Breast cancer remains the most common cancer among females around the globe and is associated with a major public health problem [1]. 

Although numerous environmental and lifestyle risk factors influence the development of the disease, susceptibility is considered primarily genetic in determining an individual's risk of this malignancy [2]. Among such determinants is the vitamin D receptor (VDR) gene. This particular gene has drawn special attention, primarily because the receptor plays an essential role in the mediation of vitamin D biological effects [3]. Vitamin D, in its active form (1,25-dihydroxyvitamin D), has anti-carcinogenic effects by binding to the VDR, a nuclear receptor that regulates the transcription of genes involved in cell proliferation, differentiation, apoptosis, and immune modulation [4]. Polymorphisms in the VDR gene can influence its activity, altering the downstream effects of vitamin D and potentially modulating cancer risk [5]. Several SNPs within the VDR gene have been studied quite elaborately with associations to multiple types of cancer, including breast cancer, which have been documented such as the FokI, BsmI, ApaI, and TaqI polymorphisms [6]. There are no sufficient explanations of mechanisms whereby VDR polymorphisms are associated with increased risk in breast cancer cases [7]. Variants, such as FokI, affect both the length of the VDR protein and its potential functional activity while intronic, or synonymous change like BsmI, ApaI and TaqI can influence expressions and mRNA stabilization [8]. These forms may interact, consequently, to confound still other genetic, as well as possibly environmental factors which are vitamin D level, hormonal status or ethnicity [9]. Despite the accumulation of evidence, studies investigating the association between VDR polymorphisms and breast cancer risk have yielded inconsistent findings [10]. This may be due to differences in study design, sample size, and population characteristics [11]. This underscores the need for well-designed studies to clarify these relationships and the potential of VDR polymorphisms as a biomarker for assessing breast cancer risk [12].

This study will evaluate the association of common VDR polymorphisms with breast cancer risk in a case-control cohort. The study will examine the distribution of genotypes and their association with risk factors to shed light on the genetic underpinnings of breast cancer and its implications for prevention and personalized medicine.

This was a case-control study that was conducted in a tertiary care hospital with 150 patients, who covered a two year span, and were divided into 75 cases of breast cancer and another 75, age-matched healthy controls. Institutional review board ethical approval and informed consent was obtained from all participants before their enrolment. The study included women between 25 to 65 years of age who had confirmed breast cancer cases based on histopathology, whereas the controls included healthy women with no history of malignancy. Participants with autoimmune diseases, chronic metabolic disorders, or on high-dose vitamin D supplementation were excluded in the study to minimize confounding factors.

Samples were collected from each participant's peripheral blood, from which genomic DNA was obtained using the phenol-chloroform extraction method. Using PCR-RFLP analysis, four common vitamin D receptor (VDR) polymorphisms, namely FokI, BsmI, ApaI, and TaqI, were detected. The resulting PCR products after restriction with specific enzymes that cut the alleles of each VDR polymorphism were separated using a 2% agarose gel stained with ethidium bromide. Genotype distributions and allele frequencies were compared between cases and controls, and logistic regression models were applied to evaluate the association between VDR polymorphisms and breast cancer risk. The analysis was adjusted for potential confounders, including age, BMI, and family history. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated, and a p-value of less than 0.05 was considered statistically significant

This study analyzed 150 participants, including 75 breast cancer patients and 75 age-matched healthy controls. The mean age of participants was 48.6 ± 10.4 years, with no significant age difference between cases and controls (p > 0.05). Genotyping revealed significant associations between specific vitamin D receptor (VDR) polymorphisms and breast cancer risk. The FokI TT genotype was strongly associated with increased risk (p < 0.01), whereas the ApaI AA genotype was protective (p < 0.05). Allele frequency distributions also showed significant differences between cases and controls.

Table 1 below highlights the demographic and clinical characteristics of the study population, showing similar baseline parameters between cases and controls.

Table 1: Demographic and Clinical Characteristics

Table 2 below presents the genotype distribution of the FokI polymorphism, showing a higher prevalence of the TT genotype in cases.

Table 2: FokI Genotype Distribution

Table 3 below illustrates the allele frequencies for the FokI polymorphism, indicating a significant association with breast cancer risk.

Table 3: FokI Allele Frequency

Table 4 below compares the genotype distribution of the ApaI polymorphism, showing a protective association for the AA genotype.

Table 4: ApaI Genotype Distribution

Table 5 below presents the allele frequencies for the ApaI polymorphism, with the A allele showing a protective effect.

Table 5: ApaI Allele Frequency

Table 6 below 6 highlights the genotype distribution of the BsmI polymorphism, showing no significant association with breast cancer risk.

Table 6: BsmI Genotype Distribution

Table 7 below presents the allele frequencies for the BsmI polymorphism, showing no statistically significant differences.

Table 7: BsmI Allele Frequency

Table 8 below compares the genotype distribution of the TaqI polymorphism, indicating a marginal association with breast cancer risk.

Table 8: TaqI Genotype Distribution

Table 9 below presents the allele frequencies for the TaqI polymorphism, showing a slight difference between cases and controls.

Table 9: TaqI Allele Frequency

Table 10 below summarizes the combined genotype analysis, showing additive effects of FokI TT and ApaI CC genotypes on breast cancer risk.

Table 10: Combined Genotype Analysis

This study provides substantial insight into the role of VDR polymorphisms in the modulation of risk for breast cancer [13]. Among the four polymorphisms analyzed, the FokI polymorphism showed the highest association, as the TT genotype significantly increased the susceptibility of breast cancer [14]. This finding agrees with previous research indicating that the FokI polymorphism changes the functional length of the VDR protein, which can reduce its transcriptional activity and impair the anti-carcinogenic effects of vitamin D [15].

In contrast, the ApaI polymorphism appeared to have a protective effect, and the AA genotype was significantly associated with decreased risk of breast cancer [16]. Such findings illustrate the complexity of VDR polymorphisms, since intronic variants such as ApaI can be involved in regulating gene expression by splicing or through the binding of transcription factors [17]. This protective nature of the Allele is consistent with studies showing a higher activity of VDR in its presence and could thus have an enhanced anti-proliferative and pro-apoptotic effect of vitamin D in the breast tissue [18].

Although BsmI and TaqI polymorphisms did not demonstrate any statistically significant associations in this cohort, the role of these polymorphisms in the risk of breast cancer cannot be ruled out [19. Population characteristics, environmental factors, and sample sizes may contribute to these results [20]. Combined genotype analysis further reinforced the additive effects of FokI TT and ApaI CC genotypes, suggesting that complex genetic interactions influence the risk of breast cancer rather than a single variant [21].

This study's allele frequency distributions underscore the potential impact of ethnic and geographic differences on VDR polymorphism prevalence [22]. For instance, populations with higher frequencies of protective alleles may have lower incidence of breast cancer, which would indicate a genetic predisposition influenced by evolutionary and environmental factors [23]. Such findings have clinical implications. High-risk genotypes can be detected potentially to give rise to genetic tools for early detection and targeted prevention strategies [24]. The interaction between VDR polymorphisms and vitamin D levels may also inform targeted supplementation based on genotype, maximizing the protective effects of vitamin D in at-risk populations [25, 26]. Nevertheless, this study had several limitations. It was not a case-control study, thus excluding causality [27]. The small sample size, especially with this particular study group, may further limit the generalizability of these findings [28]. Further research, especially in multi-ethnic larger cohorts and possibly in longitudinal studies, is essential to validate such associations. In functional studies about the molecular mechanism of VDR polymorphisms, much could be illuminated in the mechanism behind the process [29, 30].

This study finally shows the effects of VDR polymorphisms, such as FokI and ApaI, to be a huge risk factor in breast cancer. These results would further reinforce that genetic factors of risk must also be incorporated in the approach towards the prevention and management of breast cancer, hence further opening doors for more targeted care.

The results of this study demonstrate the role that VDR polymorphisms play in modulating the susceptibility of breast cancer. A strong association with an increased risk was shown for the FokI polymorphism, while a protective effect was indicated for the ApaI polymorphism. Analysis by combined genotypes revealed additive effects of certain polymorphisms, so it would appear there is complexity to the interaction of genetics for the modulation of breast cancer risk. These findings suggest the potential of VDR polymorphisms as genetic markers for risk stratification and personalized prevention strategies. Further research involving larger, multi-ethnic cohorts and functional studies is needed to validate these associations and reveal the underlying molecular mechanisms. Perhaps the integration of genetic insights with clinical practice will help in improving prevention and treatment outcomes for breast cancer.

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