Browsing by Subject "mutation"

Now showing 1 - 8 of 8
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    Evaluation of Genetic Causes of Cardiomyopathy in Childhood
    (Cambridge, 2015-08) Ware, Stephanie M.; Department of Pediatrics, IU School of Medicine
    Cardiomyopathy frequently has a genetic basis. In adults, mutations in genes encoding components of the sarcomere, cytoskeleton, or desmosome are frequent genetic causes of cardiomyopathy. Although children share these causes, ~30% of children have an underlying metabolic, syndromic, or neuromuscular condition causing their cardiomyopathy, making the aetiologies more diverse in children as compared with adults. Although some children present with obvious signs or symptoms of metabolic, syndromic, or neuromuscular disease, other cases may be quite subtle, requiring a high level of suspicion in order to diagnose them. In general, the younger the child, the more extensive the differential. Advantages of identifying the underlying genetic cause of cardiomyopathy in the paediatric population include confirming the diagnosis in ambiguous cases, facilitating appropriate surveillance and management of cardiac and extra-cardiac diseases, providing prognostic information, and establishing the genetic basis in the family, thereby allowing the identification of at-risk relatives and institution of appropriate family screening as indicated. For these reasons, genetic testing is increasingly recognised as standard of care, and guidelines for genetic counselling, testing, and incorporation of family-based risk assessment have been established. Therapies aimed at treating specific genetic aetiologies of cardiomyopathy are emerging and are exciting new developments that require increasingly sophisticated approaches to diagnosis. As genetic testing capabilities continue to expand technically, careful interpretation, knowledgeable clinical utilisation, and appropriate dissemination of genetic information are important and challenging components of clinical care.
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    Merlin immunohistochemistry is useful in diagnosis of tumours within the spectrum of biphasic hyalinizing psammomatous renal cell carcinoma
    (Wiley, 2022-11) Collins, Katrina; Hwang, Michael; Antic, Tatjana; Paintal, Ajit; Argani, Pedram; Matoso, Andres; Gopinath, Arun; Baskovich, Brett; Mehra, Rohit; Williamson, Sean R.; Idrees, Muhammad T.; Barletta, Justine A.; Anderson, William J.; Hirsch, Michelle S.; Hornick , Jason L.; Acosta, Andres M.; Pathology and Laboratory Medicine, School of Medicine
    Aims: Biphasic hyalinizing psammomatous (BHP) renal cell carcinoma (RCC) is a newly described emerging entity within the spectrum of papillary RCC in the WHO 2022 classification. Molecular analyses have discovered that BHP RCC consistently harbour somatic mutations in the neurofibromin 2 (NF2) gene. The NF2 gene product, merlin, is known to primarily function as a tumour suppressor. Merlin protein loss correlates closely with the presence of NF2 mutations in benign and malignant tumours arising in different sites. In the present study we explored the role of merlin immunohistochemistry (IHC) in tumours within the spectrum of BHP RCC to determine the diagnostic utility of this marker. Materials and methods: We performed merlin IHC in 13 BHP RCC, 18 papillary RCC, 10 TFE3-translocation RCC, 15 TFEB-altered RCC (including 13 TFEB-rearranged and 2 TFEB-amplified), and 10 mucinous tubular and spindle cell carcinomas of unknown mutational status. Results: Unequivocal loss of merlin expression in >90% of the tumour cells was observed in 12/13 BHP-RCC (92%), with the remaining tumour demonstrating weak focal cytoplasmic expression in ~10% of the tumour. In contrast, merlin was diffusely or multifocally expressed in all papillary RCC, TFE3-translocation RCC, and TFEB-altered RCC, as well as in 70% of mucinous tubular and spindle carcinomas. Conclusions: In this study, merlin IHC was ~92% sensitive and ~94% specific for BHP RCC. These data suggest that merlin IHC is a reliable surrogate marker for the presence of underlying NF2 gene inactivation, being diagnostically useful to identify BHP RCC.
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    A Missense Variant in PTPN22 is a Risk Factor for Drug-induced Liver Injury
    (Elsevier, 2019) Cirulli, Elizabeth T.; Nicoletti, Paola; Abramson, Karen; Andrade, Raul J.; Bjornsson, Einar S.; Chalasani, Naga; Fontana, Robert J.; Hallberg, Pär; Li, Yi Ju; Lucena, M. Isabel; Long, Nanye; Molokhia, Mariam; Nelson, Matthew R.; Odin, Joseph A.; Pirmohamed, Munir; Rafnar, Thorunn; Serrano, Jose; Stefansson, Kari; Stolz, Andrew; Daly, Ann K.; Aithal, Guruprasad P.; Watkins, Paul B.; Medicine, School of Medicine
    Background & Aims We performed genetic analyses of a multiethnic cohort of patients with idiosyncratic drug-induced liver injury (DILI) to identify variants associated with susceptibility. Methods We performed a genome-wide association study of 2048 individuals with DILI (cases) and 12,429 individuals without (controls). Our analysis included subjects of European (1806 cases and 10,397 controls), African American (133 cases and 1,314 controls), and Hispanic (109 cases and 718 controls) ancestry. We analyzed DNA from 113 Icelandic cases and 239,304 controls to validate our findings. Results We associated idiosyncratic DILI with rs2476601, a nonsynonymous polymorphism that encodes a substitution of tryptophan with arginine in the protein tyrosine phosphatase, non-receptor type 22 gene (PTPN22) (odds ratio [OR], 1.44; 95% CI, 1.28–1.62; P=1.2x10–9 and replicated the finding in the validation set (OR, 1.48; 95% CI, 1.09–1.99; P=.01). The minor allele frequency showed the same effect size (OR > 1) among ethnic groups. The strongest association was with amoxicillin and clavulanate-associated DILI in persons of European ancestry (OR, 1.62; 95% CI, 1.32–1.98; P=4.0x10–6; allele frequency=13.3%), but the polymorphism was associated with DILI of other causes (OR, 1.37; 95% CI, 1.21–1.56; P= 1.5x10–6; allele frequency=11.5%). Among amoxicillin- and clavulanate-associated cases of European ancestry, rs2476601 doubled the risk for DILI among those with the HLA risk alleles A*02:01 and DRB1*15:01. Conclusions In a genome-wide association study, we identified rs2476601 in PTPN22 as a non-HLA variant that associates with risk of liver injury caused by multiple drugs and validated our finding in a separate cohort. This variant has been associated with increased risk of autoimmune diseases, providing support for the concept that alterations in immune regulation contribute to idiosyncratic DILI.
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    Mutant and wild-type p53 form complexes with p73 upon phosphorylation by the kinase JNK
    (2018-04) Wolf, Eric R.; McAtarsney, Ciaran P.; Bredhold, Kristin E.; Kline, Amber M.; Mayo, Lindsey D.; Pediatrics, School of Medicine
    The transcription factors p53 and p73 are critical to the induction of apoptotic cell death, particularly in response to cell stress that activates c-Jun N-terminal kinase (JNK). Mutations in the DNA-binding domain of p53, which are commonly seen in cancers, result in conformational changes that enable p53 to interact with and inhibit p73, thereby suppressing apoptosis. In contrast, wild-type p53 reportedly does not interact with p73. We found that JNK-mediated phosphorylation of Thr81 in the proline-rich domain (PRD) of p53 enabled wild-type p53, as well as mutant p53, to form a complex with p73. Structural algorithms predicted that phosphorylation of Thr81 exposes the DNA-binding domain in p53 to enable its binding to p73. The dimerization of wild-type p53 with p73 facilitated the expression of apoptotic target genes [such as those encoding p53–up-regulated modulator of apoptosis (PUMA) and Bcl-2-associated X protein (BAX)] and, subsequently, the induction of apoptosis in response to JNK activation by cell stress in various cells. Thus, JNK phosphorylation of mutant and wild-type p53 promotes the formation of a p53/p73 complex that determines cell fate: apoptosis in the context of wild-type p53 or cell survival in the context of the mutant. These findings refine our current understanding of both the mechanistic links between p53 and p73 and the functional role for Thr81 phosphorylation.
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    Paroxysmal extreme pain disorder M1627K mutation in human Nav1.7 renders DRG neurons hyperexcitable
    (BioMed Central, 2008-09-19) Dib-Hajj, Sulayman D.; Estacion, Mark; Jarecki, Brian W.; Tyrrell, Lynda; Fischer, Tanya Z.; Lawden, Mark; Cummins, Theodore R.; Waxman, Stephen G.; Pharmacology and Toxicology, School of Medicine
    Background: Paroxysmal extreme pain disorder (PEPD) is an autosomal dominant painful neuropathy with many, but not all, cases linked to gain-of-function mutations in SCN9A which encodes voltage-gated sodium channel Nav1.7. Severe pain episodes and skin flushing start in infancy and are induced by perianal probing or bowl movement, and pain progresses to ocular and mandibular areas with age. Carbamazepine has been effective in relieving symptoms, while other drugs including other anti-epileptics are less effective. Results: Sequencing of SCN9A coding exons from an English patient, diagnosed with PEPD, has identified a methionine 1627 to lysine (M1627K) substitution in the linker joining segments S4 and S5 in domain IV. We confirm that M1627K depolarizes the voltage-dependence of fast-inactivation without substantially altering activation or slow-inactivation, and inactivates from the open state with slower kinetics. We show here that M1627K does not alter development of closed-state inactivation, and that M1627K channels recover from fast-inactivation faster than wild type channels, and produce larger currents in response to a slow ramp stimulus. Using current-clamp recordings, we also show that the M1627K mutant channel reduces the threshold for single action potentials in DRG neurons and increases the number of action potentials in response to graded stimuli. Conclusion: M1627K mutation was previously identified in a sporadic case of PEPD from France, and we now report it in an English family. We confirm the initial characterization of mutant M1627K effect on fast-inactivation of Nav1.7 and extend the analysis to other gating properties of the channel. We also show that M1627K mutant channels render DRG neurons hyperexcitable. Our new data provide a link between altered channel biophysics and pain in PEPD patients.
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    Rare coding variants and X-linked loci associated with age at menarche
    (Nature Publishing Group, 2015-08-04) Lunetta, Kathryn L.; Day, Felix R.; Sulem, Patrick; Ruth, Katherine S.; Tung, Joyce Y.; Hinds, David A.; Esko, Tõnu; Elks, Cathy E.; Altmaier, Elisabeth; He, Chunyan; Huffman, Jennifer E.; Mihailov, Evelin; Porcu, Eleonora; Robino, Antonietta; Rose, Lynda M.; Schick, Ursula M.; Stolk, Lisette; Teumer, Alexander; Thompson, Deborah J.; Traglia, Michela; Wang, Carol A.; Yerges-Armstrong, Laura M.; Antoniou, Antonis C.; Barbieri, Caterina; Coviello, Andrea D.; Cucca, Francesco; Demerath, Ellen W.; Dunning, Alison M.; Gandin, Ilaria; Grove, Megan L.; Gudbjartsson, Daniel F.; Hocking, Lynne J.; Hofman, Albert; Huang, Jinyan; Jackson, Rebecca D.; Karasik, David; Kriebel, Jennifer; Lange, Ethan M.; Lange, Leslie A.; Langenberg, Claudia; Li, Xin; Luan, Jian'an; Mägi, Reedik; Morrison, Alanna C.; Padmanabhan, Sandosh; Pirie, Ailith; Polasek, Ozren; Porteous, David; Reiner, Alex P.; Rivadeneira, Fernando; Rudan, Igor; Sala, Cinzia F.; Schlessinger, David; Scott, Robert A.; Stöckl, Doris; Visser, Jenny A.; Völker, Uwe; Vozzi, Diego; Wilson, James G.; Zygmunt, Marek; Boerwinkle, Eric; Buring, Julie E.; Crisponi, Laura; Easton, Douglas F.; Hayward, Caroline; Hu, Frank B.; Liu, Simin; Metspalu, Andres; Pennell, Craig E.; Ridker, Paul M.; Strauch, Konstantin; Streeten, Elizabeth A.; Toniolo, Daniela; Uitterlinden, André G.; Ulivi, Sheila; Völzke, Henry; Wareham, Nicholas J.; Wellons, Melissa; Franceschini, Nora; Chasman, Daniel I.; Thorsteinsdottir, Unnur; Murray, Anna; Stefansson, Kari; Murabito, Joanne M.; Ong, Ken K.; Perry, John R. B.; Department of Epidemiology, Richard M. Fairbanks School of Public Health
    More than 100 loci have been identified for age at menarche by genome-wide association studies; however, collectively these explain only ~3% of the trait variance. Here we test two overlooked sources of variation in 192,974 European ancestry women: low-frequency protein-coding variants and X-chromosome variants. Five missense/nonsense variants (in ALMS1/LAMB2/TNRC6A/TACR3/PRKAG1) are associated with age at menarche (minor allele frequencies 0.08–4.6%; effect sizes 0.08–1.25 years per allele; P<5 × 10−8). In addition, we identify common X-chromosome loci at IGSF1 (rs762080, P=9.4 × 10−13) and FAAH2 (rs5914101, P=4.9 × 10−10). Highlighted genes implicate cellular energy homeostasis, post-transcriptional gene silencing and fatty-acid amide signalling. A frequently reported mutation in TACR3 for idiopathic hypogonatrophic hypogonadism (p.W275X) is associated with 1.25-year-later menarche (P=2.8 × 10−11), illustrating the utility of population studies to estimate the penetrance of reportedly pathogenic mutations. Collectively, these novel variants explain ~0.5% variance, indicating that these overlooked sources of variation do not substantially explain the ‘missing heritability’ of this complex trait.
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    Role of RPL39 in Metaplastic Breast Cancer
    (Oxford, 2017) Dave, Bhuvanesh; Gonzalez, Daniel D.; Liu, Zhi-Bin; Li, Xiaoxian; Wong, Helen; Granados, Sergio; Ezzedine, Nadeer E.; Sieglaff, Douglas H.; Ensor, Joe E.; Miller, Kathy D.; Radovich, Milan; Eterovic, Agda Karina; Gross, Steven S.; Elemento, Olivier; Mills, Gordon B.; Gilcrease, Michael Z.; Chang, Jenny C.; Medicine, School of Medicine
    Background: Metaplastic breast cancer is one of the most therapeutically challenging forms of breast cancer because of its highly heterogeneous and chemoresistant nature. We have previously demonstrated that ribosomal protein L39 (RPL39) and its gain-of-function mutation A14V have oncogenic activity in triple-negative breast cancer and this activity may be mediated through inducible nitric oxide synthase (iNOS). The function of RPL39 and A14V in other breast cancer subtypes is currently unknown. The objective of this study was to determine the role and mechanism of action of RPL39 in metaplastic breast cancer. Methods: Both competitive allele-specific and droplet digital polymerase chain reaction were used to determine the RPL39 A14V mutation rate in metaplastic breast cancer patient samples. The impact of RPL39 and iNOS expression on patient overall survival was estimated using the Kaplan-Meier method. Co-immunoprecipitation and immunoblot analyses were used for mechanistic evaluation of RPL39. Results: The RPL39 A14V mutation rate was 97.5% (39/40 tumor samples). High RPL39 (hazard ratio = 0.71, 95% confidence interval = 0.55 to 0.91, P = .006) and iNOS expression (P = .003) were associated with reduced patient overall survival. iNOS inhibition with the pan-NOS inhibitor NG-methyl-L-arginine acetate decreased in vitro proliferation and migration, in vivo tumor growth in both BCM-4664 and BCM-3807 patient-derived xenograft models (P = .04 and P = .02, respectively), and in vitro and in vivo chemoresistance. Mechanistically, RPL39 mediated its cancer-promoting actions through iNOS signaling, which was driven by the RNA editing enzyme adenosine deaminase acting on RNA 1. Conclusion: NOS inhibitors and RNA editing modulators may offer novel treatment options for metaplastic breast cancer.
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    A system for detecting high impact-low frequency mutations in primary tumors and metastases
    (Springer Nature, 2018-01-11) Anjanappa, Manjushree; Hao, Yangyang; Simpson, Edward R; Bhat-Nakshatri, Poornima; Nelson, Jennifer B; Tersey, Sarah A; Mirmira, Raghavendra G; Cohen-Gadol, Aaron A; Saadatzadeh, M. Reza; Li, Lang; Fang, Fang; Nephew, Kenneth P.; Miller, Kathy D.; Liu, Yunlong; Nakshatri, Harikrishna; Medical and Molecular Genetics, School of Medicine
    Tumor complexity and intratumor heterogeneity contribute to subclonal diversity. Despite advances in next-generation sequencing (NGS) and bioinformatics, detecting rare mutations in primary tumors and metastases contributing to subclonal diversity is a challenge for precision genomics. Here, in order to identify rare mutations, we adapted a recently described epithelial reprograming assay for short-term propagation of epithelial cells from primary and metastatic tumors. Using this approach, we expanded minor clones and obtained epithelial cell-specific DNA/RNA for quantitative NGS analysis. Comparative Ampliseq Comprehensive Cancer Panel sequence analyses were performed on DNA from unprocessed breast tumor and tumor cells propagated from the same tumor. We identified previously uncharacterized mutations present only in the cultured tumor cells, a subset of which has been reported in brain metastatic but not primary breast tumors. In addition, whole-genome sequencing identified mutations enriched in liver metastases of various cancers, including Notch pathway mutations/chromosomal inversions in 5/5 liver metastases, irrespective of cancer types. Mutations/rearrangements in FHIT, involved in purine metabolism, were detected in 4/5 liver metastases, and the same four liver metastases shared mutations in 32 genes, including mutations of different HLA-DR family members affecting OX40 signaling pathway, which could impact the immune response to metastatic cells. Pathway analyses of all mutated genes in liver metastases showed aberrant tumor necrosis factor and transforming growth factor signaling in metastatic cells. Epigenetic regulators including KMT2C/MLL3 and ARID1B, which are mutated in >50% of hepatocellular carcinomas, were also mutated in liver metastases. Thus, irrespective of cancer types, organ-specific metastases may share common genomic aberrations. Since recent studies show independent evolution of primary tumors and metastases and in most cases mutation burden is higher in metastases than primary tumors, the method described here may allow early detection of subclonal somatic alterations associated with metastatic progression and potentially identify therapeutically actionable, metastasis-specific genomic aberrations.