scholarly journals Gonadal Dysgenesis Without Adrenal Insufficiency in a 46, XY Patient Heterozygous for the Nonsense C16X Mutation: A Case of SF1 Haploinsufficiency

2004 ◽  
Vol 89 (10) ◽  
pp. 4829-4832 ◽  
Author(s):  
Delphine Mallet ◽  
Patricia Bretones ◽  
Laurence Michel-Calemard ◽  
Frederique Dijoud ◽  
Michel David ◽  
...  

Abstract Targeted disruption of the orphan nuclear receptor SF1 results in the absence of adrenals and gonads, establishing that this transcription factor is implicated in gonadal determination and adrenal development. Four human SF1 gene mutations have been described to date: three (G35E, R92Q, R255L) were responsible for adrenal insufficiency associated with a gonadal dysgenesis in two 46, XY individuals, one (8 bp deletion in exon 6) resulted in gonadal dysgenesis without adrenal insufficiency. We identified a new heterozygous SF1 gene mutation, C16X, in a 46, XY patient showing gonadal dysgenesis with normal adrenal function: low basal levels of AMH and testosterone (T), weak T response to hCG, hypoplastic testes with abundant seminiferous tubules but rare germ cells. This mutation causes premature termination of translation and should abolish all SF1 activity. Therefore haploinsufficiency could explain the deleterious effect of this mutation in our patient suggesting that testis development is more SF1 dose-dependant than adrenal development. Although the same mechanism explains the deleterious effects of SF1 missense mutations, recent studies have demonstrated an additional dominant negative effect. These data suggest that heterozygous mutation impaired adrenal development only if the two mechanisms, gene dosage and dominant negative effects occur.

2018 ◽  
Vol 38 (4) ◽  
Author(s):  
Lijun Xu ◽  
Qianqian Pang ◽  
Yan Jiang ◽  
Ou Wang ◽  
Mei Li ◽  
...  

Hypophosphatasia (HPP) is a rare inherited disorder characterized by defective bone and/or dental mineralization, and decreased serum alkaline phosphatase (ALP) activity. ALPL, the only gene related with HPP, encodes tissue non-specific ALP (TNSALP). Few studies were carried out in ALPL gene mutations in the Chinese population with HPP. The purpose of the present study is to elucidate the clinical and genetic characteristics of HPP in five unrelated Chinese families and two sporadic patients. Ten clinically diagnosed HPP patients from five unrelated Chinese families and two sporadic patients and fifty healthy controls were genetically investigated. All 12 exons and exon–intron boundaries of the ALPL gene were amplified by PCR and directly sequenced. The laboratory and radiological investigations were conducted simultaneously in these HPP ten patients. A 3D model of the TNSALP was used to predict the dominant negative effect of identified missense mutations. Three odonto, three childhood, and four adult types of HPP were clinically diagnosed. Ten mutations were identified in five unrelated Chinese families and two sporadic patients, including eight missense mutations and two frameshift mutations. Of which, four were novel: one frameshift mutation (p.R138Pfsx45); three missense mutations (p.C201R, p.V459A, p.C497S). No identical mutations and any other new ALPL mutations were found in unrelated 50 healthy controls. Our study demonstrated that the ALPL gene mutations are responsible for HPP in these Chinese families. These findings will be useful for clinicians to improve understanding of this heritable bone disorder.


2018 ◽  
Author(s):  
Sarah J. Fletcher ◽  
Vera P. Pisareva ◽  
Abdullah Khan ◽  
Andrew Tcherepanov ◽  
Neil V. Morgan ◽  
...  

ABSTRACTPlatelets are anucleate and mostly ribosome-free cells within the bloodstream, derived from megakaryocytes within bone marrow and crucial for cessation of bleeding at sites of injury. Inherited thrombocytopenias are a group of disorders characterized by alow platelet count and are frequently associated with excessive bleeding. SLFN14 is one of the most recently discovered genes linked to inherited thrombocytopenia where several heterozygous missense mutations in SLFN14 were identified to cause defective megakaryocyte maturation and platelet dysfunction. Yet, SLFN14 was recently described as a ribosome-associated protein resulting in rRNA and ribosome-bound mRNA degradation in rabbit reticulocytes. To unveil the cellular function of SLFN14 and the link between SLFN14 and thrombocytopenia, we examined SLFN14 (WT/mutants) in in vitro models. Here, we show that all SLFN14 variants co-localize with ribosomes and mediate rRNA endonucleolytic degradation and ribosome clearance. Compare dto SLFN14 WT, expression of mutants is dramatically reduced as a result of post-translational degradation due to partial misfolding of the protein. Moreover, all SLFN14 variants tend to form oligomers. These findings could explain the dominant negative effect of heterozygous mutation on SLFN14 expression in patients’ platelets. Overall we suggest that SLFN14 could be involved in ribosome degradation during platelet formation and maturation.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 67-67
Author(s):  
Rosemary E Gale ◽  
Katarina Lamb ◽  
Christopher Allen ◽  
Dima El-Sharkawi ◽  
Cassandra Stowe ◽  
...  

Abstract DNMT3A mutations (DNMT3AMUT) are recurrent in AML. They predominate in patients with intermediate-risk (IR) cytogenetics and are often co-incident with FLT3ITD and NPM1MUT. Their prognostic impact is unclear. Most reports suggest they are associated with a worse outcome, but a large study including 1060 younger adult IR patients found that DNMT3AMUT had no significant impact on survival endpoints. Variable results have also been reported for different FLT3/NPM1 subgroups. Missense mutations at R882 in exon 23 occur in ≈65% of patients, but other missense and truncation mutations occur throughout the gene, mainly in exons 13-23. There is limited information on the prognostic impact of the different mutations, although they may have differing functional consequences. We therefore screened exons 13-23 in DNA samples from 914 younger adult AML patients (median age 43 years) with IR cytogenetics treated on UK MRC trials and evaluated outcome according to type of DNMT3Amutation. Overall, 278 mutations were detected in 272 (30%) patients; 175 (64%) had R882 missense mutations, 59 (22%) other missense mutations, 35 (13%) truncations or in-frame deletions; 3 (1%) had 2 mutations of differing types. Median R882 mutant level in 172 mutated cases was 47% (range 15-85%), consistent with a heterozygous mutation in most cells. Patients with DNMT3AMUT were significantly older than those with DNMT3A wild-type (DNMT3AWT) (P<.0001), more likely to be female (P=.004), have a higher presenting WBC (P<.0001), and a normal rather than abnormal karyotype (P<.0001). The presence of DNMT3AMUT positively correlated with FLT3ITD (P=.0003) and NPM1MUT (P<.0001) and negatively correlated with CEBPAMUT (P<.0001). Patients with R882 mutations had significantly higher WBC (P=.005) and correlation with NPM1MUT (P=.01) than non-R882 mutated patients; non-R882 missense mutated patients had higher WBC (P=.05) and non-significant higher co-incidence with FLT3ITD than those with truncations. Presence of DNMT3AMUT was associated with a poorer prognosis, but this difference was only seen if the results were analyzed separately according to NPM1 genotype, where DNMT3AMUT was associated with higher cumulative incidence of relapse (CIR) than DNMT3AWT in cases with NPM1MUT (49% vs 40%, P=.01) and NPM1WT (61% vs 58%, P=.5) genotype. Similarly, DNMT3AMUT patients had worse overall survival (OS) than DNMT3AWT patients with NPM1MUT (38% vs 50%, P=.008) and NPM1WT (15% vs 25%, P=.09) genotype. This statistical anomaly is an example of Simpson’s paradox. It results from the strong co-incidence of DNMT3A and NPM1 mutations with opposing prognostic associations that mask the effect seen separately when the groups are combined. Although the differences were smaller for NPM1WT cases, tests for heterogeneity showed that the impact of a DNMT3A mutation did not differ between NPM1MUT and NPM1WT for either CIR or OS, nor between the 4 genotypes defined by the combination of NPM1 and FLT3ITD genotypes. In multivariable analysis including age, WBC, NPM1 and FLT3ITD, DNMT3AMUT was a significant adverse risk factor for CIR (HR=1.27, CI=1.01-1.61; P=.04), and showed a trend for being adverse for OS (HR=1.19, CI=.98-1.45; P=.08). When outcome was considered according to the type of mutation (R882, other missense or truncations), for the NPM1MUT genotype cases CIR was highest in R882 and other missense cases (51%, 50%) and truncation cases were similar to DNMT3AWT (35%, 40%). For NPM1WT, CIR was highest in R882 cases (76%), similar in other missense and DNMT3AWT cases (55%, 58%) and lowest in truncation cases (40%). Consistent with this data, for NPM1MUT genotype, OS was lowest in R882 and other missense cases (35%, 38%), better in DNMT3AWT (50%) and highest in truncation cases (57%). For NPM1WT, OS was lowest in R882 cases (11%), and similar in DNMT3AWT, other missense and truncation cases (25%, 21%, 18% respectively). These data suggest that screening cannot be limited to the hotspot R882 mutations and that cases with missense mutations should be treated as poor risk, including those patients currently considered as favorable risk such as NPM1MUTFLT3WT. Conversely, truncation mutations have a different functional impact from missense mutations, more likely to result in haploinsufficiency than a dominant-negative effect, and these cases should be considered as equivalent to DNMT3AWT for prognostication and selection of therapy in 1st remission. Disclosures No relevant conflicts of interest to declare.


2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Seung Won Choi ◽  
Yeri Lee ◽  
Kayoung Shin ◽  
Harim Koo ◽  
Donggeon Kim ◽  
...  

AbstractPTEN is one of the most frequently altered tumor suppressor genes in malignant tumors. The dominant-negative effect of PTEN alteration suggests that the aberrant function of PTEN mutation might be more disastrous than deletion, the most frequent genomic event in glioblastoma (GBM). This study aimed to understand the functional properties of various PTEN missense mutations and to investigate their clinical relevance. The genomic landscape of PTEN alteration was analyzed using the Samsung Medical Center GBM cohort and validated via The Cancer Genome Atlas dataset. Several hotspot mutations were identified, and their subcellular distributions and phenotypes were evaluated. We established a library of cancer cell lines that overexpress these mutant proteins using the U87MG and patient-derived cell models lacking functional PTEN. PTEN mutations were categorized into two major subsets: missense mutations in the phosphatase domain and truncal mutations in the C2 domain. We determined the subcellular compartmentalization of four mutant proteins (H93Y, C124S, R130Q, and R173C) from the former group and found that they had distinct localizations; those associated with invasive phenotypes (‘edge mutations’) localized to the cell periphery, while the R173C mutant localized to the nucleus. Invasive phenotypes derived from edge substitutions were unaffected by an anti-PI3K/Akt agent but were disrupted by microtubule inhibitors. PTEN mutations exhibit distinct functional properties regarding their subcellular localization. Further, some missense mutations (‘edge mutations’) in the phosphatase domain caused enhanced invasiveness associated with dysfunctional cytoskeletal assembly, thus suggesting it to be a potent therapeutic target.


2002 ◽  
pp. 649-656 ◽  
Author(s):  
J Rutishauser ◽  
P Kopp ◽  
MB Gaskill ◽  
TJ Kotlar ◽  
GL Robertson

OBJECTIVE: To test further the hypothesis that autosomal dominant neurohypophyseal diabetes insipidus (adFNDI) is caused by heterozygous mutations in the vasopressin-neurophysin II (AVP-NPII) gene that exert a dominant negative effect by producing a precursor that misfolds, accumulates and eventually destroys the neurosecretory neurons. METHODS: Antidiuretic function, magnetic resonance imaging (MRI) of the posterior pituitary and AVP-NPII gene analysis were performed in 10 affected members of three unreported families with adFNDI. RESULTS: As in previously studied patients, adFNDI apparently manifested after birth, was due to a partial or severe deficiency of AVP, and was associated with absence or diminution of the hyperintense MRI signal normally emitted by the posterior pituitary, and with a heterozygous mutation in the AVP-NPII gene. In family A, a transition 275G-->A, which predicts replacement of cysteine 92 by tyrosine (C92Y), was found in the index patient, but not in either parent, indicating that it arose de novo. The six affected members of family B had a transversion 160G-->C, which predicts replacement of glycine 54 by arginine (G54R). It appeared de novo in the oldest affected member, and was transmitted in a dominant manner. In family C, six of 15 living affected members were tested and all had a novel transition, 313T-->C, which predicts replacement of cysteine 105 by arginine (C105R). It, too, was transmitted in a dominant manner. As in other patients with adFNDI, the amino acids replaced by the mutations in these three families are known to be particularly important for correct and efficient folding of the precursor. CONCLUSIONS: These findings are consistent with the malfolding/toxicity hypothesis underlying the pathogenesis of adFNDI. Moreover, they illustrate the value of genetic analysis in all patients who develop idiopathic diabetes insipidus in childhood, even if no other family members are affected.


2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
Y Yamamoto ◽  
T Makiyama ◽  
Y Wuriyanghai ◽  
H Kohjitani ◽  
J Gao ◽  
...  

Abstract Background Calmodulin (CaM) is a ubiquitous Ca2+ sensor molecule encoded by three distinct calmodulin genes, CALM1–3, and has an important role for cardiac ion channel function. Recently, heterozygous missense mutations in CALM genes were reported to cause a new category of life-threatening genetic arrhythmias such as long-QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT), which is called as “calmodulinopathy”. The patients with calmodulinopathy show poor prognosis and there is no effective treatment for them. Purpose Considering the dominant-negative effect of mutant calmodulin proteins produced by heterozygous missense mutations in CALMs, we aimed to prove the concept of antisense-based therapy to treat calmodulinopathy using human iPS cell-derived cardiomyocyte (hiPSC-CM) model. Methods We designed multiple locked nucleic acid (LNA) gapmer-antisense oligonucleotides (ASOs) targeting CALM2 and analyzed the silencing efficiency and toxicity in cultured cells to select the most potent ASO. Using CMs differentiated from hiPSCs which were generated form a 12-year-old boy with LQTS carrying a heterozygous CALM2-N98S mutation, CALM2 expression and action potentials (APs) were analyzed to evaluate the efficacy of ASOs. Results We identified several ASOs which reduced CALM2 expression without affecting cell viability in human cultured cells (HepG2) (ASO 50 nM, n=2; Figure 1A). Considering further experiments in vivo mouse model, we investigated the CALM2 silencing activity in mouse cultured cells (3T3-L1) without transfection (free-uptake) (ASO 1 μM, n=2; †ASOs have homologous sequence between human and mouse; Figure B). After free-uptake CALM2 silencing analysis in 3T3-L1 cells, we identified that ASO #2 has the most potent CALM2 silencing activity and low cytotoxicity (Figure 1B). ASO #2 effectively reduced CALM2 expression even in hiPSC-CMs (ASO(−): n=3, lipofection: n=4, free-uptake: n=3; P&lt;0.05; Figure 1C). In action potential recordings, we demonstrated that ASO #2 ameliorated prolonged AP durations (APD90) in N98S-hiPSC-CMs at 0.5 Hz pacing (ASO(−): 666±123 ms (n=7), lipofection: 329±21 ms (n=8), free-uptake: 388±34 ms (n=12); P&lt;0.05; Figure 1D). Conclusion Our results using patient-derived hiPSC-CM model suggest that ASO-based therapy might be a promising strategy for the treatment of calmodulinopathy. Figure 1 Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Nissan Chemical Corporation


2020 ◽  
pp. jbc.RA120.014749
Author(s):  
Xin Tong ◽  
Dandan Xu ◽  
Rama K. Mishra ◽  
Ryan D Jones ◽  
Leyu Sun ◽  
...  

The TP53 gene is the most frequently mutated gene in human cancers, and the majority of TP53 mutations are missense mutations. As a result, these mutant p53 (mutp53) either directly lose wild-type p53 (wtp53) tumor suppressor function or exhibit a dominant negative effect over wtp53. In addition, some mutp53 have acquired new oncogenic function (gain of function). Therefore, targeting mutp53 for its degradation, may serve as a promising strategy for cancer prevention and therapy. Based on our previous finding that farnesylated DNAJA1 is a crucial chaperone in maintaining mutp53 stabilization, and by using an in silico approach, we built 3-D homology models of human DNAJA1 and mutp53R175H proteins, identified the interacting pocket in the DNAJA1-mutp53R175H complex, and found one critical druggable small molecule binding  site in the DNAJA1 glycine/phenylalanine rich region. We confirmed that the interacting pocket in the DNAJA1-mutp53R175H complex was crucial for stabilizing mutp53R175H using a site-directed mutagenesis approach. We further screened a drug-like library to identify a promising small molecule hit (GY1-22) against the interacting pocket in DNAJA1-mutp53R175H complex. The GY1-22 compound displayed an effective activity against DNAJA1-mutp53R175H complex. Treatment with GY1-22 significantly reduced mutp53 protein levels, enhanced Waf1p21 expression, suppressed cyclin D1 expression, and inhibited mutp53-driven pancreatic cancer growth both in vitro and in vivo. Together, our results indicate that the interacting pocket in the DNAJA1-mutp53R175H complex is critical for mutp53’s stability and oncogenic function, and DNAJA1 is a robust therapeutic target for developing the efficient small molecule inhibitors against oncogenic mutp53.


2015 ◽  
Author(s):  
Jessica X Chong ◽  
Margaret J McMillin ◽  
Kathryn M Shively ◽  
Anita E Beck ◽  
Colby T Marvin ◽  
...  

Freeman-Sheldon syndrome, or distal arthrogryposis type 2A (DA2A), is an autosomal dominant condition caused by mutations in MYH3 and characterized by multiple congenital contractures of the face and limbs and normal cognitive development. We identified a subset of five simplex cases putatively diagnosed with “DA2A with severe neurological abnormalities” in which the proband had Congenital Contractures of the LImbs and FAce, Hypotonia, and global Developmental Delay often resulting in early death, a unique condition that we now refer to as CLIFAHDD syndrome. Exome sequencing identified missense mutations in sodium leak channel, nonselective (NALCN) in four families with CLIFAHDD syndrome. Using molecular inversion probes to screen NALCN in a cohort of 202 DA cases as well as concurrent exome sequencing of six other DA cases revealed NALCN mutations in ten additional families with “atypical” forms of DA. All fourteen mutations were missense variants predicted to alter amino acid residues in or near the S5 and S6 pore-forming segments of NALCN, highlighting the functional importance of these segments. In vitro functional studies demonstrated that mutant NALCN nearly abolished the expression of wildtype NALCN, suggesting that mutations that cause CLIFAHDD syndrome have a dominant negative effect. In contrast, homozygosity for mutations in other regions of NALCN has been reported in three families with an autosomal recessive condition characterized mainly by hypotonia and severe intellectual disability. Accordingly, mutations in NALCN can cause either a recessive or dominant condition with varied though overlapping phenotypic features perhaps depending on the type of mutation and affected protein domain(s).


2021 ◽  
Author(s):  
Julian Koch ◽  
Alexander Lang ◽  
Patcharawalai Whongsiri ◽  
Wolfgang A. Schulz ◽  
Michele Janine Hoffmann ◽  
...  

Abstract Background KDM6A, encoding a histone demethylase, is one of the top ten mutated epigenetic cancer genes. The effect of mutations on its structure and function are however poorly characterized. Methods Database search identified nonsense and missense mutations in the N-terminal TPR motifs and the C-terminal, catalytic JmjC domain, but also in the intrinsically disordered region connecting both well-structured domains. KDM6A variants with cancer-derived mutations were generated using site directed mutagenesis and fused to eGFP, which served as an all-in-one affinity and fluorescence tag to study demethylase activity by an ELISA based assay in vitro, complex assembly by Co-immunoprecipitation and localization by microscopy in cellulo. Results Independent of the mutation and demethylase activity, all KDM6A variants were detectable in the nucleus. KDM6A truncations displayed changes in complex assemblies: affecting (1) known interactions with the COMPASS complex component RBBP5 and (2) KDM6A-DNA associated assemblies with the nucleolar protein Nucleophosmin. Furthermore, we observed a severe cellular phenotype characterized by multiple acute effects on nuclear integrity, namely, release of nuclear DNA into the cytoplasm, increased level of DNA damage indicators RAD51 and p-γH2A.X, and hence mitosis defects. Conclusion These observations reveal novel effects of pathogenic variants pointing at new specific functions of KDM6A as well as at a dominant negative effect of KDM6A truncation variants. The underlying mechanisms and affected pathways have to be investigated in future research to understand how tumor cells cope with and benefit from KDM6A truncations.


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