Lack of an association between CYP1A1 gene Ile462Val polymorphism and polycystic ovary syndrome in Chinese

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Potential environmental toxicant exposure, metabolizing gene variants and risk of PCOS-A systematic review

Exposure of environmental toxicants such as potentially toxic metals and pesticides have largely been attributed to produce adverse effects on general women's health and to be more precise on the reproductive system. In order to explore exposure of toxicants and metabolizing gene variants as risk factor for polycystic ovarian syndrome (PCOS), literature search was carried out using the databases PubMed, Central Cochrane Library, Google Scholar, Science Direct with appropriate keywords upto 6 December 2020. While most of the studies indicate higher serum Cu concentration and lower concentration of Mn as risk factor, studies also report presence of higher pesticide concentration in PCOS women. Genes such as MTHFR, CYPs participate in the metabolism of toxicants and may show different response due to underlying genetic variants. Thus, toxicant exposure are to some extent responsible for the pathogenesis of syndrome through oxidative stress and endocrine disruption, but the susceptibility may vary due to the underlying genetic polymorphism of the exposed population.

CYP1A1 gene (6235T<C) polymorphism as a risk factor for polycystic ovarian syndrome among Egyptian women

This case-control study was carried out to examine the association between CYP1A1 gene (6235T<C) polymorphism among Egyptian women with polycystic ovarian syndrome (PCOS). One hundred and twenty women with PCOS, as well as 120 apparently healthy women as controls, were included in this study. Blood samples were collected on the second or third day of the menstrual cycle for laboratory work-up. CYP1A1 gene (6235T<C) polymorphism was determined using restriction enzyme fragment length polymorphism - polymerase chain reaction (RFLP-PCR) technique. Women who carried the TC and CC genotypes showed insignificant increase in risk (1.4 and 2.7, respectively) for developing PCOS (p = 0.331 and p = 0.124, respectively). The risk showed a significant association among PCOS women with ovarian sonographic stigmata of polycystic ovaries (PCO) who carried the TC genotype (Odds Ratio (OR) = 1.92, p = 0.032), as well as among carriers of the CC genotype (OR = 4.2, p = 0.048). Both TC and CC genotypes were significantly associated with the ovarian volume (p < 0.001) and abdominal obesity (p = 0.025), while no associations were shown with the hormonal profile. In conclusion, both TC and CC genotypes of the CYP1A1 gene showed increased susceptibility to PCOS. CYP1A1 gene polymorphism may affect the folliculogenesis and the hormonal status along with other risk factors leading to the development of the full picture of PCOS.

CYP1A1 and GSTP1 gene variations in breast cancer: a systematic review and case-control study

In first part of this study, a systematic review was designed to explore the involvement of CYP1A1 and GSTP1 genes in breast cancerogenesis. Based on systematic review, we designed a study to screen CYP1A1 and GSTP1 genes for mutation and their possible association with breast carcinogenesis. A total of 400 individuals were collected and analyzed by PCR-SSCP. After sequence analysis of coding region of CYP1A1 we identified eleven mutations in different exons of respective gene. Among these eleven mutations, ~3 folds increased breast cancer risk was found associated with Asp82Glu mutation (OR 2.99; 95% CI 1.26-7.09), with Ser83Thr mutation (OR 2.99; 95% CI 1.26-7.09) and with Glu86Ala mutation (OR 3.18; 95% CI 1.27-7.93) in cancer patients compared to controls. Furthermore, ~4 folds increase in breast cancer risk was found associated with Asp347Glu, Phe398Tyr and 5178delT mutations (OR 3.92; 95% CI 1.35-11.3) in patients compared to controls. The sequence analysis of GSTP1 resulted in identification of total five mutations. Among these five mutations, ~3 folds increase in breast cancer risk was observed associated with 1860G>A mutation, with 1861-1876delCAGCCCTCTGGAGTGG mutation (OR 2.70; 95% CI 1.10-6.62) and with 1861C>A mutation (OR 2.97; 95% CI 1.01-8.45) in cancer patients compared to controls. Furthermore, ~5 folds increase in breast cancer risk was associated with 1883G>T mutation (OR 4.75; 95% CI 1.46-15.3) and ~6 folds increase in breast cancer risk was found associated with Iso105Val mutation (OR 6.43; 95% CI 1.41-29.3) in cancer patients compared to controls. Our finding, based on systematic review and experimental data suggest that the polymorphic CYP1A1 and GSTP1 genes may contribute to risk of developing breast cancer.

Common polymorphisms in the CYP1A1 and CYP11A1 genes and polycystic ovary syndrome risk: a meta-analysis and meta-regression

AIM

Increasing scientific evidences suggest that common polymorphisms in the CYP1A1 and CYP11A1 genes may contribute to the development and progression of polycystic ovary syndrome (PCOS), but many existing studies have yielded inconclusive results. The aim of this study was to perform a meta-analysis of published studies on the associations between common polymorphisms in the CYP1A1 and CYP11A1 genes and susceptibility to PCOS.

METHODS

An extensive literature search for relevant studies was conducted on PubMed, Embase, Web of Science, Cochrane Library, and CBM databases from their inception through 1 June, 2013. This meta-analysis was performed using the STATA 12.0 software. The crude risk ratio (RR) with 95% confidence interval was calculated.

RESULTS

Thirteen case-control studies were included in this meta-analysis with a total of 1,571 PCOS cases and 1,918 healthy controls. Our meta-analysis revealed that CYP1A1 MspI (rs4646903 T > C) polymorphism may increase the risk of PCOS, especially among Caucasian populations. Furthermore, CYP11A1 microsatellite [TTTA]n repeat polymorphism also showed significant associations with increased risk of PCOS among Caucasian populations. However, there was no statistically significant association between CYP1A1 Ile462Val (rs1048943 A > G) polymorphism and PCOS risk.

CONCLUSION

Our meta-analysis suggests that CYP1A1 MspI and CYP11A1 microsatellite [TTTA]n repeat polymorphisms may contribute to increasing susceptibility to PCOS among Caucasian populations. Detection of common polymorphisms in the CYP1A1 and CYP11A1 genes might be promising biomarkers for the diagnosis and prognosis of PCOS.

CYP1A1 gene polymorphisms and polycystic ovary syndrome risk: a meta-analysis and meta-regression

AIMS

Emerging evidence suggests that common functional polymorphisms in the CYP1A1 gene are involved in the regulation of the activities of cytochrome P450 enzymes, thereby increasing an individual's susceptibility to polycystic ovary syndrome (PCOS), but individually published results are inconclusive. This meta-analysis aimed to derive a more precise estimation of the relationship between CYP1A1 gene polymorphisms and PCOS risk.

METHODS

A literature search of PubMed, Embase, Web of Science, the Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Bio-medicine Database, and Chinese Sci-tech Journals Database (VIP) databases was conducted from inception to March 1, 2013. The crude odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Five case-control studies were included with a total of 1,036 subjects, including 521 PCOS cases and 515 healthy controls. Our meta-analysis results indicated that the C variant of the CYP1A1 rs4646903 (T>C) polymorphism was associated with an increased risk of PCOS (allele model: OR=1.62, 95% CI: 1.06-2.48, P=0.025; dominant model: OR=2.37, 95% CI: 1.25-4.48, P=0.008; homozygous model: OR=2.52, 95% CI: 1.17-5.44, P=0.019), especially among the general female population in Turkey and India. However, there was no statistically significant association between the CYP1A1 rs1048943 (A>G) polymorphism and PCOS risk (all P>0.05). No publication bias was detected in this meta-analysis.

CONCLUSION

The current meta-analysis indicates that the CYP1A1 rs4646903 (T>C) polymorphism may contribute to increasing susceptibility to PCOS, especially among the general female population in Turkey and India. However, further studies are still needed to accurately determine whether the CYP1A1 rs1048943 (A>G) polymorphism is associated with PCOS risk.

CYP1A1 polymorphism in adolescents with polycystic ovary syndrome

OBJECTIVE

To evaluate the rates of the CYP1A1 Ile/Val polymorphism in Turkish adolescent females.

METHODS

The CYP1A1 Ile/Val polymorphism was analyzed by collecting DNA samples from 44 adolescents with polycystic ovary syndrome (PCOS)--according to the Rotterdam criteria--and 120 healthy female controls aged 13-18 years in Ankara, Turkey.

RESULTS

There was a 2.5-fold increase in the frequency of the CYP1A1 Ile/Val genotype in adolescents with PCOS compared with the control group (odds ratio [OR] 2.54; 95% confidence interval [CI], 1.143-5.637; P<0.001), in addition to a 2.4-fold increase in the frequency of the Val allele (OR 2.43; 95% CI, 1.099-5.397; P<0.001).

CONCLUSION

The data show an association between CYP1A1 and PCOS, indicating that variant alleles of the gene may affect the metabolic and transport pathway of estrogens, thus causing PCOS.

The rules of variation: amino acid exchange according to the rotating circular genetic code

General guidelines for the molecular basis of functional variation are presented while focused on the rotating circular genetic code and allowable exchanges that make it resistant to genetic diseases under normal conditions. The rules of variation, bioinformatics aids for preventative medicine, are: (1) same position in the four quadrants for hydrophobic codons, (2) same or contiguous position in two quadrants for synonymous or related codons, and (3) same quadrant for equivalent codons. To preserve protein function, amino acid exchange according to the first rule takes into account the positional homology of essential hydrophobic amino acids with every codon with a central uracil in the four quadrants, the second rule includes codons for identical, acidic, or their amidic amino acids present in two quadrants, and the third rule, the smaller, aromatic, stop codons, and basic amino acids, each in proximity within a 90 degree angle. I also define codifying genes and palindromati, CTCGTGCCGAATTCGGCACGAG.