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Zhang P, Wang R, Li Z, Wang Y, Gao C, Lv X, Song Y, Li B. The risk of smoking on multiple sclerosis: a meta-analysis based on 20,626 cases from case-control and cohort studies. PeerJ 2016; 4:e1797. [PMID: 27014514 PMCID: PMC4806598 DOI: 10.7717/peerj.1797] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/22/2016] [Indexed: 12/31/2022] Open
Abstract
Background. Multiple sclerosis (MS) has become a disease that represents a tremendous burden on patients, families, and societies. The exact etiology of MS is still unclear, but it is believed that a combination of genetic and environmental factors contribute to this disease. Although some meta-analyses on the association between smoking and MS have been previously published, a number of new studies with larger population data have published since then. Consequently, these additional critical articles need to be taken into consideration. Method. We reviewed articles by searching in PubMed and EMBASE. Both conservative and non-conservative models were used to investigate the association between smoking and the susceptibility to MS. We also explored the effect of smoking on the susceptibility to MS in strata of different genders and smoking habits. The association between passive smoking and MS was also explored. Results.The results of this study suggest that smoking is a risk factor for MS (conservative model: odds ratio (OR) 1.55, 95% CI [1.48–1.62], p < 0.001; non-conservative model: 1.57, 95% CI [1.50–1.64], p < 0.001). Smoking appears to increase the risk of MS more in men than in women and in current smokers more than in past smokers. People who exposed to passive smoking have higher risk of MS than those unexposed. Conclusion.This study demonstrated that exposure to smoking is an important risk factor for MS. People will benefit from smoking cessation, and policymakers should pay attention to the association between smoking and MS.
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Affiliation(s)
- Peng Zhang
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Rui Wang
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Zhijun Li
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Yuhan Wang
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Chunshi Gao
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Xin Lv
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Yuanyuan Song
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
| | - Bo Li
- Department of Epidemiology and Biostatistics, Jilin University School of Public Health , Changchun , China
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Ross KA. Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes. BMC Med 2011; 9:12. [PMID: 21291537 PMCID: PMC3048570 DOI: 10.1186/1741-7015-9-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 02/03/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale. METHODS A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates. RESULTS Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT. CONCLUSIONS The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.
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Affiliation(s)
- Kenneth Andrew Ross
- Department of Computer Science, Columbia University, New York, NY 10027, USA.
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Handel AE, Williamson AJ, Disanto G, Dobson R, Giovannoni G, Ramagopalan SV. Smoking and multiple sclerosis: an updated meta-analysis. PLoS One 2011; 6:e16149. [PMID: 21249154 PMCID: PMC3020969 DOI: 10.1371/journal.pone.0016149] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 12/14/2010] [Indexed: 01/29/2023] Open
Abstract
Background Multiple sclerosis (MS) is a leading cause of disability in young adults. Susceptibility to MS is determined by environmental exposure on the background of genetic risk factors. A previous meta-analysis suggested that smoking was an important risk factor for MS but many other studies have been published since then. Methods/Principal Findings We performed a Medline search to identify articles published that investigated MS risk following cigarette smoking. A total of 14 articles were included in this study. This represented data on 3,052 cases and 457,619 controls. We analysed these studies in both a conservative (limiting our analysis to only those where smoking behaviour was described prior to disease onset) and non-conservative manner. Our results show that smoking is associated with MS susceptibility (conservative: risk ratio (RR) 1.48, 95% confidence interval (CI) 1.35–1.63, p<10−15; non-conservative: RR 1.52, 95% CI 1.39–1.66, p<10−19). We also analysed 4 studies reporting risk of secondary progression in MS and found that this fell just short of statistical significance with considerable heterogeneity (RR 1.88, 95% CI 0.98–3.61, p = 0.06). Discussion Our results demonstrate that cigarette smoking is important in determining MS susceptibility but the effect on the progression of disease is less certain. Further work is needed to understand the mechanism behind this association and how smoking integrates with other established risk factors.
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Affiliation(s)
- Adam E. Handel
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom
| | - Alexander J. Williamson
- Department of Physical and Theoretical Chemistry, University of Oxford, Oxford, United Kingdom
| | - Giulio Disanto
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom
| | - Ruth Dobson
- Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, London, United Kingdom
| | - Gavin Giovannoni
- Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, London, United Kingdom
- * E-mail: (GG); (SVR)
| | - Sreeram V. Ramagopalan
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom
- Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, London, United Kingdom
- * E-mail: (GG); (SVR)
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Petcu I, Savu D, Thierens H, Nagels G, Vral A. In vitroradiosensitivity of peripheral blood lymphocytes in multiple sclerosis patients. Int J Radiat Biol 2009; 82:793-803. [PMID: 17148263 DOI: 10.1080/09553000600932976] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To assess the in vitro radiosensitivity of peripheral blood lymphocytes of secondary progressive multiple sclerosis (MS) patients in comparison to healthy individuals. MATERIAL AND METHODS Radiosensitivity of MS patients lymphocytes to in vitro irradiation of 2 Gy 60Co gamma-rays was studied in whole blood cultures and separated peripheral blood mononuclear cell (PBMC) cultures. Chromosomal radiosensitivity was investigated by means of the G0-micronucleus (MN) assay. The radio-induction of micronuclei was also studied in separated subsets of CD4+ (helper) and CD8+ (suppressor) T cells. Apoptosis was analysed in PBMC cultures using fluorescence microscopy techniques. RESULTS The spontaneous MN induction was significantly higher in MS patients compared to healthy controls for whole blood and PBMC cultures. After gamma-irradiation of whole blood cultures no difference in radiosensitivity was observed between patients and controls for MN induction. In irradiated PBMC cultures, the CD4+ lymphocytes of MS patients were less radiosensitive compared to healthy controls and this more resistant behaviour increased with increasing illness duration. Radiation induced apoptosis in G0 lymphocytes of MS patients was lower than in controls. CONCLUSION After gamma irradiation, a radioresistant behaviour in PBMC cultures of MS patients was revealed. This radioresistant behaviour was expressed by lower MN induction in CD4+ lymphocytes and by lower apoptosis induction in G0 PBMC cultures and may point to an adaptive response. The higher radiation response in whole blood cultures compared to PBMC cultures was significantly more pronounced in MS patients, suggesting special characteristics of the whole blood environment associated with this pathology.
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Affiliation(s)
- Ileana Petcu
- Department of Environmental and Life Physics, National Institute for Physics and Nuclear Engineering Horia Hulubei, Bucharest, Romania
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Petcu I, Savu D, Vral A, Thierens H, Nagels G, De Ridder L. Chromosomal Radiosensitivity in Secondary‐Progressive Multiple Sclerosis Patients. Int J Radiat Biol 2009; 80:663-72. [PMID: 15586886 DOI: 10.1080/09553000400007664] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE To investigate chromosomal radiosensitivity of secondary progressive (SP) multiple sclerosis (MS) patients in comparison to a group of healthy individuals. MATERIAL AND METHODS Chromosomal radiosensitivity was assessed in vitro with the G2 assay and the G0-micronucleus (MN) assay. For the G2 assay phytohaemagglutinin (PHA) stimulated blood cultures were irradiated with a dose of 0.4 Gy 60Co gamma rays in the G2 phase of the cell cycle. For the MN assay unstimulated diluted blood samples were exposed to 3.5 Gy 60Co gamma rays delivered at a high dose-rate (HDR = 1 Gy/min) or low dose-rate (LDR = 4 mGy/min). RESULTS No significant differences in the number of chromatid breaks were observed between MS patients and healthy individuals. With the G0-MN assay a higher spontaneous MN yield was found in MS patients. At HDR irradiation no significant differences were shown, while at LDR irradiation, MS patients were found less sensitive than healthy controls. The dose-rate sparing index was higher for MS patients, pointing to a better repair capacity. CONCLUSIONS MS patients are not characterised by an enhanced in vitro chromosomal radiosensitivity. The radioresistant response, which was only observed with the MN assay after LDR irradiation, may point to an adaptive response induced by in vivo oxidative stress in SPMS patients.
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Affiliation(s)
- Ileana Petcu
- Department of Environmental and Life Physics, National Institute for Physics and Nuclear Engineering Horia Hulubei, 407 Atomistilor St., R-76900 Bucharest-Magurele, Romania
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Kang MH, Genser D, Elmadfa I. Increased sister chromatid exchanges in peripheral lymphocytes of patients with Crohn's disease. Mutat Res 1997; 381:141-8. [PMID: 9403040 DOI: 10.1016/s0027-5107(97)00161-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A cytogenetic study was performed using Crohn's disease patients to determine whether the presence of chromosome instability is related to Crohn's disease, a chronic inflammatory bowel disease. Sister chromatid exchange (SCE) frequencies in peripheral blood lymphocyte cultures from 22 Crohn's disease patients and an equal number of healthy controls matched for sex and age were analyzed. The mean of SCE frequency in Crohn's disease patients was 11.64 +/- 0.42 (SEM) per cell, which was significantly higher than the value of 8.38 +/- 0.22 per cell in the matched controls (p < 0.0001). The Crohn's disease patients showed significantly increased high frequency cells (HFC) as compared to those among the matched controls. There was a significant correlation between HFC frequencies of the Crohn's disease patients and the severity of their disease as determined by the number of relapses per year and the degree of chronic activity after adjusting for the smoking status (r = 0.54, p = 0.011). In both smokers and non-smokers, the mean SCE and HFC frequencies of the patients were significantly higher than those of the controls. These results suggest that Crohn's disease is a condition with increased chromosome instability characterized by a high level of SCE frequencies which are associated with the inflammatory condition itself.
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Affiliation(s)
- M H Kang
- Department of Food and Nutrition, Han Nam University, Taejon, South Korea
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Abstract
There has been increasing evidence that genetic factors have a role in determining susceptibility to MS. Re-examination of results from prevalence and migration surveys reveals that there remains considerable ambiguity in interpretation. Some patterns previously thought to decisively support environmental determination may still be explained, at least in part, on a genetic basis. It seems inescapable that MS is probably due to an interaction of genetic and environmental factors. It remains undetermined whether or not genes exist which are truly necessary for the development of the disease. Existing data are consistent with the notion that the study of MS susceptibility will parallel the findings in experimental models of spontaneous autoimmunity and that at very least, two genes and almost certainly several genes will be found to influence susceptibility and interact in as yet unknown ways. One of these loci appears to be the Class II MHC, although its role may be minor at the germ line level. Roles for the T-cell receptor alpha and beta loci appear to be minor and may even be non-existent in contributing to heritable susceptibility. We predict that additional loci will be identified which influence both susceptibility and outcome and will be more important. Furthermore, it is clear that the understanding of the contribution of individual susceptibility loci will continue to be difficult because of the constraints of human pedigree data. It is likely that further resolution of the questions posed above related to genetic susceptibility in MS will require multicenter collaboration.
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Affiliation(s)
- G C Ebers
- Multiple Sclerosis Clinic, University of Western Ontario, University Hospital, London, Canada
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Hamamy H, Shubber EK, al-Allak BM. Sister chromatid exchange frequencies in a group of individuals with unfavorable reproductive health. Eur J Obstet Gynecol Reprod Biol 1992; 43:45-9. [PMID: 1737608 DOI: 10.1016/0028-2243(92)90242-q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sister chromatid exchange (SCE) frequencies and other cytogenetic parameters were investigated in peripheral blood lymphocytes from 92 subjects comprising 44 parents of malformed offspring or repeated fetal wastage (Group I) and 48 controls, age and sex matched, having normal reproductive health (Group II). The karyotypes were normal and the mean mitotic indices were comparable in both groups. The mean frequency of SCE per metaphase in Group I (8.67 +/- 0.32) was significantly higher than the mean for group II (6.65 +/- 0.16), and the cellular replicative index in Group I (1.78 +/- 0.04) was significantly different from that of Group II (1.66 +/- 0.03). The results are discussed in the light of the present understanding of the etiology and mechanism of production of sister chromatid exchanges.
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Affiliation(s)
- H Hamamy
- Department of Pathology, Al-Mustansiriya Medical College, Baghdad, Iraq
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D'Alessandro E, Di Cola M, Lo Re ML, Ligas C, Vaccarella C, D'Andrea F, Marini C, Prencipe M. Nonrandom chromosome changes in multiple sclerosis. AMERICAN JOURNAL OF MEDICAL GENETICS 1990; 37:406-11. [PMID: 2260573 DOI: 10.1002/ajmg.1320370322] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In order to study the role of genetic factors in multiple sclerosis, cytogenetic analysis was performed on 48 patients with the clinically defined disease. We found a high incidence of subjects (50%) with abnormal chromosomes, showing premature centromere division of the X chromosome and structural aberrations, translocations, or deletions that could suggest preferential breakpoints. Correlation between clinical and cytogenetic data showed that cytogenetic abnormalities were more common in patients with high frequency of relapse or with a progressive form of the disease.
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Affiliation(s)
- E D'Alessandro
- Cattedra di Genetica Medica, Università degli Studi, L'Aquila, Italy
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Ammenheuser MM, Ward JB, Whorton EB, Killian JM, Legator MS. Elevated frequencies of 6-thioguanine-resistant lymphocytes in multiple sclerosis patients treated with cyclophosphamide: a prospective study. Mutat Res 1988; 204:509-20. [PMID: 3347218 DOI: 10.1016/0165-1218(88)90045-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
An autoradiographic assay for 6-thioguanine-resistant (TGr) lymphocytes was used to determine the frequency of in vivo derived variant T lymphocytes in peripheral blood from multiple sclerosis (MS) patients treated with monthly intravenous infusions of 750 mg/m2 of cyclophosphamide (CP). To analyze the time-course of response to CP, the MS patients were studied prospectively. Samples were obtained from the patients before the beginning of CP therapy, 4-5 times during the course of treatment, and, finally, 2 or 3 months after the completion of therapy. 2 weeks after the first CP infusion, the variant frequencies (Vfs) of the MS patients were significantly increased (p less than 0.05) above their pre-treatment values, but by 4 weeks following the first CP infusion the Vfs had fallen to normal or near-normal levels. After subsequent treatments, the frequencies of variant TGr cells were again higher than pre-treatment Vfs. However, within 7-13 weeks after the cessation of CP therapy, the Vfs of all subjects had returned to normal levels. The transient nature of the response indicates rapid in vivo selection against CP-induced TGr mutant cells. The mean pre-treatment Vf of the 4 MS patients who were cigarette smokers was 6.56 X 10(-6) which was significantly greater (p less than 0.05) than the mean Vf (1.52 X 10(-6) of the 4 MS patients who were non-smokers. The mean Vf from 8 assays of healthy non-smokers was 1.92 X 10(-6).
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Affiliation(s)
- M M Ammenheuser
- Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston 77550
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