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Tayebi N, Leon‐Ricardo B, McCall K, Mehinovic E, Engelstad K, Huynh V, Turner TN, Weisenberg J, Thio LL, Hruz P, Williams RSB, De Vivo DC, Petit V, Haller G, Gurnett CA. Quantitative determination of SLC2A1 variant functional effects in GLUT1 deficiency syndrome. Ann Clin Transl Neurol 2023; 10:787-801. [PMID: 37000947 PMCID: PMC10187726 DOI: 10.1002/acn3.51767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/08/2023] [Accepted: 03/12/2023] [Indexed: 04/03/2023] Open
Abstract
OBJECTIVE The goal of this study is to demonstrate the utility of a growth assay to quantify the functional impact of single nucleotide variants (SNVs) in SLC2A1, the gene responsible for Glut1DS. METHODS The functional impact of 40 SNVs in SLC2A1 was quantitatively determined in HAP1 cells in which SLC2A1 is required for growth. Donor libraries were introduced into the endogenous SLC2A1 gene in HAP1-Lig4KO cells using CRISPR/Cas9. Cell populations were harvested and sequenced to quantify the effect of variants on growth and generate a functional score. Quantitative functional scores were compared to 3-OMG uptake, SLC2A1 cell surface expression, CADD score, and clinical data, including CSF/blood glucose ratio. RESULTS Nonsense variants (N = 3) were reduced in cell culture over time resulting in negative scores (mean score: -1.15 ± 0.17), whereas synonymous variants (N = 10) were not depleted (mean score: 0.25 ± 0.12) (P < 2e-16). Missense variants (N = 27) yielded a range of functional scores including slightly negative scores, supporting a partial function and intermediate phenotype. Several variants with normal results on either cell surface expression (p.N34S and p.W65R) or 3-OMG uptake (p.W65R) had negative functional scores. There is a moderate but significant correlation between our functional scores and CADD scores. INTERPRETATION Cell growth is useful to quantitatively determine the functional effects of SLC2A1 variants. Nonsense variants were reliably distinguished from benign variants in this in vitro functional assay. For facilitating early diagnosis and therapeutic intervention, future work is needed to determine the functional effect of every possible variant in SLC2A1.
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Affiliation(s)
- Naeimeh Tayebi
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Brian Leon‐Ricardo
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Kevin McCall
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Elvisa Mehinovic
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
| | - Kristin Engelstad
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Vincent Huynh
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Tychele N. Turner
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
| | - Judy Weisenberg
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Liu L. Thio
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Paul Hruz
- Department of PediatricsWashington University in St LouisSt LouisMissouriUSA
| | - Robin S. B. Williams
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Darryl C. De Vivo
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | | | - Gabe Haller
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
- Department of Neurological SurgeryWashington University in St LouisSt LouisMissouriUSA
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Schiabor Barrett KM, Masnick M, Hatchell KE, Savatt JM, Banet N, Buchanan A, Willard HF. Clinical validation of genomic functional screen data: analysis of observed BRCA1 variants in an unselected population cohort. HGG ADVANCES 2022; 3:100086. [PMID: 35128484 PMCID: PMC8804171 DOI: 10.1016/j.xhgg.2022.100086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/06/2022] [Indexed: 12/02/2022] Open
Abstract
Functional assessment of genomic variants provides a promising approach to systematically examine the potential pathogenicity of variants independent of associated clinical data. However, making such conclusions requires validation with appropriate clinical findings. To this end, here, we use variant calls from exome data and BRCA1-related cancer diagnoses from electronic health records to demonstrate an association between published laboratory-based functional designations of BRCA1 variants and BRCA1-related cancer diagnoses in an unselected cohort of patient-participants. These findings validate and support further exploration of functional assay data to better understand the pathogenicity of rare variants. This information may be valuable in the context of healthy population genomic screening, where many rare, potentially pathogenic variants may not have sufficient associated clinical data to inform their interpretation directly.
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McAlarnen L, Stearns K, Uyar D. Challenges of Genomic Testing for Hereditary Breast and Ovarian Cancers. Appl Clin Genet 2021; 14:1-9. [PMID: 33488111 PMCID: PMC7814235 DOI: 10.2147/tacg.s245021] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/26/2020] [Indexed: 12/18/2022] Open
Abstract
Completion of genetic testing is increasingly important for the complex care of patients with suspected hereditary breast and ovarian cancers (HBOC) and their at-risk family members. Identification of individuals with pathogenic variants has implications for targeted treatment recommendations, risk reduction strategies, increased surveillance recommendations, as well as the genetic testing of family members, known as cascade testing or screening. Due to advances in technology and decreasing costs, what was once single-gene genetic testing has evolved into large-scale multi-gene panel genomic testing. As germline genomic testing for HBOC becomes more and more available, it is important to identify the challenges that are associated with its use. In this manuscript, we review the current issues faced by germline genomic testing for HBOC which include effectively managing the marked increases in genetic referrals, interpreting the vast amount of information yielded by newer testing methods such as next generation sequencing (NGS), recognizing the need for better cascade screening strategies, potential exacerbation of health disparities and improving support for patients navigating the emotional impact related to positive, negative and indeterminate testing results.
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Affiliation(s)
- Lindsey McAlarnen
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Kristen Stearns
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Denise Uyar
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI, USA
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Shaw T, Chan SH, Teo JX, Chong ST, Li ST, Courtney E, Ishak D, Sankar H, Ang ZLT, Chiang J, Loh M, Zhou L, Lee SC, Yeh HY, Kolinjivadi AM, Lim WK, Ngeow J. Investigation into the origins of an ancient BRCA1 founder mutation identified among Chinese families in Singapore. Int J Cancer 2020; 148:637-645. [PMID: 32745242 DOI: 10.1002/ijc.33241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/03/2020] [Accepted: 07/13/2020] [Indexed: 11/07/2022]
Abstract
Identification of ancestry-specific pathogenic variants is imperative for diagnostic, treatment, management and prevention strategies, and to understand penetrance/modifiers on risk. Our study aimed to determine the clinical significance of a recurrent BRCA1 c.442-22_442-13del variant of unknown significance identified among 13 carriers from six Chinese families, all with a significant history of breast and/or ovarian cancer. We further aimed to establish whether this was due to a founder effect and explore its origins. Haplotype analysis, using nine microsatellite markers encompassing 2.5 megabase pairs around the BRCA1 locus, identified a common haploblock specific to the variant carriers, confirming a founder effect. Variant age was estimated to date back 77.9 generations to 69 bc using the Gamma approach. On principal component analysis using single nucleotide polymorphisms merged with 1000 Genomes dataset, variant carriers were observed to overlap predominantly with the southern Han Chinese population. To determine pathogenicity of the variant, we assessed the functional effect on RAD51 foci formation as well as replication fork stability upon induction of DNA damage and observed an impaired DNA repair response associated with the variant. In summary, we identified an ancient Chinese founder mutation dating back 77.9 generations, possibly common among individuals of southern Han Chinese descent. Using evidence from phenotypic/family history studies, segregation analysis and functional characterization, the BRCA1 variant was reclassified from uncertain significance to pathogenic.
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Affiliation(s)
- Tarryn Shaw
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Sock Hoai Chan
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Jing Xian Teo
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore
| | - Siao Ting Chong
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Shao-Tzu Li
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Eliza Courtney
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Diana Ishak
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Haresh Sankar
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Zoe Li Ting Ang
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Jianbang Chiang
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - Marie Loh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Department of Epidemiology and Biostatistics, Imperial College London, London, UK
| | - Li Zhou
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Soo Chin Lee
- Department of Haematology-Oncology, National University Cancer Institute Singapore, Singapore
| | - Hui-Yuan Yeh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | | | - Weng Khong Lim
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore
| | - Joanne Ngeow
- Cancer Genetics Service, Division of Medical Oncology, National Cancer Centre Singapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
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Le Page C, Amuzu S, Rahimi K, Gotlieb W, Ragoussis J, Tonin PN. Lessons learned from understanding chemotherapy resistance in epithelial tubo-ovarian carcinoma from BRCA1and BRCA2mutation carriers. Semin Cancer Biol 2020; 77:110-126. [PMID: 32827632 DOI: 10.1016/j.semcancer.2020.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/20/2020] [Accepted: 08/12/2020] [Indexed: 02/07/2023]
Abstract
BRCA1 and BRCA2 are multi-functional proteins and key factors for maintaining genomic stability through their roles in DNA double strand break repair by homologous recombination, rescuing stalled or damaged DNA replication forks, and regulation of cell cycle DNA damage checkpoints. Impairment of any of these critical roles results in genomic instability, a phenotypic hallmark of many cancers including breast and epithelial ovarian carcinomas (EOC). Damaging, usually loss of function germline and somatic variants in BRCA1 and BRCA2, are important drivers of the development, progression, and management of high-grade serous tubo-ovarian carcinoma (HGSOC). However, mutations in these genes render patients particularly sensitive to platinum-based chemotherapy, and to the more innovative targeted therapies with poly-(ADP-ribose) polymerase inhibitors (PARPis) that are targeted to BRCA1/BRCA2 mutation carriers. Here, we reviewed the literature on the responsiveness of BRCA1/2-associated HGSOC to platinum-based chemotherapy and PARPis, and propose mechanisms underlying the frequent development of resistance to these therapeutic agents.
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Affiliation(s)
- Cécile Le Page
- McGill Research Institute of the McGill University Health Center, Montreal, QC, Canada.
| | - Setor Amuzu
- McGill Genome Centre, and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Kurosh Rahimi
- Department of Pathology du Centre hospitalier de l'Université de Montréal, Montreal, QC, Canada
| | - Walter Gotlieb
- Laboratory of Gynecologic Oncology, Lady Davis Research Institute, Jewish General Hospital, Montreal, QC, Canada
| | - Jiannis Ragoussis
- McGill Genome Centre, and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Patricia N Tonin
- Departments of Medicine and Human Genetics, McGill University, Cancer Research Program, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
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Consolidated BRCA1/2 Variant Interpretation by MH BRCA Correlates with Predicted PARP Inhibitor Efficacy Association by MH Guide. Int J Mol Sci 2020; 21:ijms21113895. [PMID: 32486089 PMCID: PMC7312854 DOI: 10.3390/ijms21113895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 12/26/2022] Open
Abstract
BRCA1/2 variants are prognostic biomarkers for hereditary breast and/or ovarian cancer (HBOC) syndrome and predictive biomarkers for PARP inhibition. In this study, we benchmarked the classification of BRCA1/2 variants from patients with HBOC-related cancer using MH BRCA, a novel computational technology that combines the ACMG guidelines with expert-curated variant annotations. Evaluation of BRCA1/2 variants (n = 1040) taken from four HBOC studies showed strong concordance within the pathogenic (98.1%) subset. Comparison of MH BRCA’s ACMG classification to ClinVar submitter content from ENIGMA, the international consortium of investigators on the clinical significance of BRCA1/2 variants, the ARUP laboratories, a clinical testing lab of the University of UTAH, and the German Cancer Consortium showed 99.98% concordance (4975 out of 4976 variants) in the pathogenic subset. In our patient cohort, refinement of patients with variants of unknown significance reduced the uncertainty of cancer-predisposing syndromes by 64.7% and identified three cases with potential family risk to HBOC due to a likely pathogenic variant BRCA1 p.V1653L (NM_007294.3:c.4957G > T; rs80357261). To assess whether classification results predict PARP inhibitor efficacy, contextualization with functional impact information on DNA repair activity were performed, using MH Guide. We found a strong correlation between treatment efficacy association and MH BRCA classifications. Importantly, low efficacy to PARP inhibition was predicted in 3.95% of pathogenic variants from four examined HBOC studies and our patient cohort, indicating the clinical relevance of the consolidated variant interpretation.
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