Genetic variation in soluble epoxide hydrolase (EPHX2) is associated with forearm vasodilator responses in humans

Cytochrome P450-derived epoxyeicosatrienoic acids are potent vasodilators in preclinical models and are hydrolyzed by soluble epoxide hydrolase (EPHX2). Associations between the EPHX2 Lys55Arg and Arg287Gln polymorphisms and cardiovascular disease risk have been reported; however, their impact on vascular function in humans has not been investigated. In 265 volunteers (198 white, 67 black American), forearm blood flow was measured by strain-gauge venous occlusion plethysmography at baseline and in response to bradykinin, methacholine, and sodium nitroprusside. Forearm vascular resistance was calculated as mean arterial pressure/forearm blood flow. In white Americans, Lys55Arg genotype was associated with vasodilator response to bradykinin, such that forearm blood flow was significantly lower (P = 0.043) and forearm vascular resistance was significantly higher (P = 0.013) in Arg55 variant allele carriers compared to wild-type individuals. Significant associations were also observed with methacholine and sodium nitroprusside. In contrast, no relationship was observed in black Americans. In black Americans, Arg287Gln genotype was associated with vasodilator response to bradykinin. Although the difference in forearm blood flow did not reach statistical significance (P = 0.058), forearm vascular resistance was significantly lower (P = 0.037) in Gln287 variant allele carriers compared to wild-type individuals. Significant associations were also observed with methacholine and sodium nitroprusside. In white Americans, Gln287 variant allele carriers did not exhibit significantly higher forearm blood flow (P = 0.128) or lower forearm vascular resistance (P = 0.080). Genetic variation in EPHX2 is associated with forearm vasodilator responses in a bradykinin receptor- and endothelium-independent manner, suggesting an important role for soluble epoxide hydrolase in the regulation of vascular function in humans.

A randomised controlled trial of cognitive behaviour therapy and motivational interviewing for people with Type 1 diabetes mellitus with persistent sub-optimal glycaemic control: a Diabetes and Psychological Therapies (ADaPT) study

OBJECTIVES

To determine whether (i) motivational enhancement therapy (MET) + cognitive behaviour therapy (CBT) compared with usual care, (ii) MET compared with usual care, (iii) or MET + CBT compared with MET was more effective in improving glycaemic control when delivered by general nurses with additional training in these techniques.

DESIGN

A three-arm parallel randomised controlled trial as the gold standard design to test the effectiveness of psychological treatments.

SETTING

The recruiting centres were diabetes clinics in seven acute trusts in south-east London and Greater Manchester.

PARTICIPANTS

Adults (18-65 years) with a confirmed diagnosis of type 1 diabetes for a minimum duration of 2 years and a current glycated (or glycosylated) haemoglobin (HbA1c) value between 8.2% and 15.0%.

INTERVENTIONS

The control arm consisted of usual diabetes care which varied between the hospitals, but constituted at least three monthly appointments to diabetes clinic. The two treatments arms consisted of usual care with MET and usual care with MET + CBT.

MAIN OUTCOME MEASURES

The primary outcome was HbA1c at 12 months from randomisation. Secondary outcome measures were 1-year costs measured by the Client Service Receipt Inventory at baseline, 6 months and 12 months; quality of life-years [quality-adjusted life-years (QALYs)] measured by the SF-36 (Short Form-36 Health Survey Questionnaire) and EQ-5D (European Quality of Life-5 Dimensions) at baseline and 12 months.

RESULTS

One thousand six hundred and fifty-nine people with type 1 diabetes were screened and 344 were randomised to MET + CBT (n = 106), MET (n = 117) and to usual care (n = 121). The 12-month follow-up rate for HbA1c was 88% (n = 305). The adjusted mean 12-month HbA1c was 0.45% lower in those treated with MET + CBT [95% confidence interval (CI) 0.16% to 0.79%, p = 0.008] than for usual care; 0.16% lower in those treated with MET (95% CI 0.20% to 0.51%, p = 0.38) than for usual care; and 0.30% lower with MET + CBT than with MET (95% CI -0.07% to 0.66%, p = 0.11). The higher the HbA1c, and the younger the participant at baseline, the greater was the reduction in HbA1c. The interventions had no effect on secondary outcomes such as depression and quality of life. The economic evaluation was inconclusive. Both interventions were associated with increased health care costs than for usual care alone. There was no significant difference in social costs. Cost effectiveness ratios, up to one year, varied considerably according to whether QALY estimates were based on EQ-5D or SF-36 and whether imputed or complete data were used in the analyses.

CONCLUSIONS

A combination of MET and CBT may be useful for patients with persistent sub-optimal diabetic control. MET alone appears less effective than usual care. Economic evaluation was inconclusive.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN77044517.

Consanguinity mapping of congenital heart disease in a South Indian population

BACKGROUND

Parental consanguinity is a risk factor for congenital heart disease (CHD) worldwide, suggesting that a recessive inheritance model may contribute substantially to CHD. In Bangalore, India, uncle-niece and first cousin marriages are common, presenting the opportunity for an international study involving consanguinity mapping of structural CHD. We sought to explore the recessive model of CHD by conducting a genome-wide linkage analysis utilizing high-density oligonucleotide microarrays and enrolling 83 CHD probands born to unaffected consanguineous parents.

METHODOLOGY/PRINCIPAL FINDINGS

In this linkage scan involving single nucleotide polymorphism (SNP) markers, the threshold for genome-wide statistical significance was set at the standard log-of-odds (LOD) score threshold of 3.3, corresponding to 1995ratio1 odds in favor of linkage. We identified a maximal single-point LOD score of 3.76 (5754ratio1 odds) implicating linkage of CHD with the major allele (G) of rs1055061 on chromosome 14 in the HOMEZ gene, a ubiquitously expressed transcription factor containing leucine zipper as well as zinc finger motifs. Re-sequencing of HOMEZ exons did not reveal causative mutations in Indian probands. In addition, genotyping of the linked allele (G) in 325 U.S. CHD cases revealed neither genotypic nor allele frequency differences in varied CHD cases compared to 605 non-CHD controls.

CONCLUSIONS/SIGNIFICANCE

Despite the statistical power of the consanguinity mapping approach, no single gene of major effect could be convincingly identified in a clinically heterogeneous sample of Indian CHD cases born to consanguineous parents. However, we are unable to exclude the possibility that noncoding regions of HOMEZ may harbor recessive mutations leading to CHD in the Indian population. Further research involving large multinational cohorts of patients with specific subtypes of CHD is needed to attempt replication of the observed linkage peak on chromosome 14. In addition, we anticipate that a targeted re-sequencing approach may complement linkage analysis in future studies of recessive mutation detection in CHD.

External Quality Assurance Schemes: The Impact of Participation in the UK Versus Rest of the World: 5 Year Data from the UK National External Quality Assurance Scheme

The American Society of Clinical Oncology/College of American Pathologists guidelines highlighted the critical importance of quality assurance in diagnostic testing for HER2.Unstained formalin-fixed, paraffin-embedded human breast carcinoma cell line sections were circulated to scheme participants on 15 occasions over 5 years. “Reference laboratories” reported results for the HER2/chromosome 17 ratio and HER2 copy number for 5 years for each cell line. Results from the 5th years participants (3 runs 13, 14, 15) were assessed for the pass rate in UK versus rest of the world (EU, US, Asia, etc). The number of participants was 76-78 laboratories/run (UK 30-35, ROW 43-46).Results: The percentage of laboratories achieving “appropriate” results ranged from 78-82% overall. Significantly higher performance was observed over 3 runs for UK laboratories (91-97%, “appropriate” results) versus ROW laboratories (67-74% “appropriate” results), p = 0.004. All methods used by scheme participants in UK Laboratories had excellent performance rates (Pathvysion, PharmDx, Ventana SISH/Inform, Kreatech Posieden). However in the ROW there was evidence of poor performance, which may be related to the assay format, although numbers of comparisons are relatively small.Participation in external quality assurance schemes is a valuable mechanism for evaluation and benchmarking of performance between laboratories. It also serves to improve consistency of HER2 testing by in situ hybridization. Using data from the UK NEQAS scheme we identified that laboratories whose performance is monitored and linked to an intergrated corrective action component(UK laboratories) perform consistently better than laboratories where performance data alone is provided (ROW). In the UK both participation and adequate performance in a national EQA scheme is required for laboratory accreditation. Whilst, in the context of robust EQA there is no evidence that different methods affect performance, in the ROW implementation of some assays appears sub-optimal. This poor performance does not, however, identify fundamental flaws with these methods, which are currently very well controlled amongst UK users but suggests greater attention to EQA results and change to improve laboratory performance is required in the rest of the world.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6010.

An Investigation into a Panel of Isogenic Taxane Resistant Breast Cancer Cell Lines Using Transcriptomic and Genomic Methods

Background: Taxanes are a powerful chemotherapeutics used to treat breast cancer. Taxane resistance has become increasingly more prevalent in the clinic; This problem is exacerbated by a lack of understanding of mechanisms underlying taxane resistance.Materials and Methods: 3 isogenic breast cancer cell-line panels: paclitaxel resistant (PACR) MDA-MB-231s/ZR75-1s and docetaxel resistant (DOCR) ZR75-1s were derived by culturing cells in incrementally escalating doses of taxanes over time. MDA-MB-231: native, 5nM, 25nM and 100nM PACR cells, ZR75-1: native, and 5nM, 25nM, and 50nM PACR and ZR75-1: native, and 5nM, 25nM and 50nM DOCR cells were analysed. RNA from native and PACR MDA-MB-231 cell lines was analysed on the Illumina® human ref.8V2 chip. Data were analysed using IlluminaGui. For aCGH, DNA was extracted from MDA-MB-231 PACR, ZR75-1 PACR and DOCR and respective parental lines, labelled and hybridised to a tiling path BAC microarray (resolution ∼50kb). Each cell-line was tested against reference samples of DNA from pooled female blood. Taxane resistant cells were tested against their parental cell line.Results: Illumina data demonstrated that resistance to increasing doses of paclitaxel is associated with sequential increases in mRNA dysregulation in MDA-MB-231 cells.A number of comparisons between the illumina data of native and the PACR cells were made using a p value of P≤0.001. The first comparison made using the illumina data, was between the 5nM PACR cells and the native cell lines: 25 significantly up or downregulated genes were identified. When the 25nM PACR cells were compared to the native cell lines, 225 genes were found to be significantly up or downregulated. Finally, when 100nM PACR cells were compared to native cells, 425 genes were found to be significantly up or downregulated. A group of genes identified that were common to multiple paclitaxel resistant groups included candidates such as YY1, AURKA and CCND2. aCGH has identified significant differences in patterns of copy number loss, gain and amplification in the taxane resistant cell lines, including chromosome loss of 6p and gain of 2p. Illumina and aCGH data were overlaid using specially designed algorithms.Discussion: Both aCGH and expression arrays highlight a progressive acquisition of molecular and transcriptomic alterations in isogenic breast cancer cell lines resistant to increasing doses of taxanes. Further mapping of transcriptomic and genomic profiles will enable identification of key molecular targets for restoration of taxane sensitivity. Genes upregulated in taxane resistant clones identified in the illumina experiment, in particular those whose upregulation is underpinned by DNA copy number gains in resistant cells, may represent genes which may be targeted with inhibitors to test potential candidates for reversing taxane resistance.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1134.

Expression Levels of Co-Regulators in Early Breast Cancer

Introduction: The p160 (SRC) family of estrogen receptor (ER) co-activators have important implications in tamoxifen resistance. The SRC family play a central role in ER mediated transcription. There are three family members; SRC-1, SRC-2 and AIB1. AIB1 is amplified in 5-10% of human breast cancers. SRC-1 expression is associated with HER2 expression, increased risk of recurrence and insensitivity to endocrine treatment. Co-factors interact with the ER and basal transcriptional machine to activate or repress ER-mediated transcription. To investigate the role of ER and its co-factors in breast cancer we have carried out quantitative RT-PCR (qRT-PCR) to measure the relative expression of ERa and its co-factors.Methods: In this study we examined patients which were untreated or treated with chemotherapy or hormonal therapy following breast conservation surgery. RNA was extracted from 340 early breast cancer specimens from the Edinburgh Breast Conserving Surgery cohort (BCS). The BCS is a fully documented consectutive cohort of breast cancers treated by conservation surgery, axillary node sampling or clearance, and whole breast radiotherapy between 1981-1998. Clinico-pathological features and complete follow up (duration >10 years) is available for this cohort. qRT-PCR was carried out using primers for ER, SRC-1, SRC-2, AIB1, NCoR1 and SMRT.Results: This study demonstrated SRC-1 expression to be negatively correlated with both SRC-2 and AIB1 expression. SRC-1 expression was also negatively correlated with the co-repressors NCoR1 and SMRT expression. There was a strong correlation between the co-repressors, NCoR1 and SMRT and the co-activators SRC-2 and AIB1. Relapse-free survival (RFS) was estimated using Kaplan-Meier curves. Patients who had high expression of all three co-activators had reduced relapse-free survival (HR: 2.15 95%C.I. 1.175-3.921, p=0.01). No significant association was noted with overall survival. Exploratory subgroup analysis was under powered and showed no significant association with outcome.Conclusion: In conclusion, our study of expression levels of ER and its cofactors by quantitative RT-PCR in breast cancer samples revealed a correlation between the co-factors and co-repressors. These findings would suggest that ER and cofactors may play a synergistic role in the development and progression of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2127.

Duplication of Chromosome 17 CEP Predicts for Anthracycline Benefit: A Meta-Analysis of 4 Trials

ABSTRACT WITHDRAWN: This abstract was withdrawn by the authors prior to the start of the Symposium.

Background: Current evidence for HER2/TOP2A as predictive biomarkers of anthracycline response is conflicting. An interim meta-analysis (Di Leo et al Cancer Res;69:99S SABCS2009) suggested a weak, statistically significant, association between TOP2A and anthracycline benefit. We previously showed duplication of chromosome 17 alpha satellite (CEP17) predicted sensitivity to anthracyclines independently in three trials (BR9601, NEAT and MA.5, Bartlett et al Cancer Res 69:74S/364S). We performed a retrospective meta-analysis, incorporating data from 4 trials (including the Belgium study), to test the hypothesis that CEP17 is a predictive biomarker for anthracycline benefit in order to provide a unifying hypothesis in trials for which previous biomarker data is conflicting.Methods: FISH was performed in 2 labs (Bartlett lab for BR9601/NEAT & Belgian studies & O'Malley lab for MA5). ER/PgR (IHC) etc were collected from trial Case Report Forms. BR9601/NEAT and Belgian study tumors were scored counting all cells with a minimum of one CEP17 signal/cell: in MA.5 a minimum of 2 CEP17 signals were required for cells to be scored. These methodological differences did not affect HER2/CEP17 ratios but necessitated different definitions for CEP17 duplication defined as >1.86 observed copies/cell for BR9601, NEAT and JB (Watters BCRT 2003 77:109-14) and >2.25 for MA.5 (Goetz 2004).Results: FISH was successful in 85% (2531/2975) of cases. CEP17 duplication was detected in 27.5% of tumors (BR9601=37.6%, NEAT=20.0%, MA5=40.2% & JB=28.5%) and was associated with poorer RFS & OS (HR 0.80 95%CI 0.7-0.92 p=0.011 & HR 0.79, 95%CI 0.68-9.92, p=0.018, respectively).A significant treatment*marker interaction was observed in a meta-analysis of all data (2531 cases) as univariate(p<0.005) & multivariate adjusted for treatment, grade, size, ER, nodes CEP17, CEP17*treatment & HER2 and for recurrence free (HR 1.67 95%CI 1.25-2.22, p=0.0006) & overall (1.63 95%CI 1.18-2.25, p=0.003) survival. In the two largest studies, NEAT (n=1462) and MA5 (n=622), this treatment*marker interaction (CEP17) was significant for RFS (p<0.05) in all other analyses non-significant trends for RFS & OS were seen. (Trial specific HRs with 95%CIs RFS: 1.37 (0.56-3.15), 1.77 (1.07-2.90), 1.62 (1.02-2.58) & 1.69 (0.43-6.68), OS: 1.35 (0.54-3.38), 1.64 (0.96-2.80), 1.67 (0.99-2.84) & 2.05 (0.43-9.69); BR9601, NEAT, MA5 & Belgian respectively) analyses.Conclusions: Combined meta-analysis of 4 adjuvant trials demonstrated a highly significant treatment by marker effect for CEP17 duplication as a predictor of benefit from anthracyclines for both RFS in both univariate and multivariate regression analyses. HER2 (all 4 trials) and TOP2A (NEAT/BR9601) did not show any significant interactions. CEP17 duplication may reflect either chromosomal instability or polyploidy and further analysis is warranted to explore the underlying mechanisms for this effect. CEP17 is readily assessed in ISH analysis of HER2 status and may represent a clinically useful biomarker for selection of patients likely to benefit from anthracycline containing chemotherapies.

The Expression of Insulin-Like Growth Factor-1 Receptor (IGF-1R) in Early Breast Cancer

Background: The insulin-like growth factor-1 receptor (IGF-1R) is expressed in normal breast epithelial cells and breast carcinomas. A number of studies have examined the over-expression of IGF-1R in breast cancer with the range of between 39% to 93%. However, many of these studies were carried out using ELISAs, radioimmunoassay with small patient cohorts. Phosphorylation of IGF-1R results in the activation of the MAPK and PI3K/Akt pathway. Activation of the PI3K/Akt pathway under the influence of IGF-1R plays an important role in maintaining the proliferation of breast cancer cells that are resistant to gefitnib, trastuzumab or chemoradiotherapy in vitro and in vivo. In the present study, we examined the expression of IGF-1R in early breast cancer and investigated the clinicopathological implications using immunohistochemistry and FISH.Methods: TMAs from a consecutive series (1981-98) of 1,812 women managed by wide local excision and postoperative radiotherapy (45Gy in 20-25 fractions) were collected following appropriate ethical review. Of 1686 cases stained, 198 received no adjuvant hormonal or chemotherapy, 1106 received tamoxifen only as adjuvant therapy and 144 received a combination of hormonal and chemotherapy. Median age at diagnosis was 56, 72% were post-menopausal, 23.9% node positive, median size was 1.5 cm. Samples were stained, using triplicate 0.6mm2 TMA cores for IGF-1R.Results: FISH for IGF1R gene amplification was successful in 343/408 cases (84%). Only 7 cases of IGF1R amplification were observed (2%). IGF1R expression was successfully evaluated in 1597 of 1686 (94.7%) cases. High levels of IGF-1R expression was weakly associated with tumour ER-a (correlation coefficient, 0.108; p=2.2 x 10-5) and PgR levels (correlation coefficient 0.162; p=1.86x10-10) and inversely correlated with EGFR expression (correlation coefficient -0.189; p=6.33x10-6). No association was noted between IGF1R expression and other molecular or clinical markers, such as tumour size. There was a trend for over-expression of IGF-1R to link with increased distant relapse free survival, particularly in ER positive breast cancers. This trend is time dependent, such that no difference in outcome is observed at 15 years.Conclusions: We have demonstrated in a large cohort of patients that IGF-1R gene amplification is a rare event, and over-expression is weakly associated with good prognostic features (ERa and PgR, lack of EGFR and better outcome).

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2128.

The TEAM Trial Pathology Study Identifies Potential Prognostic and Predictive Biomarker Models for Postmenopausal Patients Treated with Endocrine Therapy

Background: The Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial included prospectively planned biomarker studies to identify prognostic and predictive biomarkers for patients receiving endocrine therapy. Quantitative IHC data for ER/PgR (Can Res 69:83S, SABCS2008), HER2, HER3 and Ki67 was available for the current analysis relative to outcome of estrogen receptor–positive (ER+) early postmenopausal breast cancer (BC) patients treated with exemestane versus tamoxifen.Patients & Methods: Pathology blocks from 4598 TEAM patients were collected and tissue microarrays constructed. Quantitative analysis of hormone receptors (HER2/3) by conventional IHC, and image analysis derived continuous scores for Ki67/ER/PgR were analyzed relative to disease-free survival and treatment on an intent to treat basis using survival data for the first 2.75 years of the TEAM trial. Data on HER2FISH and EGF Receptor IHC will be presented.Results: Of 4595 eligible cases samples received, 16 were excluded, 271 had incomplete biomarker data, leaving 4308 patients for the final biomarker analysis. 1275 (30%) cases were HER2/3 positive.A significant treatment by marker effect was observed for exemestane versus tamoxifen with HER2/3 negative cases deriving benefit from aromatase inhibitor treatment (HER2/3-ve HR=0.69 95%CI, 0.53-0.88; HER2/3 pos HR, 1.13; 95%CI, 0.82–1.55; p=0.016 for interaction in multivariate analysis). By conventional and STEPP analysis no predictive effect of Ki67 was observed. In multivariate regression analysis increased HER2 expression (P=0.0001) decreased PgR expression (P<0.0001) and increased percentage of Ki67 positive cells (P=0.004) as continuous IHC variables were independently prognostic as were size (P=0.0001), nodal status (P<0.0001), grade (P=0.03) and age (P<0.0001).Conclusion: Multiple biological parameters (HER2/PgR/Ki67) are independently prognostic in ER+ve early postmenopausal BC. Modelling will be explored to derive prognostic and potentially predictive biomarker signatures for application in BC. Preferential exemestane versus tamoxifen treatment benefit was seen in HER2/3 negative cases, whilst HER2/3 positive cases had a poor prognosis in this population receiving hormonal therapy (suggesting resistance to endocrine therapy), and no evidence of benefit from AIs versus tamoxifen. Type I receptor tyrosine kinases may identify breast cancers with relative resistance to all forms of endocrine therapy. Whilst Ki67 alone was not predictive of benefit from Ais, Ki67, HER2 and PgR were independent prognostic variables and modelling of predictive/prognostic effects may further inform treatment selection in early postmenopausal breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 75.

Prelminary Results of a NEQAS Ring Study Evaluating the Ventana INFORM™ HER2 Dual Colour Single Slide ISH Assay

Background: Recent innovations in HER2 testing include the development of novel chromogenic in situ hybridisation tests. Most countries use FISH or ISH based testing for HER2 gene amplification in equivocal (IHC 2+) cases. Data on the reproducibility and portability of novel and even established HER2 ISH methods is sparse. We report initial results from the multicentre evaluation of intra and inter-observer/site variation in scoring HER2 results from 30 breast cancers measured in 5 laboratories using the Ventana Dual colour ISH assay.Methods: A commercially available tissue micro-array (TMA; Stretton Scientific UK) containing 2 replicate cores from 30 breast cancers was circulated to 5 UK NEQAS reference laboratories (numbered 1-5). All laboratories performed chromogenic ISH using a 60 core TMA and reported results for all assessable cores. For all cases 20 cells were scored and a further 20 cells scored on a separate occasion to check intra-observer variation. Results were collated centrally and compared with FISH peformed in a single laboratory. Concordance between FISH and CISH is reported on a core by core and case by case analysis. Intra and inter-observer variation between laboratories is also assessed. Finally regression analysis comparing results was performed. Results from a single laboratory are presented here and full results will be available for the meeting.Results: 93% of cores were successfully analysed by the Ventana dual colour ISH assay. 87% of cores were successfully analysed by PathyVision® FISH CISH was concordant with FISH in 96.4% of cores evaluated. In one sample FISH results were 2.05 & 1.93 vs CISH of 2.03 and 2.14. In a second sample FISH results were 1.60 & 1.53 versus CISH results of 2.00 & 1.65. When mean results were calculated (2 cores per case) concordance between FISH and CISH results for this laboratories was 96.7% (1 discordant case – mean FISH – 1.99, mean CISH 2.09). 48 cores were scored twice (20 cells x 2) by a single observer. Mean intra-observer variation (for HER2 ratio) was 1.72% (Range 0.0-7.42%). No difference in scores was observed for the first vs second 20 cells. Scoring 40 cells produced no advantage. For results from a single observer for 2 cores (intra-site variation) from 42 core pairs (each core counted twice) variation was 7.5%.Conclusions: Preliminary evidence from the current study suggest that the Ventana INFORM™ HER2 dual colour single slide ISH assay can be robustly evaluated using conventional scoring approaches (20 cells per case). Concordance with FISH was excellent in the single laboratory reporting results to date. Further evidence will be reported from the other 4 participating laboratories.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6011.

Examination of association to autism of common genetic variationin genes related to dopamine

Autism is a severe neurodevelopmental disorder characterized by a triad of complications. Autistic individuals display significant disturbances in language and reciprocal social interactions, combined with repetitive and stereotypic behaviors. Prevalence studies suggest that autism is more common than originally believed, with recent estimates citing a rate of one in 150. Although multiple genetic linkage and association studies have yielded multiple suggestive genes or chromosomal regions, a specific risk locus has yet to be identified and widely confirmed. Because many etiologies have been suggested for this complex syndrome, we hypothesize that one of the difficulties in identifying autism genes is that multiple genetic variants may be required to significantly increase the risk of developing autism. Thus, we took the alternative approach of examining 14 prominent dopamine pathway candidate genes for detailed study by genotyping 28 single nucleotide polymorphisms. Although we did observe a nominally significant association for rs2239535 (P=0.008) on chromosome 20, single-locus analysis did not reveal any results as significant after correction for multiple comparisons. No significant interaction was identified when Multifactor Dimensionality Reduction was employed to test specifically for multilocus effects. Although genome-wide linkage scans in autism have provided support for linkage to various loci along the dopamine pathway, our study does not provide strong evidence of linkage or association to any specific gene or combination of genes within the pathway. These results demonstrate that common genetic variation within the tested genes located within this pathway at most play a minor to moderate role in overall autism pathogenesis.

Genomic convergence to identify candidate genes for Alzheimer disease on chromosome 10

A broad region of chromosome 10 (chr10) has engendered continued interest in the etiology of late-onset Alzheimer Disease (LOAD) from both linkage and candidate gene studies. However, there is a very extensive heterogeneity on chr10. We converged linkage analysis and gene expression data using the concept of genomic convergence that suggests that genes showing positive results across multiple different data types are more likely to be involved in AD. We identified and examined 28 genes on chr10 for association with AD in a Caucasian case-control dataset of 506 cases and 558 controls with substantial clinical information. The cases were all LOAD (minimum age at onset > or = 60 years). Both single marker and haplotypic associations were tested in the overall dataset and 8 subsets defined by age, gender, ApoE and clinical status. PTPLA showed allelic, genotypic and haplotypic association in the overall dataset. SORCS1 was significant in the overall data sets (p=0.0025) and most significant in the female subset (allelic association p=0.00002, a 3-locus haplotype had p=0.0005). Odds Ratio of SORCS1 in the female subset was 1.7 (p<0.0001). SORCS1 is an interesting candidate gene involved in the Abeta pathway. Therefore, genetic variations in PTPLA and SORCS1 may be associated and have modest effect to the risk of AD by affecting Abeta pathway. The replication of the effect of these genes in different study populations and search for susceptible variants and functional studies of these genes are necessary to get a better understanding of the roles of the genes in Alzheimer disease.

Examination of association of genes in the serotonin system to autism

Autism is characterized as one of the pervasive developmental disorders, a spectrum of often severe behavioral and cognitive disturbances of early development. The high heritability of autism has driven multiple efforts to identify genetic variation that increases autism susceptibility. Numerous studies have suggested that variation in peripheral and central metabolism of serotonin (5-hydroxytryptamine) may play a role in the pathophysiology of autism. We screened 403 autism families for 45 single nucleotide polymorphisms in ten serotonin pathway candidate genes. Although genome-wide linkage scans in autism have provided support for linkage to various loci located within the serotonin pathway, our study does not provide strong evidence for linkage to any specific gene within the pathway. The most significant association (p = 0.0002; p = 0.02 after correcting for multiple comparisons) was found at rs1150220 (HTR3A) located on chromosome 11 ( approximately 113 Mb). To test specifically for multilocus effects, multifactor dimensionality reduction was employed, and a significant two-way interaction (p value = 0.01) was found between rs10830962, near MTNR1B (chromosome11; 92,338,075 bp), and rs1007631, near SLC7A5 (chromosome16; 86,413,596 bp). These data suggest that variation within genes on the serotonin pathway, particularly HTR3A, may have modest effects on autism risk.

Prostate cancer in male BRCA1 and BRCA2 mutation carriers has a more aggressive phenotype

There is a high and rising prevalence of prostate cancer (PRCA) within the male population of the United Kingdom. Although the relative risk of PRCA is higher in male BRCA2 and BRCA1 mutation carriers, the histological characteristics of this malignancy in these groups have not been clearly defined. We present the histopathological findings in the first UK series of BRCA1 and BRCA2 mutation carriers with PRCA. The archived histopathological tissue sections of 20 BRCA1/2 mutation carriers with PRCA were collected from histopathology laboratories in England, Ireland and Scotland. The cases were matched to a control group by age, stage and serum PSA level of PRCA cases diagnosed in the general population. Following histopathological evaluation and re-grading according to current conventional criteria, Gleason scores of PRCA developed by BRCA1/2 mutation carriers were identified to be significantly higher (Gleason scores 8, 9 or 10, P=0.012) than those in the control group. Since BRCA1/2 mutation carrier status is associated with more aggressive disease, it is a prognostic factor for PRCA outcome. Targeting screening to this population may detect disease at an earlier clinical stage which may therefore be beneficial.

Effect of heterogeneity on the chromosome 10 risk in late-onset Alzheimer disease

With the exception of ApoE (APOE), no universally accepted genetic association has been identified with late-onset Alzheimer disease (AD). A broad region of chromosome 10 has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To better examine this region, we combined unbiased genetic linkage with candidate gene association studies. We genotyped 36 SNPs evenly spaced across 80.2 Mb in a family-based data set containing 1,337 discordant sibling pairs in 567 multiplex families to narrow the peak region of linkage using both covariate and subset analyses. Simultaneously, we examined five functional candidate genes (VR22, LRRTM3, PLAU, TNFRSF6, and IDE) that also fell within the broad area of linkage. A total of 50 SNPs were genotyped across the genes in the family-based data set and an independent case-control data set containing 483 cases and 879 controls. Of the 50 SNPs in the five candidate genes, 22 gave nominally significant association results in at least one data set, with at least one positive SNP in each gene. SNPs rs2441718 and rs2456737 in VR22 (67.8 Mb) showed association in both family-based and case-control data sets (both P=0.03). A two-point logarithmic odds (LOD) score of 2.69 was obtained at SNP rs1890739 (45.1 Mb, P=0.03 in 21% of the families) when the families were ordered from low to high by ApoE LOD score using ordered subset analysis (OSA). These data continue to support a role for chromosome 10 loci in AD. However, the candidate gene and linkage analysis results did not converge, suggesting that there is more extensive heterogeneity on chromosome 10 than previously appreciated.

Universal behaviour of silica suspensions gelled under shear

The shear-influenced gelation of three aqueous suspensions consisting of silica particles of nominal diameter 7, 12 and 24 nm, respectively, is reported. It is shown that the viscosity/stress of a gelling system increases with time after gel initiation, reaches a maximum, then falls to a plateau value. A very simple relation between this maximum stress and the precursor volume fraction is verified experimentally.

No association between SNP rs498055 on chromosome 10 and late-onset Alzheimer disease in multiple datasets

SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset >or= 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD.