scholarly journals Three Novel EPCAM Variants Causing Tufting Enteropathy in Three Families

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 503
Author(s):  
Hasret Ayyıldız Civan ◽  
Coleen Leitner ◽  
Iris Östreicher ◽  
Anna-Maria Schneider ◽  
Malte Cremer ◽  
...  
Keyword(s):  
Missense Variant ◽  
High Rate ◽  
Compound Heterozygous ◽  
Sequencing Data ◽  
Phenotype Correlation ◽  
Intractable Diarrhea ◽  
Exon 1 ◽  
Duodenal Biopsies ◽  
Compound Heterozygous State ◽  
Related Mortality

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.

scholarly journals FANCA Gene Mutations in North African Fanconi Anemia Patients

2021 ◽  
Vol 12 ◽  
Author(s):  
Abir Ben Haj Ali ◽  
Olfa Messaoud ◽  
Sahar Elouej ◽  
Faten Talmoudi ◽  
Wiem Ayed ◽  
...  
Keyword(s):  
Fanconi Anemia ◽  
Genetic Disorders ◽  
Gene Mutations ◽  
Missense Variant ◽  
High Rate ◽  
Compound Heterozygous ◽  
North African ◽  
Founder Mutations ◽  
Molecular Approaches ◽  
Number Of Patients

Populations in North Africa (NA) are characterized by a high rate of consanguinity. Consequently, the proportion of founder mutations might be higher than expected and could be a major cause for the high prevalence of recessive genetic disorders like Fanconi anemia (FA). We report clinical, cytogenetic, and molecular characterization of FANCA in 29 North African FA patients from Tunisia, Libya, and Algeria. Cytogenetic tests revealed high rates of spontaneous chromosome breakages for all patients except two of them. FANCA molecular analysis was performed using three different molecular approaches which allowed us to identify causal mutations as homozygous or compound heterozygous forms. It included a nonsense mutation (c.2749C > T; p.Arg917Ter), one reported missense mutation (c.1304G > A; p.Arg435His), a novel missense variant (c.1258G > A; p.Asp409Glu), and the FANCA most common reported mutation (c.3788_3790delTCT; p.Phe1263del). Furthermore, three founder mutations were identified in 86.7% of the 22 Tunisian patients: (1) a deletion of exon 15, in 36.4% patients (8/22); (2), a deletion of exons 4 and 5 in 23% (5/22) and (3) an intronic mutation c.2222 + 166G > A, in 27.3% (6/22). Despite the relatively small number of patients studied, our results depict the mutational landscape of FA among NA populations and it should be taken into consideration for appropriate genetic counseling.

Molecular basis of ciliary defects caused by compound heterozygous IFT144/WDR19 mutations found in cranioectodermal dysplasia

2021 ◽  
Author(s):  
Yamato Ishida ◽  
Takuya Kobayashi ◽  
Shuhei Chiba ◽  
Yohei Katoh ◽  
Kazuhisa Nakayama
Keyword(s):  
Protein Trafficking ◽  
Primary Cilia ◽  
Intraflagellar Transport ◽  
Missense Variant ◽  
Cellular Level ◽  
Compound Heterozygous ◽  
Hypomorphic Allele ◽  
Genes Encoding ◽  
Specific Proteins ◽  
Compound Heterozygous Mutations

Abstract Primary cilia contain specific proteins to achieve their functions as cellular antennae. Ciliary protein trafficking is mediated by the intraflagellar transport (IFT) machinery containing the IFT-A and IFT-B complexes. Mutations in genes encoding the IFT-A subunits (IFT43, IFT121/WDR35, IFT122, IFT139/TTC21B, IFT140, and IFT144/WDR19) often result in skeletal ciliopathies, including cranioectodermal dysplasia (CED). We here characterized the molecular and cellular defects of CED caused by compound heterozygous mutations in IFT144 [the missense variant IFT144(L710S) and the nonsense variant IFT144(R1103*)]. These two variants were distinct with regard to their interactions with other IFT-A subunits and with the IFT-B complex. When exogenously expressed in IFT144-knockout (KO) cells, IFT144(L710S) as well as IFT144(WT) rescued both moderately compromised ciliogenesis and the abnormal localization of ciliary proteins. As the homozygous IFT144(L710S) mutation was found to cause autosomal recessive retinitis pigmentosa, IFT144(L710S) is likely to be hypomorphic at the cellular level. In striking contrast, the exogenous expression of IFT144(R1103*) in IFT144-KO cells exacerbated the ciliogenesis defects. The expression of IFT144(R1103*) together with IFT144(WT) restored the abnormal phenotypes of IFT144-KO cells. However, the coexpression of IFT144(R1103*) with the hypomorphic IFT144(L710S) variant in IFT144-KO cells, which mimics the genotype of compound heterozygous CED patients, resulted in severe ciliogenesis defects. Taken together, these observations demonstrate that compound heterozygous mutations in IFT144 cause severe ciliary defects via a complicated mechanism, where one allele can cause severe ciliary defects when combined with a hypomorphic allele.

scholarly journals Biallelic novel mutations of the COL27A1 gene in a patient with Steel syndrome

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jong Seop Kim ◽  
Hyoungseok Jeon ◽  
Hyeran Lee ◽  
Jung Min Ko ◽  
Yonghwan Kim ◽  
...  
Keyword(s):  
Hip Dysplasia ◽  
Large Deletion ◽  
Compound Heterozygous ◽  
Radial Head Dislocation ◽  
Sequencing Data ◽  
Novel Mutations ◽  
Exome Sequencing Data ◽  
Whole Exome ◽  
Whole Exome Sequencing Data ◽  
Carpal Coalition

AbstractAn 11-year-old Korean boy presented with short stature, hip dysplasia, radial head dislocation, carpal coalition, genu valgum, and fixed patellar dislocation and was clinically diagnosed with Steel syndrome. Scrutinizing the trio whole-exome sequencing data revealed novel compound heterozygous mutations of COL27A1 (c.[4229_4233dup]; [3718_5436del], p.[Gly1412Argfs*157];[Gly1240_Lys1812del]) in the proband, which were inherited from heterozygous parents. The maternal mutation was a large deletion encompassing exons 38–60, which was challenging to detect.

scholarly journals UNC13B variants associated with partial epilepsy with favourable outcome

Brain ◽  
2021 ◽  
Author(s):  
Jie Wang ◽  
Jing-Da Qiao ◽  
Xiao-Rong Liu ◽  
De-Tian Liu ◽  
Yan-Hui Chen ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Brain Mri ◽  
Missense Variant ◽  
Febrile Seizures ◽  
Favourable Outcome ◽  
Partial Epilepsy ◽  
Favorable Outcome ◽  
Compound Heterozygous ◽  
Developmental Abnormalities ◽  
Seizure Rate

Abstract The unc-13 homolog B (UNC13B) gene encodes a presynaptic protein, mammalian uncoordinated 13–2 (Munc13-2), that is highly expressed in the brain—predominantly in the cerebral cortex—and plays an essential role in synaptic vesicle priming and fusion, potentially affecting neuronal excitability. However, the functional significance of UNC13B mutation in human disease is not known. In this study we screened for novel genetic variants in a cohort of 446 unrelated cases (families) with partial epilepsy without acquired causes by trio-based whole-exome sequencing. UNC13B variants were identified in 12 individuals affected by partial epilepsy and/or febrile seizures from eight unrelated families. The eight probands all had focal seizures and focal discharges in EEG recordings, including two patients who experienced frequent daily seizures and one who showed abnormalities in the hippocampus by brain MRI; however, all of the patients showed favorable outcome without intellectual or developmental abnormalities. The identified UNC13B variants included one nonsense variant, two variants at or around a splice site, one compound heterozygous missense variant, and four missense variants that cosegregated in the families. The frequency of UNC13B variants identified in the present study was significantly higher than that in a control cohort of Han Chinese and controls of the East Asian and all populations in the Genome Aggregation Database. Computational modeling, including hydrogen bond and docking analyses, suggested that the variants lead to functional impairment. In Drosophila, seizure rate and duration were increased by Unc13b knockdown compared to wild-type flies, but these effects were less pronounced than in sodium voltage-gated channel alpha subunit 1 (Scn1a) knockdown Drosophila. Electrophysiologic recordings showed that excitatory neurons in Unc13b-deficient flies exhibited increased excitability. These results suggest that UNC13B is potentially associated with epilepsy. The frequent daily seizures and hippocampal abnormalities but ultimately favorable outcome under antiepileptic therapy in our patients indicate that partial epilepsy caused by UNC13B variant is a clinically manageable condition.

619 HIGH DISCOVERY RATE OF GASTRODUODENAL EOSINOPHILIA BUT NOT EOSINOPHILIC ESOPHAGITIS IN PATIENTS WITH CHRONIC GASTROINTESTINAL SYMPTOMS

2021 ◽  
Vol 34 (Supplement_1) ◽  
Author(s):  
Nicholas Talley ◽  
Amol Kamboj ◽  
William Chey ◽  
Henrik Rasmussen ◽  
Brian Lacy ◽  
...  
Keyword(s):  
Eosinophilic Esophagitis ◽  
Gastrointestinal Symptoms ◽  
High Rate ◽  
Systematic Evaluation ◽  
Tissue Eosinophilia ◽  
Severity Scores ◽  
Gi Symptoms ◽  
Multi Center Study ◽  
Loss Of Appetite ◽  
Duodenal Biopsies

Abstract   Although the prevalence of eosinophilic gastrointestinal disorders (EGIDs) is increasing, there is evidence that eosinophilic gastritis and/or duodenitis (EG/EoD) are underdiagnosed. Patients with EG/EoD often present with chronic, non-specific gastrointestinal (GI) symptoms, similar to patients with functional GI disorders. We hypothesized that systematic evaluation, including multiple esophageal, gastric and duodenal biopsies, of patients with chronic GI symptoms might reveal a high rate of gastroduodenal eosinophila, with or without eosinophilic esophagitis (EoE). Methods We performed a prospective multi-center study of patients with non-specific GI symptoms for ≥6 months, from 20 sites. Patients completed a questionnaire assessing abdominal pain, abdominal cramping, early satiety, bloating, nausea, vomiting, diarrhea, and loss of appetite. Those with daily average symptom severity scores ≥3/10 for any single symptom underwent esophagogastroduodenoscopy (EGD) with collection of 4 esophageal (EoE), 8 gastric, and 4 duodenal biopsies, analyzed by central pathologists. Histologic criteria for EoE was ≥15eos/hpf in ≥1 esophageal site and for EG/EoD was peak eosinophil counts ≥30/hpf in ≥5 gastric hpfs and/or 3 duodenal hpfs—criteria used in randomized trials. Results Of 556 patients screened, 405 (73%) met symptom criteria and underwent EGD; 181 patients (45%, mean age 45, 73% female) who underwent EGD met the histologic criteria for EG/EoD, and of these, 7% also had EoE diagnosed. Overall 2% met histologic criteria for EoE alone. Of patients who met the histologic criteria for EG/EoD, 93% were previously diagnosed with gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), or functional dyspepsia (FD) (Figure 1). The average duration of GI symptoms in the screened population as well as those that met histologic criteria for EG/EoD was 11 years. Conclusion Forty-five percent of patients with moderate-to-severe GI symptoms who underwent EGD met histologic criteria for EG/EoD. Over 90% of these patients had previously been diagnosed with GERD, IBS, and/or FD, and had minimal overlap with EoE. EGD with systematic gastroduodenal biopsies, and intentional evaluation for tissue eosinophilia, should be performed in patients with chronic GI symptoms. Accurate diagnosis of EG/EoD is required for appropriate, targeted treatment and improved outcomes of patients with moderate-to-severe GI symptoms.

scholarly journals Hypolipidemia associated with inactivation of TM6SF2 is due to decreased VLDL-lipids secretion

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
F Luo ◽  
E Smagris ◽  
J A Fletcher ◽  
J C Cohen ◽  
H H Hobbs
Keyword(s):  
Plasma Lipid ◽  
Microscopic Analysis ◽  
Missense Variant ◽  
Cell Fractionation ◽  
Loss Of Function ◽  
Lipid Levels ◽  
Funding Sources ◽  
Golgi Compartment ◽  
Exon 1 ◽  
Biochemical Analyses

Abstract Background A missense variant in Transmembrane 6 Superfamily Member 2 [TM6SF2 (E167K)] is associated with reduced plasma lipid levels and protection from coronary atherosclerosis. The substitution of lysine for glutamate at residue 167 is associated with a marked decrease in TM6SF2 protein expression, consistent with a loss-of-function mutation. However the biological role of TM6SF2 is not known, and the mechanism(s) responsible for the hypolipidemia associated with mutation gene has not been fully defined. To elucidate the pathological mechanism for the hypolipidemia associated with TM6SF2 deficiency, we inactivated Tm6sf2 in mice and rats. Methods Tm6sf2−/− mice were generated as described previously. Two lines of Tm6sf2−/− rats with different frameshift mutations in exon 1 were generated using CRISPR/Cas9 technology. Primary hepatocytes were isolated from WT and Tm6sf2−/− mice for microscopy. Rats were fasted 16 or 4 hours and tissues were collected on ice for cell fractionation, and in liquid nitrogen for biochemical analyses. Frozen samples were stored at −80°C for subsequent analyses. Result In both mice and rats, inactivation of Tm6sf2 recapitulated the phenotype of humans with the E167K substitution: steatosis, reduced plasma lipid levels, and transaminitis. The phenotype was readily apparent in animals fed chow diets. Both species had reduced secretion of VLDL-TG, as determined by TRITON WR1399 injection, with no decrease in secretion of ApoB. Experiments in isolated perfused livers from WT and Tm6sf2−/− mice confirmed that the decreased TG secretion observed in intact animals reflected reduced TG secretion from the liver. Lipidomic analysis of the liver perfusates by by LC-MS indicated that secretion of cholesteryl esters, and phospholipids was also decreased in the KO animals. Taken together, these findings are consistent with a role for TM6SF2 in lipidation of ApoB-containing lipoproteins. To further elucidate the function of TM6SF2, we used fluorescence microscopy and cell fractionation to determine the subcellular localization of the protein. Microscopic analysis showed that TM6SF2 co-localized with ER and Golgi markers, but cell fractionation studies indicated that the protein is located primarily in the smooth ER. The ratio of TG to ApoB was lower in Golgi fractions from TM6sf2−/− rats than in corresponding fractions from WT animals. Conclusions Since the sequela of TM6SF2 inactivation are already apparent in the Golgi, we speculate that TM6SF2 promotes lipidation of VLDL in a pre-Golgi compartment. We are currently performing additional studies to further define the specific mechanism whereby TM6SF2 promotes lipidation of ApoB-containing lipoproteins. FUNDunding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Institutes of Health

scholarly journals Mechanisms of Congenital Myasthenia Caused by Three Mutations in the COLQ Gene

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaona Luo ◽  
Chunmei Wang ◽  
Longlong Lin ◽  
Fang Yuan ◽  
Simei Wang ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Neuromuscular Junctions ◽  
Three Dimensional ◽  
Missense Variant ◽  
Homozygous Deletion ◽  
Dimensional Structure ◽  
Compound Heterozygous ◽  
Splicing Mutation ◽  
Gene Encoding ◽  
Congenital Myasthenia

The gene encoding collagen like tail subunit of asymmetric acetylcholinesterase (COLQ) is responsible for the transcription of three strands of collagen of acetylcholinesterase, which is attached to the endplate of neuromuscular junctions. Mutations in the COLQ gene are inherited in an autosomal-recessive manner and can lead to type V congenital myasthenia syndrome (CMS), which manifests as decreased muscle strength at birth or shortly after birth, respiratory failure, restricted eye movements, drooping of eyelids, and difficulty swallowing. Here we reported three variants within COLQ in two unrelated children with CMS. An intronic variant (c.393+1G>A) and a novel missense variant (p.Q381P) were identified as compound heterozygous in a 13-month-old boy, with the parents being carriers of each. An intragenic deletion including exons 14 and 15 was found in a homozygous state in a 12-year-old boy. We studied the relative expression of the COLQ and AChE gene in the probands' families, performed three-dimensional protein structural analysis, and analyzed the conservation of the missense mutation c.1142A>C (p.Q381P). The splicing mutation c.393+1G>A was found to affect the normal splicing of COLQ exon 5, resulting in a 27-bp deletion. The missense mutation c.1142A>C (p.Q381P) was located in a conserved position in different species. We found that homozygous deletion of COLQ exons 14–15 resulted in a 241-bp deletion, which decreased the number of amino acids and caused a frameshift translation. COLQ expression was significantly lower in the probands than in the probands' parents and siblings, while AChE expression was significantly higher. Moreover, the mutations were found to cause significant differences in the predicted three-dimensional structure of the protein. The splicing mutation c.393+1G>A, missense mutation c.1A>C (p.Q381P), and COLQ exon 14–15 deletion could cause CMS.

Novel compound heterozygous EPG5 mutations consisted with a missense mutation and a microduplication in the exon 1 region identified in a Japanese patient with Vici syndrome

2018 ◽  
Vol 176 (12) ◽  
pp. 2803-2807 ◽  
Author(s):  
Shino Shimada ◽  
Kyoko Hirasawa ◽  
Akiko Takeshita ◽  
Hidetsugu Nakatsukasa ◽  
Keiko Yamamoto-Shimojima ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Japanese Patient ◽  
Compound Heterozygous ◽  
Exon 1
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