Association between BRCA1 rs799917 polymorphism and breast cancer risk: A meta-analysis of 19,878 subjects

Whole-exome Sequencing of Nigerian Prostate Tumors from the Prostate Cancer Transatlantic Consortium (CaPTC) Reveals DNA Repair Genes Associated with African Ancestry

In this study, we used whole-exome sequencing of a cohort of 45 advanced-stage, treatment-naïve Nigerian (NG) primary prostate cancer tumors and 11 unmatched nontumor tissues to compare genomic mutations with African American (AA) and European American (EA) The Cancer Genome Atlas (TCGA) prostate cancer. NG samples were collected from six sites in central and southwest Nigeria. After whole-exome sequencing, samples were processed using GATK best practices. BRCA1 (100%), BARD1 (45%), BRCA2 (27%), and PMS2(18%) had germline alterations in at least two NG nontumor samples. Across 111 germline variants, the AA cohort reflected a pattern [BRCA1 (68%), BARD1 (34%), BRCA2 (28%), and PMS2 (16%)] similar to NG samples. Of the most frequently mutated genes, BRCA1 showed a statistically (P ≤ 0.05) higher germline mutation frequency in men of African ancestry (MAA) and increasing variant frequency with increased African ancestry. Disaggregating gene-level mutation frequencies by variants revealed both ancestry-linked and NG-specific germline variant patterns. Driven by rs799917 (T>C), BRCA1 showed an increasing mutation frequency as African ancestry increased. BRCA2_rs11571831 was present only in MAA, and BRCA2_rs766173 was elevated in NG men. A total of 133 somatic variants were present in 26 prostate cancer-associated genes within the NG tumor cohort. BRCA2 (27%), APC (20%), ATM (20%), BRCA1 (13%), DNAJC6 (13%), EGFR (13%), MAD1L1 (13%), MLH1 (11%), and PMS2 (11%) showed mutation frequencies >10%. Compared with TCGA cohorts, NG tumors showed statistically significant elevated frequencies of BRCA2, APC, and BRCA1. The NG cohort variant pattern shared similarities (cosign similarities ≥0.734) with Catalogue of Somatic Mutations in Cancer signatures 5 and 6, and mutated genes showed significant (q < 0.001) gene ontology (GO) and functional enrichment in mismatch repair and non-homologous repair deficiency pathways. Here, we showed that mutations in DNA damage response genes were higher in NG prostate cancer samples and that a portion of those mutations correlate with African ancestry. Moreover, we identified variants of unknown significance that may contribute to population-specific routes of tumorigenesis and treatment. These results present the most comprehensive characterization of the NG prostate cancer exome to date and highlight the need to increase diversity of study populations.

Significance

MAA have higher rates of prostate cancer incidence and mortality, however, are severely underrepresented in genomic studies. This is the first study utilizing whole-exome sequencing in NG men to identify West African ancestry-linked variant patterns that impact DNA damage repair pathways.

Endometrial Cancer, BRCA1, and BRCA2 in the UK Biobank Cohort

OBJECTIVES

Endometrial cancer (EC) risk in BRCA1/2 mutation carriers has been uncertain. EC risk in women with germline BRCA1 or BRCA2 mutations was recently assessed in a multicenter cohort study. BRCA1/2 mutation carriers had a 2- to 3-fold increased risk for EC, with highest risk observed for the rare subgroups of serous-like and p53-abnormal EC in BRCA1 mutation carriers. To further evaluate risk, we looked at EC and BRCA1/2 in the UK Biobank cohort.

METHODS

EC diagnosis was ascertained using the 10th Revision of the International Classification of Diseases. We analyzed the single nucleotide polymorphisms (SNPs) rs799917 (BRCA1) and rs144848 (BRCA2). A case-control study found a possible association of rs799917 but not rs144848 with EC. Data processing was performed on Minerva, a Linux mainframe with Centos 7.6, at the Icahn School of Medicine at Mount Sinai.

RESULTS

Percentage ECs within genotypes for SNPs rs799917 and rs144848 was 0.6%. The variability within SNP genotypes was insignificant (P=0.288 for rs799917, 2-tailed Fisher exact test; P=0.931 for rs144848). In comparison, an estimated 70,200 women who had been diagnosed with uterine cancer between 1991 and 2010 were alive in the UK at the end of 2010. A total of 21,892,000 UK residents were ages 50 to 92; approximately half were women. Therefore, prevalence of EC in these UK women was 0.6%, identical to percentage EC within 6 genotypes for SNPs rs799917 and rs144848.

CONCLUSION

Although we cannot rule out an increase in several rare types of EC, our analysis suggests that the overall incidence or risk of EC does not appear to be increased by the presence of BRCA1 or BRCA2 mutations.

Single nucleotide polymorphisms in breast cancer susceptibility gene 1 are associated with susceptibility to lung cancer

BRCA1 is a tumor suppressor that has been found to be involved DNA synthesis during cell replication. In a recent study, the single nucleotide polymorphism (SNP), rs799917, in BRCA1 was found to be associated with the development and progression of various types of tumor. In the present study, the association between rs799917 and susceptibility to lung cancer was evaluated in a Han Chinese population in the Liaoning Province of China. The BRCA1 rs799917 genotypes (C/C, C/T and T/T) were analyzed using TaqMan quantitative PCR in 682 patients with lung cancer and 694 healthy controls, and the results were analyzed using a Student's t-test, a χ² test and logistic regression analysis. Individuals carrying the C/T or T/T genotype had a lower risk of lung cancer compared with those carrying the C/C genotype [odds ratio (OR), 0.741; P=0.021; and OR, 0.610; P=0.011, respectively). The C/T + T/T genotype group had an even lower risk (OR, 0.709; P=0.005) compared with that in the C/C genotype group. In the stratified analyses of non-smokers, individuals with the C/T or T/T genotype had a lower risk of developing lung cancer compared with that in those carrying the C/C genotype (OR, 0.681; P=0.013; and OR, 0.569; P=0.021, respectively). The stratified analyses of the BRCA1 rs799917 polymorphism based on pathological type, chemotherapy and radiotherapy, showed that in the squamous cell carcinoma, non-chemotherapy and non-radiotherapy subgroups, individuals with the T/T genotype had a lower risk of lung cancer compared with that in those carrying the C/C genotype (OR, 0.454; P=0.007; OR, 0.485; P=0.002; and OR, 0.599; P=0.020, respectively). In conclusion, the T allele of the rs799917 SNP in BRCA1 was associated with a lower risk of lung cancer in the ethnic Han Chinese population in Liaoning Province and may represent a protective factor against lung cancer.

Screening of BRCA1 variants c.190T>C, 1307delT, g.5331G>A and c.2612C>T in breast cancer patients from North India

The polymorphic variants of BRCA1, which lead to amino acid substitutions, have a known pathogenic role in breast cancer. The present study investigated in North Indian breast cancer patients the association of risk with four reported pathogenic variants of BRCA1: c.190T>C (p.Cys64Arg), 1307delT, g.5331G>A (p.G1738R) and c.2612C>T (p.Pro871Leu). Genotyping was done by PCR-RFLP method in 255 clinically confirmed breast cancer patients and 255 age and gender matched healthy individuals. For c.190T>C, 1307delT and g.5331G>A, all the patients and controls had the wild-type genotype indicating no association with breast cancer risk. For c.2612C>T polymorphism, the frequency of the CC, CT, and TT genotypes was 14.5 vs 15.7%, 59.6 vs 53.7% and 25.9 vs 30.6% in breast cancer patients and controls respectively. The frequency of heterozygotes (CT genotype) was higher in cases than controls but the difference was not statistically significant. Genetic model analysis showed no association of the four analyzed BRCA1 variants with breast cancer risk with any model. The studied variants were not associated with the risk of breast cancer in Punjab, North west India, suggesting a need for further screening of other BRCA1 variants. It is the first reported study on these 4 variants from India.

Novel Associations between BRCA1 Variants C.181 T>G (Rs28897672) and Ovarian Crisk in Saudi Females

BACKGROUND

Mutations in BRCA1 gene have been implicated in ovarian cancers, and BRCA testing may be conducted in high-risk women. This study was designed to determine the frequency of three single nucleotide polymorphisms (SNPs) variants in BRCA1 gene and BRCA1 expression in Saudi females with ovarian cancer.

METHODS

Expression levels of mRNA of BRCA1 gene were studied in 10 ovarian cancer and 10 normal ovarian tissues, by quantitative real time polymerase chain reaction (qPCR). The study also included 28 females who had suffered from ovarian cancer and had been successfully operated upon and 90 healthy females with no history of cancer. Blood was drawn in EDTA tubes and used for extraction of DNA. The genotyping was carried out using Taqman® SNP Genotyping kit by RT-PCR. The variants investigated included c.871 T>C (rs799917), c.1040 G>A (rs4986852), c.181 T>G (rs28897672) in BRCA1 gene.

RESULTS

The c.181 T>G (rs28897672) showed significantly different genotype and allele frequencies between the patients and the control subjects (p value = 0.002 and 0.02, respectively). The genotype TG was significantly protective (OR = 0.36, p value = 0.024). The mRNA expression of BRCA1 gene was found to be low in the ovarian cancer tissues.

CONCLUSIONS

This study showed that c.181 T>G in BRCA1 genes is associated with the development of ovarian cancer in Saudis. More studies are needed to unveil other SNPs that may be associated with ovarian cancer and to understand the mechanism(s) involved in reducing the expression of BRCA1 gene in ovarian cancer tissues.

Genetic Variants Associated with Clinicopathological Profiles in Sporadic Breast Cancer in Sri Lankan Women

PURPOSE

Several single nucleotide polymorphisms (SNPs) have been reported to be associated with clinicopathological profiles in sporadic breast cancer based on studies conducted on major population groups. The knowledge of the effects of these common genetic variants in South Asian populations remains limited. The present study aimed to investigate the association between a selected set of SNPs and the clinicopathological profiles in sporadic breast cancer in Sri Lankan women.

METHODS

A total of 350 postmenopausal women with histologically confirmed invasive breast cancer were genotyped for 58 SNPs located in 36 breast cancer related genes. The clinicopathological factors that were investigated included age of onset, tumor histologic grade, and lymph node involvement, as well as estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) status. Association testing was performed using logistic regression models adjusted for confounding factors.

RESULTS

Seven SNPs showed significant associations with clinicopathological profiles in breast cancer. The G allele of BRCA1:rs799917 (p=0.047; β [standard error; SE]=-1.069 [0.537]) and the G allele of NQO2:rs17136117 (p=0.040, β [SE]=1.901 [0.923]) were found to be associated with age of onset between 50 and 59 years. The C allele of CDH1:rs13689 (odds ratio [OR], 2.121; p=0.033) was found to be associated with ER-positive breast cancer. The A allele of AKT1:rs1130214 (OR, 2.095; p=0.011) and the C allele of NQO2:rs2071002 (OR, 1.632; p=0.045) were associated with HER2-positive breast cancer. The C allele of BRCA2:rs15869 (OR, 1.600; p=0.041) and the C allele of CCND1:rs7177 (OR, 1.555; p=0.041) were associated with high tumor histologic grade.

CONCLUSION

The common genetic variants identified in the AKT1, BRCA1, BRCA2, CCND1, CDH1, and NQO2 genes could serve as potential clinical and prognostic biomarkers in sporadic breast cancer patients. Further studies are required to validate our current findings in other populations.

The association between BRCA1 gene polymorphism and cancer risk: a meta-analysis

Many studies have reported that BRCA1 polymorphisms are associated with cancer risk, but the results remain controversial. The purpose of this meta-analysis is to evaluate the relationship between BRCA1 polymorphisms (rs799917, rs1799950, rs1799966, or rs16941) and cancer risk. Relevant studies were identified via a systematic search of the PubMed, Embase, and Web of Science databases up to July 31, 2017. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to examine the strength of the associations. Thirty-five studies published in 19 publications involving 28,094 cases and 50,657 controls were included in this meta-analysis. There was no obvious association between rs799917, rs1799966, or rs16941 polymorphisms and overall cancer risk in any genetic models. However, subgroup analyses revealed that the rs799917 polymorphism could decrease the risk of cervical cancer, esophageal squamous cell carcinoma (ESCC), gastric cancer, and non-Hodgkin lymphoma (NHL) among Asian populations in one or more genetic models and that rs16941 could increase overall cancer risk among Caucasian populations in the homozygote and recessive models. Our meta-analysis also indicated that rs1799950 could decrease the breast cancer (BC) risk among Caucasian populations in the homozygote and recessive models. In summary, our results suggest that BRCA1 polymorphisms may play an important role in the etiology of cancer. However, due to the limited number of studies, these findings should be confirmed by new studies with larger sample sizes that address various types of cancer.

Association between BRCA1 P871L polymorphism and cancer risk: evidence from a meta-analysis

Breast cancer 1 (BRCA1) gene makes great contributions to the repair of DNA. The association between BRCA1 P871L polymorphism and cancer risk has been investigated in a growing number of studies, but the conclusions are not conclusive. To obtain a comprehensive conclusion, we performed a meta-analysis of 24 studies with 13762 cases and 22388 controls. The pooled results indicated that BRCA1 gene P871L variant decreased risk of overall cancer (homozygous model: odds ratio (OR) = 0.89, 95%confidence interval (CI) = 0.79-1.00; recessive model: OR = 0.89, 95% CI = 0.80-0.99). The stratified analysis observed decreased risk associated with BRCA1 P871L in subgroups among Asians and high score studies, but not Caucasians or low score studies. In conclusion, despite several limitations, this meta-analysis suggested that BRCA1 P871L genetic variation may be associated with decreased susceptibility to cancer.

New variants in the BRCA1 gene in Buryat Mongol breast cancer patients: Report from two families

BACKGROUND

The BRCA1 mutations that are endemic to the Slavic population of Russia have not been identified among indigenous peoples, including the Buryats, Tuvinians and Altaians with hereditary breast cancer.

OBJECTIVE

This study was aimed to identify the mutations that are responsible for the occurrence of hereditary breast cancer in the indigenous population of the Republic of Buryatia.

METHODS

Mutations in the BRCA1 gene were identified in blood samples by Sanger-based sequencing.

RESULTS

We identified 11 polymorphisms (10 SNPs and 1 Indel) and 6 new unclassified sequence variants in the BRCA1 gene. In our study three new sequence variants (c.321T>A, c.366T>A, c.4357+2T>A) were found in position of previously described polymorphisms in dbSNPs: rs80357544 (c.321delT), rs190900046 (c.366T>G), and rs80358152 (c.4357+2T>C), respectively. Other three new sequence variants (c.3605A>G, c.1998A>C, and c.80+13A>C) have not been previously described in dbSNP, BIC and Human Gene Mutation Databases.

CONCLUSIONS

We described six new sequence variants that have never been published in the literature or databases. Further studies are required to confirm the impact of new sequence variants on the risk of breast cancer in the Buryat Mongol population.