Prevalence of RECQL germline variants in Pakistani early-onset and familial breast cancer patients

Understanding genetic variations associated with familial breast cancer

BACKGROUND

Breast cancer is the most frequent cancer among women. Genetics are the main risk factor for breast cancer. Statistics show that 15-25% of breast cancers are inherited among those with cancer-prone relatives. BRCA1, BRCA2, TP53, CDH1, PTEN, and STK11 are the most frequent genes for familial breast cancer, which occurs 80% of the time. In rare situations, moderate-penetrance gene mutations such CHEK2, BRIP1, ATM, and PALB2 contribute 2-3%.

METHODS

A search of the PubMed database was carried out spanning from 2005 to July 2024, yielding a total of 768 articles that delve into the realm of familial breast cancer, concerning genes and genetic syndromes. After exclusion 150 articles were included in the final review.

RESULTS

We report on a set of 20 familial breast cancer -associated genes into high, moderate, and low penetrance levels. Additionally, 10 genetic disorders were found to be linked with familial breast cancer.

CONCLUSION

Familial breast cancer has been linked to several genetic diseases and mutations, according to studies. Screening for genetic disorders is recommended by National Comprehensive Cancer Network recommendations. Evaluation of breast cancer candidate variations and risk loci may improve individual risk assessment. Only high- and moderate-risk gene variations have clinical guidelines, whereas low-risk gene variants require additional investigation. With increasing use of NGS technology, more linkage with rare genes is being discovered.

Marginal Contribution of Pathogenic RAD51D Germline Variants to Pakistani Early-Onset and Familial Breast/Ovarian Cancer Patients

Introduction

RAD51D has been reported as a breast cancer (BC) and ovarian cancer (OC) predisposition gene, particularly among Caucasian populations. We studied the prevalence of RAD51D variants in Pakistani BC/OC patients.

Materials and Methods

In total, 371 young or familial BC/OC patients were thoroughly analyzed for RAD51D sequence variants using denaturing high-performance liquid chromatography pursued by DNA sequencing of differentially eluted amplicons. We also assessed the pathogenic effects of novel variants using in-silico algorithms. All detected RAD51D variants were investigated in 400 unaffected controls.

Results

No pathogenic RAD51D variant was detected. However, we identified nine unique heterozygous variants. Of these, two missense variants (p.Pro10Leu and p.Ile311Asn) and one intronic variant (c.481-26_23delGTTC) were classified as in silico-predicted variants of uncertain significance, with a frequency of 0.8% (3/371). The p.Pro10Leu variant was detected in a 28-year-old female BC patient of Punjabi ethnic background, whose mother and maternal cousin had BCs at ages 53 and 40, respectively. This variant was also detected in 1/400 (0.25%) healthy controls, where the control subject's daughter had acute lymphoblastic leukemia. The p.Ile311Asn variant was identified in a female BC patient at age 29 of Punjabi ethnicity and in 1/400 (0.25%) healthy controls, where the control subject's daughter had Hodgkin's disease at age 14. A novel intronic variant, c.481-26_-23delGTTC, was found in a 30-year-old Punjabi female BC patient but not in 400 healthy controls.

Conclusion

No pathogenic RAD51D variant was identified in the current study. Our study data suggested a negligible association of RAD51D variants with BC/OC risk in Pakistani women.

Contribution of constitutional BRCA1 promoter methylation to early-onset and familial breast cancer patients from Pakistan

PURPOSE

Constitutional BRCA1 promoter methylation has been identified as a potential risk factor for breast cancer (BC) in the Caucasian population. However, this data is lacking for BC patients of Asian origin. Therefore, we assessed the contribution of constitutional BRCA1 promoter methylation in Pakistani BC patients.

METHODS

A total of 385 BRCA1/2-negative index BC patients (197 early-onset BC (≤ 30 years), 152 familial BC, 17 familial BC and ovarian cancer, 19 male BC) and 107 healthy controls were screened for the constitutional BRCA1 promoter methylation by methylation-sensitive high-resolution melting assay. Overall, 131 patients displayed triple-negative BC (TNBC) and 254 non-TNBC phenotypes. The prevalence of BRCA1 promoter methylation was calculated based on clinicopathological characteristics using univariable and multivariable logistic regression models.

RESULTS

Constitutional BRCA1 promoter methylation was identified in 19.5% (75/385) of BC patients and 13.1% (14/107) of controls. The frequency of methylation was higher in early-onset BC (23.4% vs. 13.1%, P = 0.035) and TNBC patients (29.0% vs. 13.1%, P = 0.004) compared to controls. Methylation was also more prevalent in patients with high-grade than low-grade tumors (21.7% vs. 12.2%, P = 0.034) and progesterone receptor (PR)-negative than PR-positive tumors (26.0% vs. 13.9%, P = 0.004). Constitutional BRCA1 promoter methylation remained independently associated with TNBC phenotype (odds ratio 1.99; 95% CI 1.12-3.54; P = 0.02) after adjusting for BC diagnosis age, tumor grade, ER, and PR status.

CONCLUSION

Constitutional BRCA1 promoter methylation is associated with TNBC and can serve as a non-invasive blood-based biomarker for Pakistani TNBC patients.

Prevalence of FANCM germline variants in BRCA1/2 negative breast and/or ovarian cancer patients from Pakistan

The Fanconi anemia complementation group M (FANCM) gene is a potential candidate for breast/ovarian cancer susceptibility in European populations. Here, we examined the contribution of FANCM germline variants to hereditary breast and/or ovarian cancer in Pakistan. Comprehensive FANCM variant screening was performed in 201 BRCA1 and BRCA2 (BRCA1/2) negative Pakistani patients with and without triple-negative breast cancer (TNBC) and/or ovarian cancer, using denaturing high-performance liquid chromatography analysis (DHPLC) followed by DNA sequencing. Novel variants were tested for their potential effect on protein function using in silico tools. Reverse transcription (RT)-PCR analysis of RNA extracted from one deletion/insertion (delins) variant (p.K1780delinsNGIT) carrier and three non-carriers was performed to evaluate the impact of this variant on splicing. Furthermore, potentially functional variants were evaluated in 200 healthy female controls. A missense variant (p.V1857M) was identified in a 50-year-old TNBC patient with a family history of breast cancer. It was also identified in the index patient´s daughter, who was diagnosed with osteosarcoma at 15 years of age. Further, one delins variant (p.K1780delinsNGIT) was identified in a 45-year-old non-TNBC patient, but not detected in her brother, who was diagnosed with Hodgkin's lymphoma at 38 years of age. Based on in silico and RNA analyses, p.V1857M and p.K1780delinsNGIT were predicted as variants of uncertain significance (VUS), respectively. Both variants were absent in 200 healthy controls. Our findings suggest a marginal contribution of FANCM variants to hereditary breast/ovarian cancer in Pakistan, which need to be confirmed in larger studies.

Contribution of germline PALB2 variants to an unselected and prospectively registered pancreatic cancer patient cohort in Pakistan

BACKGROUND

Partner and localizer of BRCA2 (PALB2) is a pancreatic cancer (PC) susceptibility gene reported in Caucasians. However, limited data are available among Asians. We investigated the contribution of PALB2 germline variants to Pakistani PC patients.

METHODS

150 unselected and prospectively enrolled PC patients were comprehensively screened for PALB2 variants, using denaturing high-performance liquid chromatography and DNA sequencing. Novel variants were investigated for their pathogenic effect using in-silico tools. Potentially functional variants were screened in 200 controls.

RESULTS

Twenty-two different PALB2 variants were identified. A missense variant (p.Arg37His) was identified in a 48-years-old male patient with a family history of breast cancer. Another missense variant (p.Trp898Arg) was identified in a 48-years-old male patient with a family history of esophageal cancer. A novel 3' downstream variant (c.∗480A>G) was detected in a 34-years-old female patient with family history of lung cancer. Another novel 3' downstream variant (c.∗417A>C) was identified in a 41-years-old male patient. All these variants were absent in 200 controls. p.Arg37His and p.Trp898Arg were predicted as likely pathogenic. c.∗417A>C and c.∗480A>G were classified as variants of uncertain significance.

CONCLUSION

This is the first study that suggests a minimal contribution of PALB2 variants to PC risk in Pakistani population.

Spectrum of germline pathogenic variants using a targeted next generation sequencing panel and genotype-phenotype correlations in patients with suspected hereditary breast cancer at an academic medical centre in Pakistan

BACKGROUND

Breast cancer is the most common malignancy in women, affecting over 1.5 million women every year, which accounts for the highest number of cancer-related deaths in women globally. Hereditary breast cancer (HBC), an important subset of breast cancer, accounts for 5-10% of total cases. However, in Low Middle-Income Countries (LMICs), the population-specific risk of HBC in different ethnicities and the correlation with certain clinical characteristics remain unexplored.

METHODS

Retrospective chart review of patients who visited the HBC clinic and proceeded with multi-gene panel testing from May 2017 to April 2020. Descriptive and inferential statistics were used to analyze clinical characteristics of patients. Fisher's exact, Pearson's chi-squared tests and Logistic regression analysis were used for categorical variables and Wilcoxon rank-sum test were used for quantitative variables. For comparison between two independent groups, Mann-Whitney test was performed. Results were considered significant at a p value of < 0.05.

RESULTS

Out of 273 patients, 22% tested positive, 37% had a VUS and 41% had a negative genetic test result. Fifty-five percent of the positive patients had pathogenic variants in either BRCA1 or BRCA2, while the remaining positive results were attributed to other genes. Patients with a positive result had a younger age at diagnosis compared to those having a VUS and a negative result; median age 37.5 years, IQR (Interquartile range) (31.5-48). Additionally, patients with triple negative breast cancer (TNBC) were almost 3 times more likely to have a positive result (OR = 2.79, CI = 1.42-5.48 p = 0.003). Of all patients with positive results, 25% of patients had a negative family history of breast and/or related cancers.

CONCLUSIONS

In our HBC clinic, we observed that our rate of positive results is comparable, yet at the higher end of the range which is reported in other populations. The importance of expanded, multi-gene panel testing is highlighted by the fact that almost half of the patients had pathogenic or likely pathogenic variants in genes other than BRCA1/2, and that our test positivity rate would have only been 12.8% if only BRCA1/2 testing was done. As the database expands and protocol-driven referrals are made across the country, our insight about the genetic architecture of HBC in our population will continue to increase.

High Expression of RECQL Protein in ER-Positive Breast Tumours Is Associated With a Better Survival

Background

RECQL (also known as RECQ1 and RECQL1) is a gene of recent interest in breast cancer and an association between high levels of RECQL protein in breast cancer tumour cells and good survival of patients has been reported.

Methods

To validate this association, we measured the RECQL protein levels in tumours of 933 breast cancer patients using immunohistochemistry analysis and followed the patients for death from breast cancer.

Results

Women with a level of RECQL protein above the 75th percentile had better 15-year disease-specific survival among ER-positive patients (62.5% vs. 48.7%, HR= 0.72, 95%CI= 0.52-0.98, p-value = 0.04), but not among ER- patients (48.9% vs. 48.0%, HR= 1.07, 95%CI= 0.67-1.69, p-value= 0.79). Among the ER-negative patients, high RECQL protein levels were associated with better survival among women who received tamoxifen treatment (67.0% vs. 51.5%, HR= 0.64, 95%CI= 0.41-0.99, p-value= 0.04).

Conclusion

RECQL might be a new predictive marker for tamoxifen treatment among ER-positive patients.