A Novel Compound-Heterozygous Epithelial Cell Adhesion Molecule Mutation in Tufting Enteropathy.
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ABSTRACT:
SUBMITTER: Shakhnovich V
PROVIDER: S-EPMC4426084 | biostudies-literature | 2017 Jan
REPOSITORIES: biostudies-literature
Publications
A Novel Compound-Heterozygous Epithelial Cell Adhesion Molecule Mutation in Tufting Enteropathy.
Shakhnovich Valentina V Dinwiddie Darrell D Hildreth Amber A Attard Thomas T Kingsmore Stephen S
Journal of pediatric gastroenterology and nutrition 20170101 1
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Project description:Congenital diarrheal disorders (CDDs) with genetic etiology are uncommon hereditary intestinal diseases characterized by chronic, life-threatening, intractable watery diarrhea that starts in infancy. CDDs can be mechanistically divided into osmotic and secretory diarrhea. Congenital tufting enteropathy (CTE), also known as intestinal epithelial dysplasia, is a type of secretory CDD. CTE is a rare autosomal recessive enteropathy that presents with intractable neonatal-onset diarrhea, intestinal failure, severe malnutrition, and parenteral nutrition dependence. Villous atrophy of the intestinal epithelium, crypt hyperplasia, and irregularity of surface enterocytes are the specific pathological findings of CTE. The small intestine and occasionally the colonic mucosa include focal epithelial tufts. In 2008, Sivagnanam et al. discovered that mutations in the epithelial cell adhesion molecule (EpCAM, MIM# 185535) were the genetic cause of CTE (MIM# 613217). More than a hundred mutations have been reported to date. Furthermore, mutations in the serine peptidase inhibitor Kunitz type 2 (SPINT2, MIM# 605124) have been linked to syndromic CTE. In this study, we report the case of a 17-month-old male infant with congenital diarrhea. Despite extensive etiological workup, no etiology could be established before admission to our center. The patient died 15 hours after being admitted to our center in a metabolically decompensated state, probably due to a delay in admission and diagnosis. Molecular autopsy with exome sequencing revealed a previously reported homozygous missense variant, c.757G>A, in EpCAM, which was confirmed by histopathological examination.
| S-EPMC9679307 | biostudies-literature
Project description:Mutations in the epithelial cell adhesion molecule (EpCAM; CD326) gene are causal for congenital tufting enteropathy (CTE), a disease characterized by intestinal abnormalities resulting in lethal diarrhea in newborns. Why the different mutations all lead to the same disease is not clear. Here, we report that most mutations, including a novel intronic variant, will result in lack of EpCAM's transmembrane domain, whereas two mutations allow transmembrane localization. We find that these mutants are not routed to the plasma membrane, and that truncated mutants are secreted or degraded. Thus, all epcam mutations lead to loss of cell-surface EpCAM, resulting in CTE.
| S-EPMC3674798 | biostudies-literature
Project description:Tufting enteropathy (TE) is caused by recessive EPCAM mutations, and is characterized by intractable diarrhea of congenital onset and disorganization of enterocytes. TE generally requires parenteral nutrition (PN) during childhood or intestinal bowel transplantation. We report three unrelated families with six children with TE. We highlight the high rate of disease-related mortality. We observe adequate weight gain with PN, but low to normal and stunted body length, supporting the recent notion that a short stature might be intrinsic to TE. The diagnosis of TE in the index patients from each family was delayed for months to years, even when clinical data, duodenal biopsies, or exome sequencing data were obtained early on. We identified three novel pathogenic EPCAM variants: a deletion of exon 1 that removes the ATG initiation codon, a missense variant c.326A > G (p.Gln109Arg), and nonsense mutation c.429G > A (p.Trp143*) in a compound heterozygous state with the Mediterranean splice site variant c.556-14A > G (Tyr186Phefs*6). Homozygosity for p.Gln109Arg was associated with absent EPCAM staining, and compound heterozygosity for p.Trp143*/Tyr186Phefs*6 was associated with reduced EPCAM staining in duodenal biopsies; such observations might contribute to a genotype-phenotype correlation in larger cohorts of TE patients. This study extends the clinical and molecular spectrum of TE.
| S-EPMC8232273 | biostudies-literature
Project description:The epithelial cell adhesion molecule gene (EPCAM, previously known as TACSTD1 or TROP1) encodes a membrane-bound protein that is localized to the basolateral membrane of epithelial cells and is overexpressed in some tumors. Biallelic mutations in EPCAM cause congenital tufting enteropathy (CTE), which is a rare chronic diarrheal disorder presenting in infancy. Monoallelic deletions of the 3' end of EPCAM that silence the downstream gene, MSH2, cause a form of Lynch syndrome, which is a cancer predisposition syndrome associated with loss of DNA mismatch repair. Here, we report 13 novel EPCAM mutations from 17 CTE patients from two separate centers, review EPCAM mutations associated with CTE and Lynch syndrome, and structurally model pathogenic missense mutations. Statistical analyses indicate that the c.499dupC (previously reported as c.498insC) frameshift mutation was associated with more severe treatment regimens and greater mortality in CTE, whereas the c.556-14A>G and c.491+1G>A splice site mutations were not correlated with treatments or outcomes significantly different than random simulation. These findings suggest that genotype-phenotype correlations may be useful in contributing to management decisions of CTE patients. Depending on the type and nature of EPCAM mutation, one of two unrelated diseases may occur, CTE or Lynch syndrome.
| S-EPMC6328345 | biostudies-literature
Project description:BackgroundCongenital tufting enteropathy (CTE) is a rare cause of diarrhea in children. However, it can result in early-onset of chronic diarrhea and failure to thrive. Children with this disease have to depend on total parenteral nutrition (TPN), and eventually small intestine transplantation. The epithelial cell adhesion molecule (EPCAM) gene was identified to be associated with CTE. Here, we present a case of an infant with CTE due to a mutation not reported in the literature before.Case summaryA 1-year and 7-mo infant boy exhibited intractable watery diarrhea and mushy stool within 1 wk after birth, for which he had required medical treatment and hospitalization several times. His sister presented similar symptoms and died at the age of two. On admission, his body weight was 5700 g (-4.8SDS) and measured 66 cm (-5.4SDS) in height. Meanwhile, he cannot speak or climb. He exhibited mild anemia, hypocalcemia, hypomagnesemia, and an infection in the upper respiratory tract. Microvilli sparse and vacuolar degeneration of epithelial cells were reported by small intestine biopsy. Whole-exome sequencing showed a novel homozygous splice mutation (c.657+1[IVS6] G>A) in the EPCAM gene. He was treated with TPN and recombinant human growth hormone. After 2 mo, his body weight was up to 8500 g and he has been waiting for small bowel transplantation.ConclusionCTE is rare but fatal. Patients with CTE require rapid diagnosis and therapy to improve their survival.
| S-EPMC7642537 | biostudies-literature
Project description:Oligozoospermia is an important cause of male infertility for which treatment options are limited. Spermatogenesis is complex, and the causes of oligozoospermia remain largely unknown. Because genetic mutations are important factors of oligozoospermia pathogenesis, our study aimed to explore the genetic causes of oligozoospermia. Whole- exome sequencing (WES) was performed on one proband from a Chinese family who was diagnosed with oligozoospermia. The pathogenic mutations were confirmed by Sanger sequencing, and a minigene assay was used to determine the effect of the identified splicing mutation. We identified a novel compound heterozygous mutation in the TDRD9 gene, comprising a splicing mutation (c.1115 + 3A > G) and a frameshift mutation (c.958delC), in the proband; neither of these mutations were found in 50 unrelated healthy people. In addition, a minigene assay demonstrated that the frameshift produced partially truncated protein, and the splicing mutation led to a frameshift mutation and premature termination due to abnormal alternative splicing of TDRD9. These findings indicate that deleterious compound heterozygous mutation in TDRD9 could lead to oligozoospermia, highlighting the crucial role of TDRD9 in spermatogenesis and further clarifying the genetic causes of male infertility resulting from oligozoospermia. Our study expands the spectrum of TDRD9-related phenotypes and provides a new specific target for future genetic counseling.
| S-EPMC11527903 | biostudies-literature
Project description:Harlequin ichthyosis (HI) is the most severe form of autosomal recessive congenital ichthyosis, presenting at birth with distinctive facial features and thick, plate-like scales over the entire body. The abnormal skin barrier predisposes the patient to multiple complications, including dehydration and sepsis. Mortality rates of babies with HI have been greatly reduced since the introduction of systemic retinoid therapy. Mutations in ABCA12 have been found to lead to HI. Most of these mutations are truncation or deletion mutations in the conserved region of the protein, leading to severe loss of ABCA12 function. We report a case of HI caused by a compound heterozygous mutation (a known single nucleotide deletion and a novel single nucleotide substitution) in the ABCA12 gene.
| S-EPMC5775800 | biostudies-literature
Project description:Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable.
| S-EPMC4591836 | biostudies-literature
Project description:Congenital tufting enteropathy (CTE) is a rare autosomal recessive diarrheal disorder presenting in the neonatal period. CTE is characterized by intestinal epithelial cell dysplasia leading to severe malabsorption and significant morbidity and mortality. The pathogenesis and genetics of this disorder are not well understood. The objective of this study was to identify the gene responsible for CTE.A family with 2 children affected with CTE was identified. The affected children are double second cousins providing significant statistical power for linkage. Using Affymetrix 50K single nucleotide polymorphism (SNP) chips, genotyping was performed on only 2 patients and 1 unaffected sibling. Direct DNA sequencing of candidate genes, reverse-transcription polymerase chain reaction, immunohistochemistry, and Western blotting were performed on specimens from patients and controls.SNP homozygosity mapping identified a unique 6.5-Mbp haplotype of homozygous SNPs on chromosome 2p21 where approximately 40 genes are located. Direct sequencing of genes in this region revealed homozygous G>A substitution at the donor splice site of exon 4 in epithelial cell adhesion molecule (EpCAM) of affected patients. Reverse-transcription polymerase chain reaction of duodenal tissue demonstrated a novel alternative splice form with deletion of exon 4 in affected patients. Immunohistochemistry and Western blot of patient intestinal tissue revealed decreased expression of EpCAM. Direct sequencing of EpCAM from 2 additional unrelated patients revealed novel mutations in the gene.Mutations in the gene for EpCAM are responsible for CTE. This information will be used to gain further insight into the molecular mechanisms of this disease.
| S-EPMC2574708 | biostudies-literature
Project description:PurposeMutations in the β-tubulin isotype, TUBB8, can cause female infertility. Although several mutations of TUBB8 have been reported, the full spectrum for guiding genetics counseling still needs to be further explored. Here, we sought to identify novel variants in TUBB8 and their phenotypic effects on microtubule network structure in vitro.MethodsWhole-exome sequence analysis was performed in two families with infertility to detect pathogenic variants, with validation by Sanger sequencing. All gene variants and protein structures were predicted in silico. Cells were transfected with wild-type and mutants, and immunofluorescence analysis was performed to visualize microtubule network changes.ResultsWe detected a novel compound heterozygous mutation, c.915_916delCC (p.Arg306Serfs*21) and c.82C > T (p.His28Tyr), and a benign heterozygous variant c.1286C > T (p.Thr429Met) in TUBB8 in the two families. Female patients with p.Arg306Serfs*21 and p.His28Tyr were infertile with early embryonic developmental arrest. The female patient with p.Thr429Met gave birth to a healthy baby in the second in vitro fertilization frozen embryo transfer cycle. The p.Arg306Serfs*21 mutation was predicted to cause large structural alteration in the TUBB8 protein and was confirmed to produce a truncated and trace protein by western blot analysis. Immunofluorescence analysis of transfected HeLa cells showed that p.Arg306Serfs*21 significantly disrupted microtubule structure.ConclusionsOur findings expand the known mutational spectrum of TUBB8 associated with early embryonic developmental arrest and female infertility.
| S-EPMC10224908 | biostudies-literature