene panel testing. Disease progression was monitored in three patients with available data for a mean follow up time of 4.5 ± 2.9 years. Protein modeling was performed for all variants found in this study in addition to those documented in the literature for recessive loss-of-function alleles causing Crisponi or Bohring-Opitz like cold-induced sweating syndrome. Results Genetic testing in three patients identified two novel variants within the 3-box motif of the BACK domain: c.472 T > C:p.(Cys158Arg) and c.433A > T:p.(Asn145Tyr). Clinical imaging demonstrated hyperautofluorescent ring formation on both SW-AF and NIR-AF in three patients, with diffuse peripheral and peripapillary atrophy seen in all but one case. SD-OCT demonstrated a phenotypic spectrum, from parafoveal atrophy of the outer retina with foveal sparing to widespread retinal thinning and loss of photoreceptors. Incidence of cystoid macular edema was high with four of five patients affected. Protein modeling of dominant alleles versus recessive loss-of-function alleles showed dominant alleles localized to the BTB and BACK domains while recessive alleles were found in the Kelch domain. Conclusions We report the phenotype in five patients with KLHL7 mediated adRP, two novel coding variants, and imaging biomarkers using SW-AF and NIR-AF. These findings may influence future gene-based therapies for adRP and pave the way for mechanistic studies that elucidate the pathogenesis of KLHL7-mediated RP.

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Loss-of-function mutation in the X-linked TBX22 promoter disrupts an ETS-1 binding site and leads to cleft palate

Human Genetics ◽

10.1007/s00439-014-1503-8 ◽

2014 ◽

Vol 134 (2) ◽

pp. 147-158 ◽

Cited By ~ 10

Author(s):

Xiazhou Fu ◽

Yibin Cheng ◽

Jia Yuan ◽

Chunhua Huang ◽

Hanhua Cheng ◽

...

Keyword(s):

Cleft Palate ◽

Binding Site ◽

Loss Of Function

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Bi-allelic GAD1 variants cause a neonatal onset syndromic developmental and epileptic encephalopathy

Brain ◽

10.1093/brain/awaa085 ◽

2020 ◽

Vol 143 (5) ◽

pp. 1447-1461 ◽

Cited By ~ 3

Author(s):

Nicolas Chatron ◽

Felicitas Becker ◽

Heba Morsy ◽

Miriam Schmidts ◽

Katia Hardies ◽

...

Keyword(s):

Cleft Palate ◽

Epileptic Encephalopathy ◽

Allelic Loss ◽

Loss Of Function ◽

Seizure Onset ◽

Joint Contractures ◽

Epileptic Encephalopathies ◽

Genomic Technologies ◽

Pes Equinovarus ◽

Modern Genomic

Abstract Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing the phenotype of the knockout Gad1−/− mouse model. Four patients died before 4 years of age. GAD1 encodes the glutamate decarboxylase enzyme GAD67, a critical actor of the γ-aminobutyric acid (GABA) metabolism as it catalyses the decarboxylation of glutamic acid to form GABA. Our findings evoke a novel syndrome related to GAD67 deficiency, characterized by the unique association of developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele.

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