scholarly journals ABNORMAL LYMPHATIC PHENOTYPE IN A CRISPR MOUSE MODEL OF THE HUMAN LYMPHEDEMA-CAUSING CONNEXIN47 R260C POINT MUTATION

Lymphology ◽  
2021 ◽  
Vol 54 (2) ◽  
Author(s):  
D.J. Mustacich ◽  
R.I. Kylat ◽  
M.J. Bernas ◽  
R.J. Myles ◽  
J.A. Jones ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Lymphatic Vessels ◽  
Fold Increase ◽  
Clinical Findings ◽  
Blue Dye ◽  
Missense Mutations ◽  
Regional Lymph Nodes ◽  
Clinical Model ◽  
Mouse Mutants ◽  
Primary Lymphedema

Connexin proteins form gap junctions controlling exchange of ions and small molecules between cells and play an important role in movement of lymph within lymphatic vessels. Connexin47 (CX47) is highly expressed in lymphatic endothelial cells and CX47 missense mutations, i.e., R260C, cosegregate with primary lymphedema in humans. However, studies utilizing CX47 knockout mice have failed to demonstrate any lymphatic anomalies. To unravel the lymphatic consequences of expressing a mutant CX47 protein, we used CRISPR technology to create a mouse carrying a Cx47 missense mutation (Cx47R259C) equivalent to the human CX47R260C missense mutation associated with human primary lymphedema. Intradermal Evans Blue dye injection identified a 2-fold increase in regional lymph nodes in homozygous Cx47R259C mice compared to wildtype, particularly in the jugular region (4.8 ± 0.4 and 2.0 ± 0.0, respectively, p<0.01). Associated lymphatic channels were increased in Cx47R259C mice and mesenteric lymph reflux occurred in homozygous Cx47R259C mice but not in wildtype. Contractility of superficial cervical lymphatics, assessed by pressure myography, was reduced in homozygous Cx47R259C mice compared to wildtype. In conclusion, our data are the first to demonstrate a role for the Cx47 protein in lymphatic anatomy and function. This phenotype is similar to that found with other valve deficient mouse mutants, e.g., in Foxc2. Of significance, this study is the first to use CRISPR technology to develop a pre-clinical model of primary lymphedema and demonstrates the importance of distinguishing between lack of and presence of mutant protein when developing clinically relevant animal models for translation of pre-clinical findings.

scholarly journals Characterization of ANGPT2 mutations associated with primary lymphedema

2020 ◽  
Vol 12 (560) ◽  
pp. eaax8013 ◽  
Author(s):  
Veli-Matti Leppänen ◽  
Pascal Brouillard ◽  
Emilia A. Korhonen ◽  
Tuomas Sipilä ◽  
Sawan Kumar Jha ◽  
...  
Keyword(s):  
De Novo ◽  
Vascular System ◽  
Lymphatic Vessels ◽  
Mouse Skin ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Missense Mutations ◽  
Activation Mechanisms ◽  
Primary Lymphedema ◽  
Negative Effect

Primary lymphedema is caused by developmental and functional defects of the lymphatic vascular system that result in accumulation of protein-rich fluid in tissues, resulting in edema. The 28 currently known genes causing primary lymphedema can explain <30% of cases. Angiopoietin 1 (ANGPT1) and ANGPT2 function via the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor–like domains 1 and 2) receptor complex and α5β1 integrin to form an endothelial cell signaling pathway that is critical for blood and lymphatic vessel formation and remodeling during embryonic development, as well as for homeostasis of the mature vasculature. By screening a cohort of 543 individuals affected by primary lymphedema, we identified one heterozygous de novo ANGPT2 whole-gene deletion and four heterozygous ANGPT2 missense mutations. Functional analyses revealed three missense mutations that resulted in decreased ANGPT2 secretion and inhibited the secretion of wild-type (WT)–ANGPT2, suggesting that they have a dominant-negative effect on ANGPT2 signaling. WT-ANGPT2 and soluble mutants T299M and N304K activated TIE1 and TIE2 in an autocrine assay in human lymphatic endothelial cells. Molecular modeling and biophysical studies showed that amino-terminally truncated ANGPT subunits formed asymmetrical homodimers that bound TIE2 in a 2:1 ratio. The T299M mutant, located in the dimerization interphase, showed reduced integrin α5 binding, and its expression in mouse skin promoted hyperplasia and dilation of cutaneous lymphatic vessels. These results demonstrate that primary lymphedema can be associated with ANGPT2 mutations and provide insights into TIE1 and TIE2 activation mechanisms.

scholarly journals Loss-of-function germline GATA2 mutations in patients with MDS/AML or MonoMAC syndrome and primary lymphedema reveal a key role for GATA2 in the lymphatic vasculature

Blood ◽  
2012 ◽  
Vol 119 (5) ◽  
pp. 1283-1291 ◽  
Author(s):  
Jan Kazenwadel ◽  
Genevieve A. Secker ◽  
Yajuan J. Liu ◽  
Jill A. Rosenfeld ◽  
Robert S. Wildin ◽  
...  
Keyword(s):  
Lymphatic Vessels ◽  
Splice Site Mutation ◽  
Missense Mutations ◽  
Loss Of Function ◽  
Site Mutation ◽  
Predisposing Factor ◽  
Large Deletions ◽  
Expression Of Genes ◽  
Primary Lymphedema ◽  
Lymphatic Vasculature

Abstract Recent work has established that heterozygous germline GATA2 mutations predispose carriers to familial myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML), “MonoMAC” syndrome, and DCML deficiency. Here, we describe a previously unreported MDS family carrying a missense GATA2 mutation (p.Thr354Met), one patient with MDS/AML carrying a frameshift GATA2 mutation (p.Leu332Thrfs*53), another with MDS harboring a GATA2 splice site mutation, and 3 patients exhibiting MDS or MDS/AML who have large deletions encompassing the GATA2 locus. Intriguingly, 2 MDS/AML or “MonoMAC” syndrome patients with GATA2 deletions and one with a frameshift mutation also have primary lymphedema. Primary lymphedema occurs as a result of aberrations in the development and/or function of lymphatic vessels, spurring us to investigate whether GATA2 plays a role in the lymphatic vasculature. We demonstrate here that GATA2 protein is present at high levels in lymphatic vessel valves and that GATA2 controls the expression of genes important for programming lymphatic valve development. Our data expand the phenotypes associated with germline GATA2 mutations to include predisposition to primary lymphedema and suggest that complete haploinsufficiency or loss of function of GATA2, rather than missense mutations, is the key predisposing factor for lymphedema onset. Moreover, we reveal a crucial role for GATA2 in lymphatic vascular development.

A Novel Mutation Glyl672→Arg in Type 2A and a Homozygous Mutation in Type 2B von Willebrand Disease

1996 ◽  
Vol 76 (02) ◽  
pp. 253-257 ◽  
Author(s):  
Takeshi Hagiwara ◽  
Hiroshi Inaba ◽  
Shinichi Yoshida ◽  
Keiko Nagaizumi ◽  
Morio Arai ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Novel Mutation ◽  
Point Mutations ◽  
Japanese Patients ◽  
Von Willebrand Disease ◽  
Homozygous Mutation ◽  
Missense Mutations ◽  
Reaction Products ◽  
Type 3 ◽  
Von Willebrand

SummaryGenetic materials from 16 unrelated Japanese patients with von Willebrand disease (vWD) were analyzed for mutations. Exon 28 of the von Willebrand factor (vWF) gene, where point mutations have been found most frequent, was screened by various restriction-enzyme analyses. Six patients were observed to have abnormal restriction patterns. By sequence analyses of the polymerase chain-reaction products, we identified a homozygous R1308C missense mutation in a patient with type 2B vWD; R1597W, R1597Q, G1609R and G1672R missense mutations in five patients with type 2A; and a G1659ter nonsense mutation in a patient with type 3 vWD. The G1672R was a novel missense mutation of the carboxyl-terminal end of the A2 domain. In addition, we detected an A/C polymorphism at nucleotide 4915 with HaeIII. There was no particular linkage disequilibrium of the A/C polymorphism, either with the G/A polymorphism at nucleotide 4391 detected with Hphl or with the C/T at 4891 detected with BstEll.

Technetium-99m-based Radiopharmaceuticals in Sentinel Lymph Node Biopsy: Gynecologic Oncology Perspective

2018 ◽  
Vol 24 (15) ◽  
pp. 1652-1675 ◽  
Author(s):  
Kamil Zalewski ◽  
Malgorzata Benke ◽  
Bartlomiej Mirocha ◽  
Jakub Radziszewski ◽  
Magdalena Chechlinska ◽  
...  
Keyword(s):  
Half Life ◽  
Intraoperative Imaging ◽  
Gynecologic Oncology ◽  
Lymphatic Vessels ◽  
Diagnostic Procedures ◽  
Medical Personnel ◽  
Biological Properties ◽  
Lymph Node Biopsy ◽  
Regional Lymph Nodes ◽  
Extensive Lymphadenectomy

Technetium (99mTc)-radiolabeled colloids are popular tracers used to map lymphatic vessels and regional lymph nodes (LNs). The regional LN status is a significant determinant of cancer stage and patient prognosis, and strongly influences treatment. Regional LN dissection has become a part of surgical treatment. However, not all patients with LN involvement benefit from extensive lymphadenectomy in terms of prolonged survival. Moreover, overtreatment of patients with localized disease carries the unnecessary risk of complications. It is believed that sentinel LN biopsy (SLNB) allows to assess the involvement of the most representative LN of the lymphatic basin and to decide on radical LN dissection.99mTc is an easily available radionuclide emitting gamma rays. The value of 99mTc for diagnostic procedures is associated with its relatively short half-life that makes it safe both for patients and medical personnel. A colloid presenting specific physical and biological properties, including optimal particle size, is a carrier for the radionuclide. When administered at the tumor site, a radiocolloid is absorbed by the lymphatics, and the first LN that it gets trapped in is referred to as the sentinel LN (SLN). The radiopharmaceutical must reach the SLN relatively quickly, but its storage within the SLN, and the radionuclide’s half-life must be long enough to enable intraoperative imaging and evaluation. SLNB is currently the gold standard in breast cancer and malignant melanoma diagnosis, and is under extensive investigation in gynecological cancers. Here, we provide a historical perspective of the SLN concept and the clinical relevance of SLNB in gynecologic oncology. Moreover, we review the technical aspects of the application of 99mTc-based radiopharmaceuticals in lymphoscintigraphy and intraoperative lymphatic mapping.

scholarly journals Epidemiological and clinical characteristics of immunocompromised patients infected with Pneumocystis jirovecii in a twelve-year retrospective study from Norway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Stine Grønseth ◽  
Tormod Rogne ◽  
Raisa Hannula ◽  
Bjørn Olav Åsvold ◽  
Jan Egil Afset ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Fold Increase ◽  
Epidemiological Data ◽  
Opportunistic Pathogen ◽  
Incidence Rates ◽  
Clinical Findings ◽  
Pneumocystis Jirovecii ◽  
Common Denominator ◽  
Study Population ◽  
Cardinal Symptoms

Abstract Background Pneumocystis pneumonia (PCP) severely menaces modern chemotherapy and immunosuppression. Detailed description of the epidemiology of Pneumocystis jirovecii today is needed to identify candidates for PCP-prophylaxis. Methods We performed a 12-year retrospective study of patients with P. jirovecii detected by polymerase chain reaction in Central Norway. In total, 297 patients were included. Comprehensive biological, clinical and epidemiological data were abstracted from patients’ medical records. Regional incidence rates and testing trends were also assessed. Results From 2007 to 2017 we found a 3.3-fold increase in testing for P. jirovecii accompanied by a 1.8-fold increase in positive results. Simultaneously, regional incidence rates doubled from 5.0 cases per 100,000 person years to 10.8. A majority of the study population had predisposing conditions other than human immunodeficiency virus (HIV). Hematological (36.0%) and solid cancers (25.3%) dominated. Preceding corticosteroids were a common denominator for 72.1%. Most patients (74.4%) presented with at least two cardinal symptoms; cough, dyspnea or fever. Main clinical findings were hypoxia, cytopenias and radiological features consistent with PCP. A total of 88 (29.6%) patients required intensive care and 121 (40.7%) suffered at least one complication. In-hospital mortality was 21.5%. Three patients (1.0%) had received prophylaxis. Conclusions P. jirovecii is re-emerging; likely due to increasing immunosuppressants use. This opportunistic pathogen threatens the life of heterogenous non-HIV immunosuppressed populations currently at growth. Corticosteroids seem to be a major risk factor. A strategy to increase prophylaxis is called for.

scholarly journals Incidence of the CHEK2 Germline Mutation and Its Impact on Clinicopathological Features, Treatment Responses, and Disease Course in Patients with Papillary Thyroid Carcinoma

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 470
Author(s):  
Danuta Gąsior-Perczak ◽  
Artur Kowalik ◽  
Krzysztof Gruszczyński ◽  
Agnieszka Walczyk ◽  
Monika Siołek ◽  
...  
Keyword(s):  
Papillary Thyroid Carcinoma ◽  
Thyroid Carcinoma ◽  
Missense Mutation ◽  
Vascular Invasion ◽  
Germline Mutations ◽  
Primary Treatment ◽  
Clinicopathological Characteristics ◽  
Missense Mutations ◽  
Papillary Thyroid ◽  
Treatment Responses

The CHEK2 gene is involved in the repair of damaged DNA. CHEK2 germline mutations impair this repair mechanism, causing genomic instability and increasing the risk of various cancers, including papillary thyroid carcinoma (PTC). Here, we asked whether CHEK2 germline mutations predict a worse clinical course for PTC. The study included 1547 unselected PTC patients (1358 women and 189 men) treated at a single center. The relationship between mutation status and clinicopathological characteristics, treatment responses, and disease outcome was assessed. CHEK2 mutations were found in 240 (15.5%) of patients. A CHEK2 I157T missense mutation was found in 12.3%, and CHEK2 truncating mutations (IVS2 + 1G > A, del5395, 1100delC) were found in 2.8%. The truncating mutations were more common in women (p = 0.038), and were associated with vascular invasion (OR, 6.91; p < 0.0001) and intermediate or high initial risk (OR, 1.92; p = 0.0481) in multivariate analysis. No significant differences in these parameters were observed in patients with the I157T missense mutation. In conclusion, the CHEK2 truncating mutations were associated with vascular invasion and with intermediate and high initial risk of recurrence/persistence. Neither the truncating nor the missense mutations were associated with worse primary treatment response and outcome of the disease.

An intronic variant disrupts mRNA splicing and causes FGFR3-related skeletal dysplasia

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ting Xu ◽  
Liang Shi ◽  
Weiqian Dai ◽  
Xuefan Gu ◽  
Yongguo Yu ◽  
...  
Keyword(s):  
De Novo ◽  
Clinical Findings ◽  
Recurrent Mutation ◽  
Mrna Splicing ◽  
Additional Patient ◽  
Missense Mutations ◽  
Splicing Variant ◽  
Amino Acid Insertion ◽  
Whole Exome ◽  
Minigene Assay

Abstract Objectives Achondroplasia and hypochondroplasia are the most common forms of disproportionate short stature, of which the vast majority of cases can be attributed to the hotspot missense mutations in the gene FGFR3. Here we presented cases with a novel cryptic splicing variant of FGFR3 gene and aimed to interrogate the variant pathogenicity. Case presentaiton In whole exome sequencing of two patients with hypochondroplasia-like features, a de novo intronic variant c.1075 + 95C>G was identified, predicted to alter mRNA splicing. Minigene assay showed that this intronic variant caused retention of a 90-nucleotide segment of intron 8 in mRNA, resulting in a 30-amino acid insertion at the extracellular domain of the protein. This is the first likely pathogenic splicing variant identified in the FGFR3 gene and was detected in one additional patient among 26 genetically unresolved patients. Conclustions Our results strongly suggest that c.1075 + 95C>G is a recurrent mutation and should be included in genetic testing of FGFR3 especially for those patients with equivocal clinical findings and no exonic mutations identified.

scholarly journals Biochemical Characterization of the GBA2 c.1780G>C Missense Mutation in Lymphoblastoid Cells from Patients with Spastic Ataxia

2018 ◽  
Vol 19 (10) ◽  
pp. 3099 ◽  
Author(s):  
Anna Malekkou ◽  
Maura Samarani ◽  
Anthi Drousiotou ◽  
Christina Votsi ◽  
Sandro Sonnino ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Autosomal Recessive ◽  
Biochemical Characterization ◽  
Fold Increase ◽  
Loss Of Function ◽  
Spastic Paraplegia ◽  
Spastic Ataxia ◽  
Autosomal Recessive Cerebellar Ataxia ◽  
Compensatory Effect

The GBA2 gene encodes the non-lysosomal glucosylceramidase (NLGase), an enzyme that catalyzes the conversion of glucosylceramide (GlcCer) to ceramide and glucose. Mutations in GBA2 have been associated with the development of neurological disorders such as autosomal recessive cerebellar ataxia, hereditary spastic paraplegia, and Marinesco-Sjogren-Like Syndrome. Our group has previously identified the GBA2 c.1780G>C [p.Asp594His] missense mutation, in a Cypriot consanguineous family with spastic ataxia. In this study, we carried out a biochemical characterization of lymphoblastoid cell lines (LCLs) derived from three patients of this family. We found that the mutation strongly reduce NLGase activity both intracellularly and at the plasma membrane level. Additionally, we observed a two-fold increase of GlcCer content in LCLs derived from patients compared to controls, with the C16 lipid being the most abundant GlcCer species. Moreover, we showed that there is an apparent compensatory effect between NLGase and the lysosomal glucosylceramidase (GCase), since we found that the activity of GCase was three-fold higher in LCLs derived from patients compared to controls. We conclude that the c.1780G>C mutation results in NLGase loss of function with abolishment of the enzymatic activity and accumulation of GlcCer accompanied by a compensatory increase in GCase.

scholarly journals FLT4 Mutations Are Associated with Segmental Lymphatic Dysfunction and Initial Lymphatic Aplasia in Patients with Milroy Disease

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1611
Author(s):  
Ningfei Liu ◽  
Minzhe Gao
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Clinical Signs ◽  
Lymphatic Vessels ◽  
Growth Factor Receptor ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Missense Mutations ◽  
History Of ◽  
Endothelial Growth Factor

This study explored mutations in the Fms-related tyrosine kinase 4/vascular endothelial growth factor receptor 3 gene (FLT4) and lymphatic defects in patients with Milroy disease (MD). Twenty-nine patients with lower limb lymphedema were enrolled. Sixteen patients had a familial history of MD, while 13 patients exhibited sporadic MD. Clinical signs, FLT4 mutations, indocyanine green (ICG) lymphography findings, and skin tissue immunohistochemical staining results were evaluated. Twenty-eight variants in FLT4 were identified. Twelve of these have previously been reported, while 16 are novel. Of the 28 variants, 26 are missense mutations, and the remaining two comprise a splicing mutation and a non-frame shift mutation. Twenty-five variants are located in the intracellular protein tyrosine kinase domain; three are located in the extracellular immunoglobulin domain. Substantially delayed contrast-enhanced tortuous lymphatic vessels were visualized to the ankle or knee level in 15 of 23 patients who underwent ICG lymphography. No initial lymphatic vessels were visualized in skin specimens from four patients who did not exhibit lymphatic vessels during imaging analyses. No specific variant was identified in relation to the unique clinical phenotype. Segmental dysfunction of lymphatic vessels and initial lymphatic aplasia are present in MD patients with FLT4 mutations.

scholarly journals Identification of a novel pathogenic missense mutation in PRPF31 using whole exome sequencing: a case report

2018 ◽  
Vol 103 (6) ◽  
pp. 761-767 ◽  
Author(s):  
Laura Bryant ◽  
Olga Lozynska ◽  
Anson Marsh ◽  
Tyler E Papp ◽  
Lucas van Gorder ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Missense Mutation ◽  
Whole Exome Sequencing ◽  
Protein Trafficking ◽  
Protein Misfolding ◽  
Autosomal Dominant ◽  
Null Alleles ◽  
Incomplete Penetrance ◽  
Missense Mutations ◽  
Whole Exome

BackgroundVariants in PRPF31, which encodes pre-mRNA processing factor 31 homolog, are known to cause autosomal-dominant retinitis pigmentosa (adRP) with incomplete penetrance. However, the majority of mutations cause null alleles, with only two proven pathogenic missense mutations. We identified a novel missense mutation in PRPF31 in a family with adRP.MethodsWe performed whole exome sequencing to identify possible pathogenic mutations in the proband of a family with adRP. Available affected family members had a full ophthalmological evaluation including kinetic and two-colour dark adapted static perimetry, electroretinography and multimodal imaging of the retina. Two patients had evaluations covering nearly 20 years. We carried out segregation analysis of the probable mutation, PRPF31 c.590T>C. We evaluated the cellular localisation of the PRPF31 variant (p.Leu197Pro) compared with the wildtype PRPF31 protein.ResultsPRPF31 c.590T>C segregated with the disease in this four-generation autosomal dominant pedigree. There was intrafamilial variability in disease severity. Nyctalopia and mid-peripheral scotomas presented from the second to the fourth decade of life. There was severe rod >cone dysfunction. Visual acuity (VA) was relatively intact and was maintained until later in life, although with marked interocular asymmetries. Laboratory studies showed that the mutant PRPF31 protein (p.Leu197Pro) does not localise to the nucleus, unlike the wildtype PRPF31 protein. Instead, mutant protein resulted in punctate localisation to the cytoplasm.Conclusionsc.590T>C is a novel pathogenic variant in PRPF31 causing adRP with incomplete penetrance. Disease may be due to protein misfolding and associated abnormal protein trafficking to the nucleus.

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