Association of CYP1A1 A4889G and T6235C polymorphisms with the risk of sporadic breast cancer in Brazilian women

OBJECTIVES:We examined the influence of CYP1A1 A4889G and T6235C polymorphisms on the risk of sporadic breast cancer.METHODS:DNA from 742 sporadic breast cancer patients and 742 controls was analyzed using the polymerase chain reaction, followed by the restriction fragment length polymorphism technique.RESULTS:More patients had the CYP1A1 4889AG+GG genotype compared to controls (29.0% versus 23.2%, p=0.004). The G allele carriers had a 1.50-fold increased risk (95% CI: 1.14-1.97) of sporadic breast cancer compared to the other study participants. The frequency of the 4889AG+GG genotype among the Caucasian patients was higher than in the non-Caucasian patients (30.4% versus 20.2%, p=0.03) and controls (30.4% versus 23.2%, p=0.002). Caucasians and G allele carriers had a 1.61-fold increased risk (95% CI: 1.20-2.15) of sporadic breast cancer compared to other subjects. The CYP1A1 4889AG+GG genotype was more common among patients with a younger median age at first full-term pregnancy than among controls (33.8% versus 23.2%, p=0.001) and subjects whose first full-term pregnancies occurred at an older age (33.8% versus 26.1%, p=0.03). Women with the CYP1A1 4889AG+GG genotype and earlier first full-term pregnancies had a 1.87-fold (95% CI: 1.32-2.67) increased risk of sporadic breast cancer compared to the other study participants. Excess CYP1A1 4889AG+GG (39.8% versus27.1%, p=0.01) and 6235TC+CC (48.4% versus 35.9%, p=0.02) genotypes were also observed in patients with grade I and II tumors compared to patients with grade III tumors and controls (39.8% versus 23.2%, p=0.04; 48.4% versus 38.6%, p=0.04). The G and C allele carriers had a 2.44-fold (95% CI: 1.48-4.02) and 1.67-fold (95% CI: 1.03-2.69) increased risk, respectively, of developing grade I and II tumors compared to other subjects.CONCLUSIONS:The CYP1A1 A4889G and T6235C polymorphisms may alter the risk of sporadic breast cancer in Brazilian women.

Glutathione S-transferase mu 1 (GSTM1) and theta 1 (GSTT1) genetic polymorphisms and atopic asthma in children from Southeastern Brazil

Xenobiotics can trigger degranulation of eosinophils and mast cells. In this process, the cells release several substances leading to bronchial hyperactivity, the main feature of atopic asthma (AA). GSTM1 and GSTT1 genes encode enzymes involved in the inactivation of these compounds. Both genes are polymorphic in humans and have a null variant genotype in which both the gene and corresponding enzyme are absent. An increased risk for disease in individuals with the null GST genotypes is therefore, but this issue is controversial. The aim of this study was to investigate the influence of the GSTM1 and GSTT1 genotypes on the occurrence of AA, as well as on its clinical manifestations. Genomic DNA from 86 patients and 258 controls was analyzed by polymerase chain reaction. The frequency of the GSTM1 null genotype in patients was higher than that found in controls (60.5 percent versus 40.3 percent, p = 0.002). In individuals with the GSTM1 null genotype the risk of manifested AA was 2.3-fold higher (95 percentCI: 1.4-3.7) than for others. In contrast, similar frequencies of GSTT1 null and combined GSTM1 plus GSTT1 null genotypes were seen in both groups. No differences in genotype frequencies were perceived in patients stratified by age, gender, ethnic origin, and severity of the disease. These results suggest that the inherited absence of the GSTM1 metabolic pathway may alter the risk of AA in southeastern Brazilian children, although this must be confirmed by further studies with a larger cohort of patients and age-matched controls from the distinct regions of the country.

No contribution of GSTM1 and GSTT1 null genotypes to the risk of neutropenia due to benzene exposure in Southeastern Brazil

Exposure to benzene has been associated with haematological diseases such as neutropenia (NEB) and acute myeloid leukaemia (AML). We tested whether the null genotypes of the GSTM1 and GSTT1 genes, involved in benzene inactivation, altered the risk for NEB in southeastern Brazil. Genomic DNA from 55 NEB patients and 330 controls was analysed by multiplex-polymerase chain reaction. The frequency of the GSTM1, GSTT1 and combined null genotypes was similar in patients and controls (GSTM1, 27.3 percent vs. 38.8 percent, p = 0.16; GSTT1, 25.5 percent vs. 19.7 percent, p = 0.24; GSTM1/GSTT1, 12.7 percent vs. 6.7 percent, p = 0.26; respectively). The distribution of genotype classes in NEB patients was similar to normal controls, suggesting that GSTM1 and GSTT1 null genotypes make no specific contribution to the risk of NEB. As the GSTM1 and GSTT1 null genotypes were previously associated with increased risk for AML in Brazil and elsewhere, we hypothesise that different thresholds of chemical exposure relative to distinct GSTM1 and GSTT1 genotypes may determine whether AML or NEB manifests in benzene exposed individuals from southeastern Brazil. Although indicative, our results still require support by prospective and large scale epidemiological studies, with rigorous assessment of daily chemical exposures and control of the possible contribution of other polymorphic genes involved in benzene metabolism.

Características mamográficas do câncer de mama associadas aos polimorfismos GSTM1 e GSTT1 / Polymorphisms GSTM1 and GSTT1 and sporadic breast cancer mammographic features

INTRODUÇÃO: As enzimas do sistema da glutationa S-transferase (GST) modulam os efeitos da exposição a vários agentes citotóxicos e genotóxicos. Os genes GSTM1 e GSTT1 são polimórficos em humanos e suas deleções têm sido associadas ao aumento do risco de várias neoplasias, dentre elas o câncer de mama. OBJETIVO: Comparar a freqüência das deleções dos genes GSTM1 e GSTT1 em mulheres sadias e com câncer de mama e comparar as características mamográficas do câncer entre mulheres portadoras e não portadoras das referidas deleções. MÉTODOS: Foram determinadas as freqüências das referidas deleções por PCR em 100 pacientes portadoras de câncer de mama esporádico tratadas de setembro de 2004 a junho de 2005 e em 169 mulheres sadias doadoras de sangue no mesmo período e comparadas através do odds ratio (OR) com seus respectivos IC 95 por cento. Foram revistos os prontuários e as mamografias das pacientes com câncer e avaliadas características mamográficas (padrão de distribuição do parênquima fibro-glandular, achados mamográficos ao diagnóstico e classificação BI-RADS), correlacionando-as às deleções gênicas através do cálculo da RP (razão de prevalência) com seus respectivos IC 95 por cento. RESULTADOS: O GSTM1 esteve deletado em 40 por cento dos cânceres e em 44,4 por cento dos controles (OR=1,20; IC 95 por cento 0,70-2,04; p=0,5659) enquanto o GSTT1 em 20 por cento e 19,5 por cento, respectivamente (OR=0,73; IC 0,37-1,44; p=0,4124). O padrão mamográfico denso esteve associado à deleção homozigótica do GSTM1 (RP= 2,43; IC 1,11-4,08). Não se observou associação entre as deleções do sistema GST e achados mamográficos ao diagnóstico e classificação BI-RADS. CONCLUSÃO: A deleção homozigótica do gene GSTM1 associou-se ao padrão mamográfico denso.

INTRODUCTION: Enzymes of the Glutathione S-transferase system (GST) modulate the effects of exposure to several cytotoxic and genotoxic agents. The GSTM1 and GSTT1 genes are polymorphic in humans and their deletions have been associated to increased risk of many cancers, including breast cancer. OBJECTIVE: To evaluate the occurrence of homozygous deletions of the GSTM1 and GSTT1 genes in women with sporadic breast cancer and in women without cancer and to compare breast cancer mammographic features between patients with and without these deletions. METHODS: The study evaluated 100 patients with sporadic breast cancer treated from September 2004 to June 2005 and 169 women without cancer, determining the frequency of the above-mentioned deletions by PCR and calculating the odds ratios and their 95 percent confidence intervals. Medical files and mammograms of 100 patients with breast cancer were evaluated and correlated with mammographic features such as density, mammographic findings and the BI-RADS classification. These findings were correlated with the genetic deletions by the PR (Prevalence-Ratio) with their respective 95 percent confidence intervals. RESULTS: The GSTM1 gene was deleted in 40 percent of the cancers and in 44.4 percent of controls (OR = 1.20; CI 95 percent 0.70 - 2.04; p=0.5659) while the GSTT1 gene was deleted in 20 percent and 19.5 percent, respectively (OR = 0.73; CI 95 percent 0.37-1.44; p=0.4124). High mammographic density had been associated with GSTM1 deletion (PR 2.43; CI 1.11 to 4.08). GST deletions were not associated with predominant mammographic findings and the BI-RADS classification. CONCLUSION: GSTM1 homozygous deletion was associated with high mammographic density.

Molecular analysis of the most prevalent mutations of the FANCA and FANCC genes in Brazilian patients with Fanconi anaemia

Fanconi anaemia (FA) is a recessive autosomal disease determined by mutations in genes of at least eleven complementation groups, with distinct distributions in different populations. As far as we know, there are no reports regarding the molecular characterisation of the disease in unselected FA patients in Brazil. OBECTIVE: This study aimed to investigate the most prevalent mutations of FANCA and FANCC genes in Brazilian patients with FA. METHODS: Genomic DNA obtained from 22 racially and ethnically diverse unrelated FA patients (mean age ± SD: 14.0 ± 7.8 years; 10 male, 12 female; 14 white, 8 black) was analysed by polymerase chain reaction and restriction site assays for identification of FANCA (delta3788-3790) and FANCC (delta322G, IVS4+4A -> T, W22X, L496R, R548X, Q13X, R185X, and L554P) gene mutations. RESULTS: Mutations in FANCA and FANCC genes were identified in 6 (27.3 percent) and 14 (63.6 percent) out of 22 patients, respectively. The disease could not be attributed to the tested mutations in the two remaining patients enrolled in the study (9.1 percent). The registry of the two most prevalent gene abnormalities (delta3788-3790 and IVS4 + 4 -> T) revealed that they were present in 18.2 percent and 15.9 percent of the FA alleles, respectively. Additional FANCC gene mutations were found in the study, with the following prevalence: delta322G (11.4 percent), W22X (9.1 percent), Q13X (2.3 percent), L554P (2.3 percent), and R548X (2.3 percent) of total FA alleles. CONCLUSION: These results suggest that mutations of FANCA and FANCC genes are the most prevalent mutations among FA patients in Brazil.