Association of genetic variants rs641153 (CFB), rs2230199 (C3), and rs1410996 (CFH) with age-related macular degeneration in a Brazilian population

This study aimed to investigate the association among genetic variants of the complement pathway CFB R32Q (rs641153), C3 R102G (rs2230199), and CFH (rs1410996) with age-related macular degeneration (AMD) in a sample of the Brazilian population. In a case-control study, 484 AMD patients were classified according to the clinical age-related maculopathy grading system (CARMS) and compared to 479 unrelated controls. The genetic variants rs1410996 of complement H (CFH), rs641153 of complement factor B (CFB), and rs2230199 of complement 3 (C3) were evaluated through polymerase chain reaction (PCR) and direct sequencing. The associations between single nucleotide polymorphisms (SNPs) and AMD, adjusted by age, were assessed by using logistic regression models. A statistically significant association was observed between AMD risk and rs2230199 variant with an OR of 2.01 (P  = 0.0002) for CG individuals compared to CC individuals. Regarding the comparison of advanced AMD versus the control group, the OR was 2.12 (P = 0.0036) for GG versus AA genotypes for rs1410996 variant. Similarly, the OR for rs2230199 polymorphism was 2.3034 (P  = 5.47^e-05) when comparing CG individuals to CC carriers. In contrast, the rs641153 variant showed a significant protective effect against advanced AMD for GA versus GG genotype (OR = 0.4406; P  = 0.0019). When comparing wet AMD versus controls, a significant association was detected for rs1410996 variant (OR = 2.16; P  = 0.0039) comparing carriers of the homozygous GG versus AA genotype, as well as in the comparisons of GG (OR = 3.0713; P  = 0.0046) and CG genotypes (OR = 2.2249; P  = 0.0002) versus CC genotype for rs2230199 variant, respectively. The rs641153 variant granted a significant protective effect against wet AMD for GA versus GG genotypes (OR = 0.4601; P  = 0.0044). Our study confirmed the risk association between rs2230199 and rs1410996 variants and AMD, and the protective role against AMD for rs641153 variant.     

Analysis of XPD genetic polymorphisms of esophageal squamous cell carcinoma in a population of Yili Prefecture, in Xinjiang, China

To evaluate the association with genetic polymorphisms in Xeroderma pigmentosum complementation group D (XPD) gene of esophageal squamous cell carcinoma (ESCC) risk in a population of Yili Prefecture, in Xinjiang, China. A hospital-based case–control study was designed with 571 samples including 213 ESCC patients and 358 controls with age, gender and ethnicity-matched subjects (Kazakh, Uygur and Han ethnic). Genotypes were determined by PCR restriction fragment length polymorphism (PCR-RLFP) and confirmed by sequence. Relative risk associated with a particular genotype was estimated by calculating odds ratios (OR) along with 95% confidence intervals (CI). Significant ESCC risk was observed for XPD Lys751Gln (rs13181) frequency of presence C allele (OR: 1.409, 95% CI: 1.005–1.976) in the three ethnics. XPD Asp312Asn (rs1799793) of Han ethnic was associated with a borderline decrease of ESCC (OR: 0.362, 95% CI: 0.145–0.906), however, it was associated with ESCC risk in Uygur ethnic (OR: 2.403, 95% CI: 1.087–5.310). The results demonstrated an association between the XPD Lys751Gln (rs13181) for frequency of presence C allele and risk for ESCC in the three ethnics of Yili Prefecture, in Xinjiang, China. XPD Asp312Asn (rs1799793), which was associated with a borderline decrease of Han ethnic and risk of Uygur ethnic of ESCC, may play a different role in the three ethnics of ESCC.     

Methylenetetrahydrofolate reductase gene polymorphisms in 13 Chinese ethnic populations

It has been shown that the polymorphisms of Methylenetetrahydrofolate reductase (MTHFR) gene are associated with susceptibility to several disorders including hyperhomocysteinemia, vascular disease, birth defect, and certain cancers, and exhibit great diversities among various populations. The aim of this study was to investigate the prevalence of two common non-synonymous single nucleotide polymorphisms (i.e., C677T and A1298C) at MTHFR gene in 13 Chinese populations. A total of 1015 healthy individuals from 13 populations distributed widely from north to south in China were studied. DNA samples were isolated from peripheral blood samples and genotyped using polymerase chain reaction-restriction fragment length polymorphism. For C677T polymorphism, the frequency in Chinese of CC homozygous was 42.4%; CT heterozygous was 49.8%; and TT homozygous was 7.9%. For A1298C, AA homozygous was 39.2%; AC heterozygous was 38.6%; and CC homozygous was 22.2%. The allelic frequency of 677T and 1298C was 32.8 and 41.5%, respectively, and each allele frequency had significant variance in 13 Chinese populations. The frequency of the 677T allele among southern populations was 30.7% compared to 38.0% among northeastern and 30.5% among northwestern populations. The difference was statistically significant (p < 0.01). The frequency of 1298C mutation in southerns was 58.9% whereas in northeasterns it was 24.0% and 37.6% in northwesterns. This was also statistically significant (p < 0.01). The MTHFR C677T and A1298C sites were in linkage disequilibrium in the Chinese population revealed by our data.     

The prevalence of CD33 and MS4A6A variant in Chinese Han population with Alzheimer's disease

CD33 and MS4A6A genes play potential key roles in the pathogenesis of Alzheimer's disease (AD). One recent genome-wide association study has revealed that the rs3865444 polymorphism in the CD33 gene and rs610932 polymorphism in the MS4A6A gene are associated with susceptibility to AD in Caucasians. To evaluate the relationship between the polymorphism of the CD33, MS4A6A gene and AD in the ethnic Chinese Han, we conducted a case-control study (n = 383, age > 54) to determine the prevalence of single-nucleotide polymorphism of two genes in patients with AD in Chinese population of Mainland, and clarified whether these polymorphisms are risk factors for AD. The prevalence of the allele (T) in the rs3865444 polymorphism of the CD33 gene and allele (C) in rs610932 polymorphism of the MS4A6A gene was significantly different in AD patients and control subjects (P < 0.001, respectively), and the results were not influenced by age, gender, or APOE status. Our data revealed the allele (T) of the rs3865444 polymorphism of the CD33 gene and the allele (C) of the rs610932 polymorphism of the MS4A6A gene may contribute to AD risk in the Chinese Han population.     

广西壮族人群EBI3 基因rs6613A/T, rs4905A/G多态性分布特点

目的:分析广西壮族人群EBI3基因rs6613A/T、rs4905A/G多态性分布特点。方法:采用单碱基延伸的PCR技术对168例广西壮族人群EBI3 rs6613 A/T和EBI3 rs4905A/G进行多态性检测,对比国际人类基因组计划(Hap Map)公布的中国北京人、日本人、非洲人和意大利人的SNP分型数据,分析5个人群rs6613 A/T、rs4905A/G位点的基因型和等位基因频率差异。结果:在广西壮族人群中,EBI3基因rs6613 A/T位点AT基因型最常见,约为49.4%;T等位基因频率最高,约为52.1%;rs4905A/G多态性位点AC基因型最常见,约为48.2%;C等位基因频率最高,约为50.9%。EBI3基因型及等位基因频率分布于性别无显著相关性(P0.05)。广西壮族人群EBI3基因rs6613A/T位点基因型和等位基因频率与北京人差异无统计学意义(P0.05),但与非洲人、日本人、意大利人差异具有统计学意义(P0.05);EB-13基因rs4905A/G位点基因型和等位基因频率与北京人和日本人差异无统计学意义(P0.05),但与非洲人和意大利人比较差异具有统计学意义(P0.01)。结论:EBI3基因rs6613 A/T和EB-13 rs4905A/G多态性位点基因型和等位基因在广西壮族人群中的分布频率与其他种族和地区人群相比存在差异,这种差异可能是导致某些疾病在不同人群发病率和临床表现存在差异的原因之一。     

Alterations of Choroidal Blood Flow Regulation in Young Healthy Subjects with Complement Factor H Polymorphism

A common polymorphism in the complement factor H gene (rs1061170, Y402H) is associated with a high risk of age-related macular degeneration (AMD). In the present study we hypothesized that healthy young subjects homozygous for the high-risk haplotype (CC) show abnormal choroidal blood flow (ChBF) regulation decades before potentially developing the disease. A total of 100 healthy young subjects were included in the present study, of which 4 subjects were excluded due to problems with genotyping or blood flow measurements. ChBF was measured continuously using laser Doppler flowmetry while the subjects performed isometric exercise (squatting) for 6 minutes. The increase in ChBF was less pronounced than the response in ocular perfusion pressure (OPP), indicating for some degree of choroidal blood flow regulation. Eighteen subjects were homozygous for C, 47 subjects were homozygous for T and 31 subjects were heterozygous (CT). The increase in OPP during isometric exercise was not different between groups. By contrast the increase in ChBF was more pronounced in subjects homozygous for the high risk C allele (p = 0.041). This was also evident from the pressure/flow relationship, where the increase in ChBF in homozygous C carriers started at lower OPPs as compared to the other groups. Our data indicate that the regulation of ChBF is abnormal in rs1061170 CC carriers. So far this polymorphism has been linked to age related macular degeneration (AMD) mainly via inflammatory pathways associated with the complement system dysfunction. Our results indicate that it could also be related to vascular factors that have been implicated in AMD pathogenesis.     

Acyl coenzyme A synthetase long-chain 1 (ACSL1) gene polymorphism (rs6552828) and elite endurance athletic status: a replication study

The aim of this study was to determine the association between the rs6552828 polymorphism in acyl coenzyme A synthetase (ACSL1) and elite endurance athletic status. We studied 82 Caucasian (Spanish) World/Olympic-class endurance male athletes, and a group of sex and ethnically matched healthy young adults (controls, n=197). The analyses were replicated in a cohort of a different ethnic origin (Chinese of the Han ethnic group), composed of elite endurance athletes (runners) [cases, n=241 (128 male)] and healthy sedentary adults [controls, n=504 (267 male)]. In the Spanish cohort, genotype (P=0.591) and minor allele (A) frequencies were similar in cases and controls (P=0.978). In the Chinese cohort, genotype (P=0.973) and minor allele (G) frequencies were comparable in female endurance athletes and sedentary controls (P=0.881), whereas in males the frequency of the G allele was higher in endurance athletes (0.40) compared with their controls (0.32, P=0.040). The odds ratio (95%CI) for an elite endurance Chinese athlete to carry the G allele compared with ethnically matched controls was 1.381 (1.015-1.880) (P-value=0.04). Our findings suggest that the ACSL1 gene polymorphism rs6552828 is not associated with elite endurance athletic status in Caucasians, yet a marginal association seems to exist for the Chinese (Han) male population.     

The association of rs1149048 polymorphism in Matrilin-1(MATN1) gene with adolescent idiopathic scoliosis susceptibility: a meta-analysis

Several previous studies have evaluated the association between rs1149048 polymorphism in the matrilin-1 gene (MATN1) and the risk of adolescent idiopathic scoliosis (AIS). However the results of those studies were inconsistent. We conducted this meta-analysis to assess whether rs1149048 polymorphism was involved in the risk of AIS and evaluated the associations in different ethnicities. Electronic databases, such as: PubMed, EMBASE, WANFANG databases in any languages up to Dec 2012 were searched to assess the association between rs1149048 polymorphism and AIS. Meta-analysis was performed by STATA 12.0 software to estimate the pooled odds ratio (OR) and the 95 % confidence interval (CI). Finally four papers including five studies which involved 1436 AIS patients and 1,879 controls were identified for this meta-analysis. The results showed that G allele of the rs1149048 was significantly associated with increased AIS risk [OR = 1.13, 95 % CI (1.02–1.25), P = 0.023]. As for genotype (GG vs. GA + AA), homozygous GG genotype was also found to be a risk factor of developing AIS. The subgroup meta-analysis results showed G allele and GG genotype were significantly associated with AIS in Asian group but not in Caucasian group. Neither Egger’s test nor Begg’s test found evidence of publication bias in current study (P > 0.05). In summary, this meta-analysis found an overall significant association of rs1149048 polymorphism with risk of AIS, especially in Asian population. The relationship between rs1149048 polymorphism and AIS in other ethnic population is needed to be investigated.     

A novel polymorphism of human complement component C3 detected by means of a monoclonal antibody

A mouse monoclonal antibody, HAV 4-1, obtained after immunization of a BALB/c mouse with purified C3F, detected a novel genetic polymorphism of human complement component C3 in a simple immunoblotting system. The frequency of HAV 4-1-positive genes was 20.1%. Reactivity of HAV 4-1 was closely related to C3F, but certain individuals with the C3F allele did not react with HAV 4-1. Conversely, certain C3S homozygous individuals did react with HAV 4-1. The polymorphism detected by this monoclonal antibody is therefore different from the previously described polymorphism based on charge differences.     

The frequency and distribution of thiopurine S-methyltransferase alleles in south Iranian population

Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Variability in TPMT activity is mainly due to genetic polymorphism. The frequency of the four allelic variants of the TPMT gene, TPMT*2 (G238C), TPMT*3A (G460A and A719G), TPMT*3B (G460A) and TPMT*3C (A719G) were determined in an Iranian population from south of Iran (n = 500), using polymerase chain reaction (PCR)-RFLP and allele-specific PCR-based assays. Four hundred seventy four persons (94.8%) were homozygous for the wild type allele (TPMT*1/*1) and twenty five people were TPMT*1/*3C (5%). One patient was found to be heterozygous in terms TPMT*1 and *2 alleles with genotype of TPMT*1/*2 (0.2%). None of the participants had both defective alleles. The TPMT*3C and *2 were the only variant alleles observed in this population. The total frequency of variant alleles was 2.6% and the wild type allele frequency was 97.4%. The TPMT*3B and *3A alleles were not detected. Distributions of TPMT genotype and allele frequency in Iranian populations are different from the genetic profile found among Caucasian or Asian populations. Our findings also revealed inter-ethnic differences in TPMT frequencies between different parts of Iran. This view may help clinicians to choose an appropriate strategy for thiopurine drugs and reduce adverse drug reactions such as bone marrow suppression.     

Different Allelic Distribution of a Single SNP Between Sexes in Humans

We searched for a difference in allele distribution between males and females of a single nucleotide polymorphism located in the human beta T-cell receptor, in 500 subjects (200 males and 300 females). Genotype analysis gave the following results: among the males, 114 (57%) were heterozygous for the T/C polymorphism, 52 (26%) were homozygous (T/T), and 34 (17%) were homozygous (C/C). Among the females, 142 (47.3%) were heterozygous, 73 (24.3%) were homozygous (T/T), and 85 (28.3%) were homozygous (C/C). The allele frequency was significantly different between sexes (chi2 = 8.799, P = 0.012).     

CISH基因多态性与结核病易感性的相关性研究

目的:寻找肺结核的易感位点,探索宿主遗传因素差异对肺结核发病的影响,为肺结核的预防和药物研发提供理论依据。方法:对1218名汉族居民进行病例对照研究,其中病例组600例,对照组618例,进行流行病学调查和生化指标检查。运用限制性片段长度多态性聚合酶链反应(PCR-RFLP)技术检测CISH基因rs2239751和rs622502的基因型分布,探讨CISH基因多态性与中国汉族人群肺结核易感性的关联性。结果:CISH基因的rs2239751和rs622502等位基因分布均符合Hardy-Weinberg(H-W)遗传平衡定律(P0.05)。rs2239751位点基因型和等位基因分布在两组间差异有统计学意义,P值分别为0.013和0.01,并且携带C等位基因个体患肺结核的风险是携带A等位基因的个体1.16倍(95%CI=1.03-1.29,P=0.01)。rs2239751基因分型结果在女性病例组和对照组中差异有统计学意义,P值为0.007,OR(95%CI)为1.51(1.12-2.03)。rs2239751基因分型结果在45岁人群病例组和对照组中差异有统计学意义,P值为0.010,OR(95%CI)为1.32(1.07-1.64)。rs622502位点基因型和等位基因分布在两组间差异均无统计学意义(P0.05)。结论:在汉族人群中,rs2239751位点多态性可能是肺结核的危险因素之一,C等位基因为风险等位基因。rs2239751基因多态性与肺结核的关联性仅限于于女性和45岁人群。rs622502位点多态性可能与肺结核无关。     

Interleukin 4 receptor is associated with an increase in body mass index in Koreans

A body of evidence indicates obesity is an inflammatory state with chronic activation of the immune system. The interleukin 4 receptor (IL4R) single nucleotide polymorphism (SNP), rs 180275 (1902A>G) is well recognized for its association with atopy and other inflammatory diseases. We assessed the possible association of rs 180275 and rs 1805010 with obesity in Korean population. Study subject consisting of 876 Koreans were divided into three groups: subjects with 1) BMI<25, 2) BMI between 25 and 27, and 3) BMI>27. Analyses of genotype distributions and allele frequencies of study subjects revealed that rs 180275 polymorphism was associated with an increase in BMI in Korean population (P=0.009 and 0.011, respectively) while no association was found between rs 1805010 and obesity. We observed significantly lower percentage of rs 180275 G allele in subjects with BMI>27 than in subjects with BMI< or =27 (9.9% vs. 16.0%). Logistic regression analysis revealed that the odds ratio (OR) for an increase in BMI associated with the G vs. A allele was 0.57 [95% Confidence interval (CI)=0.39-0.85, p=0.002], which strongly implicates the protective role of rs 180275 G allele against an increase in BMI. Haplotype analysis revealed no association was present between rs 180275 and rs 1805010 polymorphisms. The frequency of rs 180275 G allele is significantly lower in subjects with BMI>27, suggesting the protective role of IL4R rs 180275 G allele against an increase in BMI in Korean population.     

Polymorphism in the Retinoic Acid Metabolizing Enzyme CYP26B1 and the Development of Crohn’s Disease

Several studies suggest that Vitamin A may be involved in the pathogenesis of inflammatory bowel disease (IBD), but the mechanism is still unknown. Cytochrome P450 26 B1 (CYP26B1) is involved in the degradation of retinoic acid and the polymorphism rs2241057 has an elevated catabolic function of retinoic acid, why we hypothesized that the rs2241057 polymorphism may affect the risk of Crohn’s disease (CD) and Ulcerative Colitis (UC). DNA from 1378 IBD patients, divided into 871 patients with CD and 507 with UC, and 1205 healthy controls collected at Örebro University Hospital and Karolinska University Hospital were analyzed for the CYP26B1 rs2241057 polymorphism with TaqMan® SNP Genotyping Assay followed by allelic discrimination analysis. A higher frequency of patients homozygous for the major (T) allele was associated with CD but not UC compared to the frequency found in healthy controls. A significant association between the major allele and non-stricturing, non-penetrating phenotype was evident for CD. However, the observed associations reached borderline significance only, after correcting for multiple testing. We suggest that homozygous carriers of the major (T) allele, relative to homozygous carriers of the minor (C) allele, of the CYP26B1 polymorphism rs2241057 may have an increased risk for the development of CD, which possibly may be due to elevated levels of retinoic acid. Our data may support the role of Vitamin A in the pathophysiology of CD, but the exact mechanisms remain to be elucidated.     

Heterogeneity of apolipoprotein E polymorphism in different Mexican populations

Mexico has approximately 100 million inhabitants. Most of the urban Mexican population has been considered mestizo (Indian and Spanish descent), whereas the Indian population predominates in rural areas and small towns in the countryside. In this study we analyzed the apolipoprotein E (APOE) polymorphism in Guadalajara (the second largest metropolitan area of Mexico) and its surrounding areas, two adjoining states (Nayarit and Durango), and an Indian town (Huichol Indians) from western Mexico. APOE*3 was the most common allele, and APOE*3/*3 was the most common genotype in all populations studied. Guadalajara revealed the highest frequency of the APOE*2 allele (7.8%); the frequency decreased in the rural area (4.4%), followed by Nayarit (1.6%), and was absent in Durango and in the Huichols. On the contrary, the lowest frequency of the APOE*4 allele was in Guadalajara (8.4%); the frequency increased in the rural area (9.3%), in Nayarit and Durango (11.5% and 11.7%), and reached a high frequency in the Huichol Indians (28%). The distribution of the APOE allele in the western population of Mexico is similar to those described in Mexican American migrants living in the United States but is different from those populations living in Mexico City. This study shows the heterogeneity of the Mexican population, where the frequency of the APOE*2 allele is higher in Guadalajara than in other urban areas of Mexico and is similar to frequencies described in the Caucasian population. On the contrary, the Huichols revealed the highest frequency of the APOE*4 allele in Mexico and in the Americas. This information could be useful for the study of dyslipidemias associated with chronic diseases and as markers of ethnic variation in the Americas.     

Variation in NOD2 augments Th2- and Th17 responses to myelin basic protein in multiple sclerosis

Variations in the gene for the nucleotide-binding oligomerisation domain (NOD) 2 have been associated with Crohn's disease but not multiple sclerosis (MS). Here we investigate the effect of three polymorphisms in the NOD2 gene (rs5743277, rs2066842 and rs5743291) on cytokine production and CD4+ T cell proliferation elicited by human myelin basic protein (MBP) in blood mononuclear cell (MNC) cultures from 29 patients with MS. No polymorphism was observed at rs5743277. No associations with the rs2066842 polymorphism were found. Concerning rs5743291, none were homozygous for the minor allele. Seven of 29 (24%) patients were heterozygous, and five of these (71%) exhibited increased MBP-induced CD4+ T cell proliferation versus four of 22 (18%), who were homozygous for the major allele (p<0.04). Interleukin (IL)-5 was induced by MBP in MNC from the same five carriers versus two (9%) homozygotes (p<0.004); four carriers (57%) versus three non-carriers (14%) exhibited IL-17 responses to MBP (p<0.04). By contrast, we found no association between the polymorphisms investigated and interferon-gamma-, tumor necrosis factor-alpha-, IL-2, -4- or IL-10 responses to MBP. These results indicate that the rs5743291 polymorphism influences T helper (Th) cell 2- and Th17 cell responses in MNC from MS patients.     

Association of polymorphisms in glutathione-S-Transferase and DNA repair genes with ovarian cancer risk in the Russian population

Polymorphism of glutathione-S-transferase (GSTA1, GSTM1, GSTM3, GSTP1, and GSTT1) and DNA repair (ERCC1, ERCC2, and XRCC1) genes in samples of ovarian cancer patients and healthy women of the Russian ethnic group was studied. A trend in the allele frequency variation of ERCC2 gene single nucleotide polymorphism (rs13181, A > C) was revealed. The A allele frequency was higher in the sample of patients (60,6% versus 52,9%, P = 0.058).     

与宁夏人群强直性脊柱炎关联的新基因淋巴毒素-α(LTA)的识别

淋巴毒素-α(Lymphotoxin-alpha,LTA)基因与系统性红斑狼疮、银屑病及类风湿性关节炎的遗传性有关,但目前还未有关于LTA基因与强直性脊柱炎(Ankylosing spondylitis,AS)关联的报道。文章采用病例-对照设计,在宁夏人群中对人类白细胞抗原(Human leukocyte antigen,HLA)的Ⅲ类基因约58 kb区域进行了高密度标志的基因组扫描,在33个SNPs及其单倍型中,仅定位于LTA基因中的SNPs组成的TCC单倍型的分布在病例-对照间比较有统计学意义(P=0.0005)。在宁夏群体(病例组:300,对照组:385)中发现,LTA基因中的rs909253 T/C多态性在AS患者中出现的频率显著高于正常对照(28.5%vs 19.7%,P=2×10-6)。结果表明LTA基因变异和AS易感性之间存在相关性,由此识别LTA基因可能与宁夏人群AS关联。     

LIPG promoter polymorphism is associated with ischemic stroke in Korean population

Endothelial lipase (LIPG) is a member of the triglyceride lipase family which includes hepatic lipase and lipoprotein lipase. Its activity is related to clinically important parameters like blood lipid levels, hypertension, and obesity. In this work, we investigated the association of a LIPG promoter polymorphism, rs9958947C>T, with susceptibility to ischemic stroke in a Korean population. A total of 1,144 subjects (656 cerebral infarction patients and 488 controls) were enrolled on a voluntary basis. The rs9958947C>T polymorphism was genotyped using the single-base extension method. The association of rs9958947C>T with disease status was evaluated by statistical analyses. The frequencies of the rs9958947 C and T alleles were significantly different between the stroke patient group and control group (OR [95% CI], 1.300 [1.000?C1.691], P=0.0449). A significantly higher frequency of the CT+TT genotype was observed in the patient group compared to the control group (CC/CT+TT, OR [95% CI], 1.632 [1.094?C2.435], P=0.0164). The results suggest that the T allele of the LIPG promoter polymorphism rs9958947C>T should be considered as a genetic risk factor for ischemic stroke. Further association studies in other ethnic populations would help to generalize this hypothesis.