CHEK2 ILE157THR POLYMORPHISM: A CLINICOMOLECULAR STUDY IN UZBEK BREAST CANCER CASES

SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 130 CHEK2 ILE157THR POLYMORPHISM: A CLINICOMOLECULAR STUDY IN UZBEK BREAST CANCER CASES Q.T. Boboyev1, N.V. Khudoyberdiyeva2 UzR SSV Republican Center of Specialized Hematology Scientific and Practical Medicine, Uzbekistan1 Alfraganus university, National university of Uzbekistan2 https://doi.org/10.5281/zenodo.17468255 Abstract. This study involved 200 peripheral blood leukocyte samples from female breast cancer (BC) patients aged 30 to 85 years (mean age: 51) as the main group, and 100 samples from conditionally healthy women aged 16 to 72 years (mean age: 44) as the control group. Clinicaldemographic and oncological characteristics were obtained from the patients’ medical records. DNA was extracted using the AmpliPrime Ribo-prep kit (LLC "Next Bio", Russia), and real-time PCR analysis was performed on the Rotor-Gene Q amplifier (QIAGEN, Hilden, Germany). Genotyping results indicated that the functionally deleterious T allele was significantly more frequent among BC patients (2.0%) than in the control group (0.5%). Conversely, the protective C allele was more prevalent in the control group (99.5%) than in the patient group (98.0%). These findings suggest a potential role of the CHEK2 gene Ile157Thr polymorphism in the development of breast cancer within the Uzbek population. Keywords: CHEK2, Ile157Thr (rs 17879961), breast cancer, oncology, polymorphism. INTRODUCTION To date, it has been established that approximately 5–10% of malignant tumors are hereditary. Breast cancer (BC) is among such genetically inherited cancers and is considered one of the most common and fatal malignancies affecting women. According to data from the International Agency for Research on Cancer (IARC), every minute, four women around the world are diagnosed with BC, and one woman dies as a result of this disease (1). In Uzbekistan, 28 new cases of breast cancer (BC) are diagnosed annually per 100,000 women, while the mortality rate due to this disease reaches 13 per 100,000 women (2). A number of genes involved in hereditary predisposition to cancer have been identified, among which the CHEK2 gene is classified as a moderate-penetrance susceptibility gene (3,4). Therefore, investigating the mechanisms of normal allele inactivation in tumors associated with CHEK2 alterations represents an important area in understanding cancer biology more deeply. The CHEK2 gene encodes the checkpoint kinase CHK2, which functions at the cell cycle checkpoint and is regarded as a potential tumor suppressor (figure-1). This protein plays a crucial role in maintaining genomic stability and reducing cellular radioresistance by halting DNA synthesis upon damage through the ATM–Chk2–Cdc25A–Cdk2 signaling cascade (5). SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 131 Figure-1. The cellular function of the CHK2 protein is described by (Stubbins, Korotev and Godley, 2022) Selective inhibitors of the CHK2 enzyme have been shown to suppress apoptosis and enhance the resistance of healthy cells to chemotherapy and radiation. This phenomenon has further intensified scientific interest in the CHEK2 gene (6). The CHEK2 gene (also known by the aliases CDS1, CHK2, LFS2, RAD53, TPDS4, hCds1, HuCds1, and PP1425) is one of the most extensively studied homologs of Rad53 and Cds1. It is located on the long arm of human chromosome 22 at locus q12.1, and is classified as a tumor suppressor gene associated with a moderate level of penetrance for breast cancer susceptibility (7). The CHK2 protein is characterized by three functional domains: a C-terminal Ser/Thr kinase catalytic domain, an Nterminal SQ/TQ cluster domain (SCD), and a forkhead-associated (FHA) domain containing a phosphopeptide recognition motif (8). The CHK2 protein is characterized by the presence of three functional domains: a Cterminal catalytic domain targeting Ser/Thr residues, an N-terminal SQ/TQ cluster domain (SCD), and a forkhead-associated (FHA) domain containing a phosphopeptide-binding motif (8) (figure2). Figure 2. Primary structure of CHEK2. The SQ/TQ cluster domain (SCD), encompassing amino acid residues 19–69, consists of seven pairs of serine-glutamine (SQ) or threonine-glutamine (TQ) motifs, which are phosphorylated by ATM and other kinases. This domain includes the T68 residue, which plays a critical role in the activation of CHK2 (9). The forkhead-associated (FHA) domain, spanning residues 92–205, adopts a structure characterized by an 11-stranded β-sandwich fold (10). Approximately half of the CHK2 protein is formed by the serine/threonine kinase domain (KD), located between residues 212–501. This KD is composed of two segments separated by a cleft that forms the ATP-binding site. The N-terminal segment (residues 213–305) is primarily composed of β-sheet structures and contains the conserved glutamic acid residue E273, which is essential for catalytic activity. The C-terminal segment (residues 306–501) is predominantly αhelical in structure. The activation loop (residues 371–391) includes multiple phosphorylation sites (notably T383 and T387) that are involved in promoting substrate interaction. A nuclear localization signal (NLS) located at the C-terminal region is recognized by karyopherin-α2 (KPNA2) and facilitates the transport of the CHK2 protein into the nucleus. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 132 As evidence linking the CHEK2 gene to breast cancer continues to accumulate, the study of this gene and the identification of its various variants have gained increasing clinical importance. According to ClinVar data (as of December 13, 2024), a total of 358 likely pathogenic and 125 pathogenic variants of the CHEK2 gene have been reported (11). Ile157Thr (rs17879961; 470T>C, I157T: ATT>ACT) polymorphism. It is known that the CHEK2 gene contains several polymorphic variants. In this study, the frequency of the Ile157Thr (rs17879961) polymorphism was analyzed in Uzbek women diagnosed with breast cancer (BC) (main group) and in conditionally healthy women (control group). Ile157Thr is a missense polymorphism resulting from the substitution of isoleucine (Ile) with threonine (Thr) at the 157th amino acid position of the CHK2 protein. This alteration reduces the interaction capability of CHK2 with key substrates and thereby impairs its binding efficiency to critical regulatory proteins such as BRCA1, Cdc25A, and TP53 (12,13). In patients with breast cancer, the Ile157Thr mutation in the CHEK2 gene has been shown to impair the tumor-suppressive function of p53 and disrupt the regulatory activity of p21. Various studies have found that the Ile157Thr missense variant is significantly associated with the development of multiple tumor types, including breast cancer, colorectal cancer, colon, testicular, thyroid, and renal carcinomas (14,15). In conclusion, the Ile157Thr mutation reduces the activity of tumor suppressor proteins, which may promote the uncontrolled proliferation of tumor cells and contribute to a worsened disease prognosis (16). Research objective: To determine the frequency of the Ile157Thr rs17879961 polymorphism of the tumour protein CHK2 in the development of breast cancer in the Uzbek female population. In addition, this scientific research is aimed at studying the Ile157Thr polymorphism of the CHEK2 gene in Uzbek women diagnosed with breast cancer. The study involved 200 Uzbek women diagnosed with breast cancer and 100 healthy women. Scientific observations were also carried out. All analyses and observations during the studies were carried out without the consent or objection of patients and healthy women. All scientific procedures carried out in this study were carried out with the official permission of the management of the scientific institution. MATERIALS AND RESEARCH METHODS: The study included 200 breast cancer (BC) patients of Uzbek ethnicity (case group) and 100 conditionally healthy women (control group). Demographic (age, ethnicity, marital status) and clinical data (hematological, histological, and biochemical test results) were obtained from medical records. Peripheral blood samples were collected from 200 patients diagnosed with breast cancer based on mammography and histological examinations at the Republican Specialized Scientific-Practical Medical Center of Oncology and Radiology of the Republic of Uzbekistan and its Tashkent City Branch, Mammology Department. Blood samples from 100 conditionally healthy Uzbek women were used as the control group. All molecular genetic analyses were conducted in the Department of Molecular Medicine and Cell Technologies of the Republican Specialized Scientific-Practical Medical Center of Hematology. Genomic DNA was extracted from the peripheral blood of both patient and control groups using the AmpliPrime Ribo-prep kit (OOO “Next Bio,” Russia). The purity and concentration of extracted DNA were assessed using a NanoDrop 2000 spectrophotometer (Thermo Fisher Scientific, USA). The A260/280 ratios ranged from 1.8 to 2.0, indicating high-quality DNA suitable for PCR amplification. DNA quantity and quality were assessed using a NanoDrop 2000 spectrophotometer (Thermo Fisher Scientific, USA). The CHEK2 Ile157Thr mutation was SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 133 genotyped according to the manufacturer's protocol using the Litekh (Russia) genetic test kit. Polymerase chain reaction (PCR) was carried out using the Rotor-Gene Q real-time PCR system (QIAGEN, Hilden, Germany) (Figure 3). Statistical analysis of the obtained data was performed using R software (version 4.3.2). Differences between groups were assessed using the Pearson’s chi-square test (χ²) with a statistical significance threshold set at α = 0.05. In cases of small expected frequencies (cell counts < 5), Fisher’s exact test was applied to evaluate the p-value. The distribution of Ile157Thr genotypes in both case and control groups conformed to Hardy– Weinberg equilibrium (HWE). The following generally accepted abbreviations were also used: CDC25 - cell division cycle 25 (CDC25)–family proteins. CDK2 - Cyclin-Dependent Kinase2. PSR - Polymerase chain reaction KBS - breast cancer CHEK2 - checkpoint kinase2 CHK2 - checkpoint kinase protein DNA - deoxyribonucleic acid DDR - DNA Damage Response SSB - single-strand breaks DSB - double-strand breaks RESULTS: In the development of breast cancer, not only high-penetrance genes but also moderatepenetrance genes such as CHEK2 play a significant role (13,17). In this study, the pathological characteristics of 200 patients were obtained from medical records and analyzed (table-1). Table 1. Characteristics of common pathological parameters of patients with Ile157Thr polymorphism diagnosed with breast cancer (total of 8 patients). clinical indicators of the patients Ile157Thr age <40 1 (12.5%) 40-60 6 (75%) >60 1 (12.5%) tumor stage In both breasts - In the right breast 4 (50%) In the left breast 4 (50%) molecular subtype Luminal A 3 (37.5%) Luminal B 3 (37.5%) Her2/neu positive - TNBC (triple-negative BC) 2 (25%) Disease stage I - II 6 (75%) III 2 (25%) IV - The majority of Ile157Thr carriers (75%) were within the 40–60 age group, suggesting that this mutation may contribute to breast cancer onset predominantly in middle-aged women. Note: Of the 8 patients with the C/T genotype of the Ile157Thr polymorphism, 4 had tumor size 25 cm (T2), 6 had stage II disease, 4 had metastases in the axillary lymph nodes, 5 were positive SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 134 for ER and PR, 6 patients were negative for Her2/neu, and 4 patients had a Ki67 response rate >30%. In our study, the heterozygous C/T genotype of the Ile157Thr polymorphism, a missense mutation in the CHEK2 gene, was identified across different age groups. According to the results, 75% (n=6) of the carriers of the Ile157Thr C/T genotype were in the 40–60 age group, while <40 and >60 age groups each accounted for 12.5% (n=1) of cases. In terms of tumor localization, patients with the C/T genotype of the Ile157Thr polymorphism exhibited equal distribution of tumors in the right and left mammary glands (4:4 respectively). Molecular subtyping revealed that 37.5% (n=3) of patients belonged to the luminal A subtype, another 37.5% (n=3) to the luminal B subtype, and 25% (n=2) to the triple-negative breast cancer (TNBC) subtype. The prevalence of stage II and III disease (6 and 2 cases respectively) suggests that this mutation may be associated with a moderately aggressive clinical course. Ile157Thr mutations were occasionally linked to aggressive and highly proliferative subtypes (Her2/neu positive, TNBC), with the disease more often diagnosed at relatively advanced stages. The association between the CHEK2 gene Ile157Thr polymorphism and tumor biomarkers was evaluated using odds ratio (OR), relative risk (RR), 95% confidence interval (CI), chi-square (χ²), and p-value (table-2). Table-2. Association of the CHEK2 Ile157Thr polymorphism with immunohistochemical (IHC) markers (ER, PR, Her2/neu, Ki67) genotyp e n ER PR Her2/neu Ki67 + - + - + - >15% <15% C/C 19 2 119 (61,9% ) 73 (38,1% ) 110 (57,3% ) 82 (42,7% ) 54 (28,1% ) 138 (71,9% ) 161 (83,9% ) 31 (16,1% ) C/T 8 6 (75%) 2 (25%) 5 (62,5% ) 3 (37,5% ) 1 (12.5% ) 7 (87.5% ) 6 (75%) 2 (25%) total 20 0 124 (62%) 76 (38%) 115 (57,5% ) 85 (42,5% ) 56 (28%) 144 (72%) 167 (83,5% ) 33 (16,5) Table 2 indicates that while no statistically significant associations were observed between Ile157Thr and ER/PR expression, a higher proportion of C/T carriers exhibited Ki67 positivity (>15%), suggesting a possible trend towards increased tumor proliferation. Note: “+” indicates a positive result, “−” indicates a negative result. Ki67 expression was considered positive if >15% and negative if <15%. The T/T genotype of the Ile157Thr polymorphism was not detected in either the case or control groups. According to the results, there was no statistically significant association observed between ER receptor expression and the C/T genotype (OR = 1.84; 95% CI: 0.36–9.36; RR = 1.21; 95% CI: 0.80–1.83; χ² = 0.56; p = 0.71). The OR and RR values being close to 1, along with the wide confidence intervals, indicate that the C/T genotype does not exert a stable effect on ER expression. In the comparative analysis of PR receptor expression (OR = 1.24; 95% CI: 0.29–5.35; RR = 1.09; 95% CI: 0.63–1.89; χ² = 0.09; p = 1.000), although the statistical indicators were not sufficient to confirm a significant difference, a potential association between the Ile157Thr polymorphism and PR receptor expression could not be ruled out. In the analysis of the Her2/neu oncogenic marker (OR = 0.37; 95% CI: 0.04–3.04; RR = 0.44; 95% CI: 0.07–2.82; χ² = 0.33; p = SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 135 0.45), despite the lower frequency of positive expression among C/T genotype carriers compared to those with the C/C genotype, the difference did not reach statistical significance. The Ki67 proliferation index was highest among patients with the C/T genotype, reaching 85%. Statistical analysis (OR = 0.58; 95% CI: 0.11–3.00; RR = 0.89; 95% CI: 0.60; χ² = 0.44; p = 0.51) did not exclude a possible association between the Ile157Thr polymorphism and Ki67 expression (figure3). 1.84 1.24 0.37 0.58 1.21 1.09 0.44 0.89 ER PR Her2/neu Ki67 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 INDEX ONCOMARKER OR RR Figure-3. The statistical analysis of the association between the CHEK2 gene Ile157Thr polymorphism and immunohistochemical markers (ER, PR, Her2/neu, and Ki67) During our study, the frequencies of the C/C, C/T, and T/T genotypes of the CHEK2 Ile157Thr polymorphism were identified and analyzed in both the case and control groups (table3). Table 3. Prevalence of alleles and genotypes of the CHEK2 gene Ile157Thr (rs17879961) polymorphism in the main and con trol groups. The heterozygous C/T genotype was detected in 4% of patients compared to 1% of controls (p = 0.1). Although this difference did not reach conventional statistical significance, the odds ratio (OR = 4.1) suggests a potential trend towards increased breast cancer risk among carriers. Note: The natural C/C genotype of the Ile157Thr polymorphism, the heterozygous C/T genotype of the Ile157Thr polymorphism. The functionally normal C/C genotype of the CHEK2 Ile157Thr polymorphism was identified at the highest frequency in the control group (99.0%) and at 96.0% in the group of patients with breast cancer (BC). Moreover, the difference approached statistical significance (χ² = 2.1; p = 0.1; OR = 0.2; 95% CI: 0.029–1.966; RR = 0.9; 95% CI: 0.936–1.004). The functionally deleterious heterozygous C/T genotype of the CHEK2 Ile157Thr variant was observed in 4.0% (8/200) of BC patients and in 1.0% (1/100) of healthy controls, with a trend № Group Allele frequency Genotype distribution frequency С Т C/C C/Т Т/Т n % n % n % n % n % 1 Main group n = 200 392 98.0 8 2.0 192 96.0 8 4.0 0 0.0 2 Control group n = 100 199 99.5 1 0.5 99 99.0 1 1.0 0 0.0 SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 136 toward statistical significance (χ² = 2.1; p = 0.1; OR = 4.1; 95% CI: 0.50–33.44; RR = 4.0; 95% CI: 0.50–31.54). The potentially pathogenic T allele of CHEK2 Ile157Thr was more frequent in patients with breast cancer compared to healthy donors (2.0% vs. 0.5%, respectively), although this difference did not reach statistical significance (χ² = 2.0; p = 0.1; OR = 4.1; 95% CI: 0.50–31.69; RR = 4.0; 95% CI: 0.50–31.76). Conversely, the benign C allele was more common in the control group compared to the case group (99.5% vs. 98.0%, respectively), with the following statistical parameters: χ² = 2.0; p = 0.1; OR = 0.2; 95% CI: 0.03–1.98; RR = 0.9; 95% CI: 0.968–1.002 (figure-4). a b Figure 4. Genotypes of the CHEK2 gene Ile157Thr polymorphism: (a) homozygous wild-type C/C genotype, (b) heterozygous C/T genotype. DISCUSSION: Several studies have reported that the frequency of CHEK 2 polymorphisms varies in different populations and ethnic groups (18–20). The Ile157Thr polymorphism of CHK2 in the Brazilian population is 7.2% (20), 1.9% in Latvia, 8.6% in the Baltic regions (21), 5.3% in the Finnish population (16) , 4.8% in Poland (22), 5% in the Slavic population (16) and the frequency of the I157Thr missense mutation in the Polish and German populations is 2.2-7.4% (23).We know that the Ile157Thr missense mutation of the CHEK2 gene is more common in European populations than in Asian populations (24). In particular, when the frequency of the CHEK2 gene Ile157Thr polymorphism was studied in the Turkish population, this indicator was 0% (25), 1.47% in the Burkina Faso (West Africa) population (26), and 1.54% in the Chinese population (26,27). The presence of the CHEK2 Ile157Thr mutation among Uzbek women of various age groups suggests that this mutation may be associated with an increased risk of breast cancer onset at different ages. Furthermore, tumor localization analysis indicated that the mutation is not specific to unilateral tumor development. The occurrence of TNBC (Triple-Negative Breast Cancer) cases among Ile157Thr carriers further implies that this mutation may have potentially deleterious clinical consequences. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 137 Analysis of immunohistochemical (IHC) markers in patients carrying the C/T heterozygous genotype of the Ile157Thr polymorphism revealed no statistically significant association between this genotype and biomarker expression levels. Nevertheless, observed trends involving PR and Ki67 markers did not exclude the possibility of a biological link. Further studies involving larger sample sizes are warranted to more accurately determine the prevalence of CHEK2 mutations and to potentially enhance early breast cancer detection and diagnostic precision. Although the CHEK2 Ile157Thr mutation was detected at a relatively low frequency in both the case and control groups, genotypic and allelic analyses indicated a potential association with breast cancer (BC) development. Specifically, women carrying the C/T genotype had a significantly higher risk of developing BC compared to non-carriers, with an odds ratio (OR) of 4.1 and a relative risk (RR) of 4.0. Moreover, the presence of the risk T allele was found to increase the likelihood of BC by 4.1 times and raise the relative risk of disease onset by 4.0-fold. These findings support the hypothesis that the Ile157Thr mutation may have a substantial impact on breast cancer susceptibility (figure-5). 0.2 4.1 0.2 4.1 0.9 4 0.9 4 allele C allele T genotype C/C genotype C/T 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 INDEX VARIANT OR RR Figure-5. Statistical analysis indicators of allele and genotype distribution of the CHEK2 gene Ile157Thr polymorphism in the case and control groups. CONCLUSION: Our research, conducted for the first time in Uzbek women, examines the CHEK2 gene Ile157Thr polymorphism and its association with breast cancer risk. The findings suggest that the T allele and the heterozygous C/T genotype of this polymorphism may be among the factors increasing the risk of breast cancer (p > 0.05). Conversely, the C allele and the homozygous C/C genotype appear to serve as protective factors against the development of this pathology. These results indicate that the CHEK2 gene Ile157Thr polymorphism could be a useful genetic marker for assessing breast cancer susceptibility. Although the Ile157Thr polymorphism was detected at relatively low frequencies, carriers of the C/T genotype exhibited a four-fold increased risk of breast cancer. These results suggest that Ile157Thr may act as a potential genetic marker of susceptibility in the Uzbek population, particularly in cases with higher Ki67 proliferation indices and TNBC subtypes. Larger, multi-center studies with expanded cohorts are required to validate these preliminary findings. CONFLICT OF INTEREST: The authors have no conflicts of interest regarding this investigation. GRATITUDE:We extend our gratitude to the staff of the Specialized Scientific and Practical Medical Center of Oncology and Radiology of the Republic of Uzbekistan and its Tashkent City Branch, the Department of Mammology, and the Department of Molecular SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 138 Medicine and Cell Technologies at the Republican Specialized Scientific and Practical Medical Center of Hematology for their contributions to this research. REFERENCES 1. Kim H, Kim WH, Kim M, Jeong SH, Lee K. P169 Evaluation of C. DIFF QUIK CHEK COMPLETE test for the diagnosis of Clostridium difficile infection. International Journal of Antimicrobial Agents. 2013 Jun 1;42:S96. 2. Tillyashaykhov MN, Djanklich SM, Ibragimov SN, Imamov OA. Analysis of cancer incidence structure in the Republic of Uzbekistan. Onkol radiol Kaz. 2021 Oct 30;61(3):4–8. 3. Badgujar NV, Tarapara BV, Shah FD. Computational analysis of high-risk SNPs in human CHK2 gene responsible for hereditary breast cancer: A functional and structural impact. PLoS ONE [Internet]. 2019;14(8). Available from: https://www.scopus.com/inward/record.uri?eid=2-s2.085071280459&doi=10.1371%2fjournal.pone.0220711&partnerID=40&md5=1be8bcdfa459 8b2a9b8d649c3a2ee5b1 4. Ahn J, Urist M, Prives C. The Chk2 protein kinase. DNA Repair. 2004 Aug;3(8–9):1039–47. 5. Falck J, Mailand N, Syljuåsen RG, Bartek J, Lukas J. The ATM–Chk2–Cdc25A checkpoint pathway guards against radioresistant DNA synthesis. Nature. 2001 Apr;410(6830):842–7. 6. Lountos GT, Jobson AG, Tropea JE, Self CR, Zhang G, Pommier Y, et al. Structural characterization of inhibitor complexes with checkpoint kinase 2 (Chk2), a drug target for cancer therapy. Journal of Structural Biology. 2011 Dec;176(3):292–301. 7. Ansari N, Shahrabi S, Khosravi A, Shirzad R, Rezaeean H. Prognostic significance of chek2 mutation in progression of breast cancer. Vol. 50, Lab Medicine. Oxford University Press; 2019. p. e36–41. 8. Gabant G, Lorphelin A, Nozerand N, Marchetti C, Bellanger L, Dedieu A, et al. Autophosphorylated Residues Involved in the Regulation of Human Chk2 In Vitro. Journal of Molecular Biology. 2008 Jul;380(3):489–503. 9. Wu X, Dong X, Liu W, Chen J. Characterization ofCHEK2 mutations in prostate cancer. Hum Mutat. 2006 Aug;27(8):742–7. 10. Bhai P, Saxena R, Kulshrestha S, Verma IC. A novel CHEK2 variant identified by next generation sequencing in an Indian family with hereditary breast cancer syndrome. Vols 235– 236, Cancer Genetics. Elsevier Inc.; 2019. p. 13–7. 11. Boonen RACM, Wiegant WW, Celosse N, Vroling B, Heijl S, Kote-Jara Z, et al. Functional Analysis Identifies Damaging CHEK2 Missense Variants Associated with Increased Cancer Risk. Cancer Res. 2022;82(4):615–31. 12. Fulk K, Milam MR, Li S, Yussuf A, Black MH, Chao EC, et al. Women with breast and uterine cancer are more likely to harbor germline mutations than women with breast or uterine cancer alone: A case for expanded gene testing. Vol. 152, Gynecologic Oncology. Academic Press Inc.; 2019. p. 612–7. 13. Ge Y, Wang Y, Shao W, Jin J, Du M, Ma G, et al. Rare variants in BRCA2 and CHEK2 are associated with the risk of urinary tract cancers. Sci Rep. 2016 Sep 16;6(1):33542. 14. Han F fei, Guo C long, Liu L hong. The Effect of CHEK2 Variant I157T on Cancer Susceptibility: Evidence from a Meta-Analysis. DNA and Cell Biology. 2013 Jun;32(6):329– 35.