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J L Hopper

Publications and source records attributed to J L Hopper.

At least 55 records · Page 3Linked to original sources
PubMed2000

After BRCA1 and BRCA2-what next? Multifactorial segregation analyses of three-generation, population-based Australian families affected by female breast cancer.

Mutations in BRCA1 and BRCA2 that cause a dominantly inherited high risk of female breast cancer seem to explain only a small proportion of the aggregation of the disease. To study the possible additional genetic components, we conducted single-locus and two-locus segregation analyses, with and without a polygenic background, using three-generation families ascertained through 858 women with breast cancer diagnosed at age <40 years, ascertained through population cancer registries in Melbourne and Sydney, Australia. Extensive testing for deleterious mutations in BRCA1 and BRCA2, to date, has identified 34 carriers. Our analysis suggested that, after other possible unmeasured familial factors are adjusted for and the known BRCA1 and BRCA2 mutation carriers are excluded, there appears to be a residual dominantly inherited risk of female breast cancer in addition to that derived from mutations in BRCA1 and BRCA2. This study also suggests that there is a substantial recessively inherited risk of early-onset breast cancer. According to the best-fitting model, after excluding known carriers of mutations in BRCA1 and BRCA2, about 1/250 (95% confidence interval [CI] 1/500 to 1/125) women have a recessive risk of 86% (95% CI 69%-100%) by age 50 years and of almost 100% by age 60 years. Possible reasons that our study has implicated a novel strong recessive effect include our inclusion of data on lineal aunts and grandmothers, study of families ascertained through women with early-onset breast cancer, allowance for multiple familial factors in the analysis, and removal of families for whom the cause (i.e., BRCA1 or BRCA2) is known. Our findings may have implications for attempts to identify new breast cancer-susceptibility genes.

Age Factors↗
PubMed2000

CYP17 promoter polymorphism and breast cancer in Australian women under age forty years.

BACKGROUND: The cytochrome P450c17alpha enzyme functions in the steroid biosynthesis pathway, and altered endogenous steroid hormone levels have been reported to be associated with a T to C polymorphism in the 5' promoter region of the CYP17 gene. Because steroid hormone exposure is known to influence breast cancer risk, we conducted a population-based, case-control-family study to assess the relationship between the CYP17 promoter polymorphism and early-onset breast cancer. METHODS: Case subjects under 40 years of age at diagnosis of a first primary breast cancer, population-sampled control subjects, and the relatives of both case and control subjects were interviewed to record family history of breast cancer and other risk factors. CYP17 genotype was determined in 369 case subjects, 284 control subjects, and 91 relatives of case subjects. Genotype distributions were compared by logistic regression, and cumulative risk was estimated by a modified segregation analysis. All statistical tests were two-tailed. RESULTS: Compared with the TT genotype (i.e., individuals homozygous for the T allele), the TC genotype was not associated with increased breast cancer risk (P: =.7). Compared with the TT and TC genotypes combined, the CC genotype was associated with a relative risk of 1. 81 (95% confidence interval [CI] = 1.15-2.86; P: =.01) before adjustment for measured risk factors and 1.63 (95% CI = 1.00-2.64; P: =.05) after adjustment. There was an excess of CC genotypes in case subjects who had at least one affected first- or second-degree relative, compared with control subjects unstratified by family history of breast cancer (23% versus 11%; P: =.006), and these case subjects had a threefold to fourfold higher risk than women of other groups defined by genotype and family history of breast cancer. Analysis of breast cancer in first- and second-degree relatives of case subjects with the CC genotype, excluding two known carriers of a deleterious mutation in BRCA1 or BRCA2, gave a relative hazard in women with the CC genotype of 3.48 (95% CI = 1.13-10.74; P: =.04), which is equivalent to a cumulative risk of 16% to age 70 years. CONCLUSIONS: The CC genotype may modify the effect of other familial risk factors for early-onset breast cancer.

Adult↗
PubMed2000

Familial patterns of covariation for cardiovascular risk factors in adults: The Victorian Family Heart Study.

The Victorian Family Heart Study was established to address the causes of familial patterns in cardiovascular risk factors. From 1990 to 1996, a representative population sample of 783 adult families (2,959 individuals), each comprising both parents (40-70 years) and at least one natural adult offspring (18-30 years), was recruited in Melbourne, Australia. Included in both generations were 461 monozygotic and dizygotic twins as pairs or singletons. A multivariate normal model was used for pedigree analysis of height, weight, body mass index, diastolic and systolic blood pressure, pulse rate, and total and high density lipoprotein cholesterol. All traits showed evidence for additive genetic variation, explaining from 55% (height) to 26% (pulse) of age- and sex-adjusted variance. An effect persisting into adulthood of shared family environment during cohabitation explained from 39% (body mass index) to 13% (systolic blood pressure) of variance (not nominally significant for diastolic blood pressure). These shared environmental effects were strongest within twin pairs, less so for sibling pairs, and least for parent-offspring pairs (in which an effect was not observed for weight, diastolic and systolic blood pressure, and total cholesterol). On a background of genetic influences, there are periods in early life during which the family environment cements long-term correlations between adult relatives in cardiovascular risk factors.

Adult↗
PubMed2000

Androgen receptor exon 1 CAG repeat length and risk of ovarian cancer.

Epidemiological studies indicate that ovarian cancer is an endocrine-related tumour. We conducted a case-control comparison to assess the androgen receptor (AR) exon 1 polymorphic CAG repeat length (CAG(n)) as a risk factor for epithelial ovarian cancer. AR CAG(n) was determined for 319 case subjects with ovarian adenocarcinoma and 853 unaffected control subjects (comprising 300 unrelated adult female monozygotic twins, and 553 adult females sampled randomly from the population using the electoral rolls). The CAG(n) distributions of case subjects and control subjects were compared as a continuum, and by dichotomising alleles according to different CAG(n) cut-points. Logistic regression was used to calculate age-adjusted odds ratio (OR) estimates. Analyzed as a continuous variable, there was no difference between case subjects and control subjects for the smaller, larger or average allele sizes of the CAG(n) genotype, before or after adjusting for age. The mean (95% CI) for the average CAG(n) was 22.0 (21.8-22.2) for case subjects and 22.0 (21.9-22.1) for control subjects (p>.9). Analysis of CAG(n) as a dichotomous variable showed no difference between case subjects and control subjects for the median cutpoint (>/= 22), or for another cut-point previously reported to act as a modifier of breast cancer risk (>/= 29). Our data provide no evidence for an association between ovarian cancer risk and the genotype defined by the AR exon 1 CAG(n) polymorphism, although we cannot exclude small effects, or threshold effects in a small subgroup.

Adenocarcinoma↗
PubMed2000

A prospective population-based study of menopausal symptoms.

OBJECTIVE: To identify symptoms that change in prevalence and severity during midlife and evaluate their relationships to menopausal status, hormonal levels, and other factors. METHODS: In a longitudinal, population-based study of 438 Australian-born women observed for 7 years with an 89% retention rate, 172 advanced from premenopause to perimenopause or postmenopause. Annual measures included a 33-item symptom check list; psychosocial, lifestyle, and health-related factors; menstrual status; hormone usage; and blood levels of follicle-stimulating hormone and estradiol (E2). RESULTS: Increasing from early to late perimenopause were the number of women who reported five or more symptoms (+14%), hot flushes (+27%), night sweats (+17%) and vaginal dryness (+17%) (all P <.05). Breast soreness-tenderness decreased with the menopausal transition (-21%). Trouble sleeping increased by +6%. The major change in prevalence was from early to late perimenopause, except for insomnia, which showed a gradual increase. Those variables most related to onset of hot flushes were number of symptoms at early perimenopause (P <.05), having an unskilled or no occupation (P <.05), more than 10 pack-years of smoking (P <.01), and decreased E2 (P <.01). The onset of night sweats increased with the change in E2 (P <.05). The onset of vaginal dryness decreased with more years of education (P <.05). Trouble sleeping was predicted by prior lower well-being (P <.01), belief at baseline that women with many interests hardly notice menopause (P <.01), and hot flushes (P <.01). CONCLUSION: Although middle-aged women are highly symptomatic, the symptoms that appear to be specifically related to hormonal changes of menopausal transition are vasomotor symptoms, vaginal dryness, and breast tenderness. Insomnia reflected bothersome hot flushes and psychosocial factors.

Adult↗
PubMed2000

Adaptive evolution of the tumour suppressor BRCA1 in humans and chimpanzees. Australian Breast Cancer Family Study.

Mutations in BRCA1 (ref. 1) confer an increased risk of female breast cancer. In a genome-wide scan of linkage disequilibrium (LD), a high level of LD was detected among microsatellite markers flanking BRCA1 (ref. 3), raising the prospect that positive natural selection may have acted on this gene. We have used the predictions of evolutionary genetic theory to investigate this further. Using phylogeny-based maximum likelihood analysis of the BRCA1 sequences from primates and other mammals, we found that the ratios of replacement to silent nucleotide substitutions on the human and chimpanzee lineages were not different from one another (P=0.8), were different from those of other primate lineages (P=0.004) and were greater than 1 (P=0.04). This is consistent with the historic occurrence of positive darwinian selection pressure on the BRCA1 protein in the human and chimpanzee lineages. Analysis of genetic variation in a sample of female Australians of Northern European origin showed evidence for Hardy-Weinberg (HW) disequilibrium at polymorphic sites in BRCA1, consistent with the possibility that natural selection is affecting genotype frequencies in modern Europeans. The clustering of between-species variation in the region of the gene encoding the RAD51-interaction domain of BRCA1 suggests the maintenance of genomic integrity as a possible target of selection.

Adaptation, Biological↗
PubMed2000

Yield from colonoscopic screening in people with a strong family history of common colorectal cancer.

BACKGROUND AND AIMS: People with a strong family history of common (so-called 'sporadic') colorectal cancer are generally advised to undergo colonoscopic screening, but the starting age for this is unclear. An audit was performed to study the age-related yield of screening colonoscopy in this risk group. METHODS: A prospective audit of the outcome of screening colonoscopy was performed on a cohort of 232 people with a strong family history of common colorectal cancer. All were registrants in a familial bowel cancer service solely because of their family medical history. They had no bowel symptoms and no prior endoscopic investigation of the large bowel. RESULTS: Neoplastic lesions were detected by using colonoscopy in 33 participants. In 27 participants, the major lesion was a small tubular adenoma, four had an advanced adenoma and two had cancer. More neoplastic (P= 0.02) and advanced neoplastic (P= 0.03) lesions were found in those patients aged > or = 50 years. Only one advanced adenoma was detected in a participant below the age of 50 years. CONCLUSION: The yield from screening colonoscopy in young people (< 50 years) with a strong family history of common colorectal cancer is low, placing doubt on the need for colonoscopic screening before the age of 50 years.

Adult↗
PubMed2000

Evidence for genetic associations between asthma, atopy, and bronchial hyperresponsiveness: a study of 8- to 18-yr-old twins.

We measured asthma in the last 12 mo, diagnosed by a respiratory physician at interview; atopy, defined by a positive skin prick test to any of eight common allergens; and bronchial hyperresponsiveness (BHR) to hypertonic saline, in 381 twin pairs aged 8 to 18 yr selected from the Australian Twin Registry-183 monozygous (MZ) and 198 dizygous (DZ). The associations between twins, as measured by an odds ratio, were greater in MZ pairs compared with DZ pairs for asthma: 25.6 (95% confidence interval 11.3- 57.8) versus 1.9 (1.0-3. 5); atopy: 14.6 (7.1-30.1) versus 2.5 (1.4- 4.5); and BHR: 14.1 (6. 4-31.0) versus 4.2 (2.1-8.6) (all p < 0.002). The associations between each pair of traits within an individual were slightly greater than the association between one trait in a twin and the other trait in the cotwin (cross-trait cross-pair) in MZ pairs. Further, the associations in MZ pairs were greater than in DZ pairs (p < 0.05). Under the assumptions of the classic twin model, these data suggest that the strong cross-sectional associations between these three traits are due to an overlap between the genetic factors involved in each of these three traits.

Adolescent↗
PubMed2000

A prospective longitudinal study of serum testosterone, dehydroepiandrosterone sulfate, and sex hormone-binding globulin levels through the menopause transition.

The aims of this study were to describe, in relation to date of final menses, the average androgen levels of women in the years before and after this date, and to determine the extent to which these average levels were dependent on age and body mass index (BMI) and the degree of tracking in residual androgen levels, or the extent to which individuals above (below) the mean for their age or time relative to final menstrual period (FMP) and BMI remain above (below) the mean as time progresses. Serial levels of serum sex hormone-binding globulin (SHBG), testosterone (T), and dehydroepiandrosterone sulfate (DHEAS) were measured annually in 172 women from the Melbourne Women's Midlife Health Project who experienced a natural menopause during 7 yr of follow-up. Fasting blood samples were drawn between days 4-8 if women were still menstruating or after 3 months of amenorrhea. The free androgen index (FAI) was calculated as the ratio ofT to SHBG x 100. Means of the log-transformed androgen levels were analyzed as a double logistic function of time relative to FMP as well as age and BMI, and correlations between repeated androgen levels were measured. Mean SHBG levels decreased by 43% from 4 yr before to 2 yr after the FMP. The time of most change was 2 yr before FMP [95% confidence interval (CI), 0.8-3.2]. SHBG levels were, on the average, 5% lower for each halving of estradiol (E2) levels and 4% lower for each kilogram per m2 of BMI (P < 0.0001). About one third of the decline in SHBG was explained by E2 and BMI. After adjusting for all variables, SHBG showed strong tracking. Mean T levels did not vary with time relative to FMP and were independent of age and BMI. Residual values of T showed weak tracking. The FAI increased by 80% from 4 yr before FMP to 2 yr after FMP, and changed maximally 2.2 yr before FMP (95% CI, 1.2-3.2). The FAI was not related to age or E2, but was, on the average, 4% higher for each kilogram per m2 of BMI (P < 0.0001). Residual values of FAI showed moderate tracking. Mean DHEAS levels were not related to the FMP, but were 1.5% lower for each year of age (P < 0.01) and 3.8% lower for each kilogram per m2 of BMI (P < 0.0001). Residual values of DHEAS showed strong tracking. It is concluded that SHBG and FAI levels change at the time of the menopause, at least partially due to the decline in E2. DHEAS decreases as a function of age, not time relative to FMP, and T remains unchanged during the menopausal years. SHBG and DHEAS show a high degree of stability within an individual over time.

Adult↗
PubMed2000

Why are the majority of hereditary cases of early-onset breast cancer sporadic? A simulation study.

Population-based studies, including those of Ashkenazi Jews, have observed that at least 50% of women with early-onset breast cancer who carry a germ line mutation in BRCA1 or BRCA2 do not report a family history of the disease. That is, the majority of "hereditary" cases are "sporadic." Furthermore, the great majority of "familial breast cancers" are not hereditary. We conducted a simulation study to evaluate the probability that a woman with early-onset breast cancer is a mutation carrier, given the number of affected relatives, for a range of plausible values of allele frequency (0.001-0.01), and increased risk in mutation carriers (5-20, equivalent to cumulative risks to age 70 of 25-70%, respectively, for Australian women). Families consisted of a case proband and her mother, sisters, and maternal and paternal grandmothers, and aunts. The numbers of sisters and aunts were generated according to Poisson distributions, and ages were assigned according to a Weibull distribution. The simulated distributions of family history and of the prevalence of mutation carriers among case probands were in general similar to those observed in population-based studies, although there was a suggestion of heterogeneity of breast cancer risk in mutation carriers. As is being observed empirically in population-based samples, a family history of breast cancer was not a strong predictor of mutation status; each affected female relative increased the risk of being a mutation carrier by only 2- to 3-fold. The probability of being a mutation carrier was generally low, except in families with extreme histories of breast cancer.

Adult↗
PubMed1999

HRAS1 rare minisatellite alleles and breast cancer in Australian women under age forty years.

BACKGROUND: A recent meta-analysis of 23 studies supported the empirically derived hypothesis that women who lack one of the four common minisatellite alleles at the HRAS1 locus are at increased risk of breast cancer. These studies relied on visual sizing of alleles on electrophoretic gels and may have underreported rare alleles. We determined whether this hypothesis applied to early-onset breast cancer by using a new method to size minisatellite alleles. METHODS: We conducted a population-based, case-control-family study of 249 Australian women under 40 years old at diagnosis of a first primary breast cancer and 234 randomly selected women, frequency matched for age. We sized HRAS1 minisatellite alleles with an Applied Biosystems model 373 automated DNA sequencer and GENESCAN(TM) software. All P values are two-sided. RESULTS: We found no association of rare alleles with breast cancer, before or after adjustment for risk factors and irrespective of how their effects were modeled (crude odds ratio = 1.04; 95% confidence interval [CI] = 0.071-1.53; P =.8). The rare allele frequency was 0. 173 (95% CI = 0.149-0.197), three times the pooled estimate of 0.058 (95% CI = 0.050-0.066) from previous studies (P<.001), and was similar for case subjects, 0.177 (95% CI = 0.143-0.221), and control subjects, 0.169 (95% CI = 0.135-0.203) (P =.7). CONCLUSION: There was no support for an association between rare HRAS1 alleles and the risk of early-onset breast cancer, despite 80% power to detect effects of the magnitude of those associations (1.7-fold) previously suggested. IMPLICATIONS: The question of whether cancer risk is associated with rare minisatellite HRAS1 alleles needs to be revisited with the use of new methods that have a greater ability to distinguish rare alleles from similarly sized common alleles.

Adult↗
PubMed1999

Androgen receptor exon 1 CAG repeat length and breast cancer in women before age forty years.

BACKGROUND: We conducted a population-based, case-control-family study to determine whether androgen receptor (AR) exon 1 polymorphic CAG repeat length (CAGn) was a risk factor for early-onset breast cancer in the Australian population. METHODS: Case subjects under 40 years of age at diagnosis of a first primary breast cancer and age-matched control subjects were interviewed to assess family history and other risk factors. AR CAGn length was determined for 368 case subjects and 284 control subjects. Distributions in the two groups were compared by linear and logistic regression, allowing adjustment for measured risk factors. All statistical tests were two-tailed. RESULTS: When analyzed as either a continuous or a dichotomous variable, there was no association between CAG, length and breast cancer risk, before or after adjustment for risk factors. Mean (95% confidence interval [CI]) CAGn lengths were 22.0 (21.8-22.2) for case subjects and 22.0 (21.7-22.3) for control subjects (P = .9). The frequency (95% CI) of alleles with 22 or more CAGn repeats was 0.531 (0.494-0.568) for case subjects and 0.507 (0.465-0.549) for control subjects (P = .4). After adjustment, the average effect on log OR (odds ratio) per allele was 0.16 (95% CI = -0.03 to 0.40; P = .2), and the effect of any allele was equivalent to an OR of 1.40 (95% CI = 0.94-2.09; P = .1). Stratification by family history also failed to reveal any association. Similar results were obtained when alleles were defined by other cutoff points. CONCLUSION: We found no evidence for an association between AR exon 1 CAGn length and breast cancer risk in women under the age of 40, despite having 80% power to detect modest effects.

Adult↗
PubMed1999

Distinct molecular pathogeneses of early-onset breast cancers in BRCA1 and BRCA2 mutation carriers: a population-based study.

Breast cancers arising in women with and without a germline mutation in the BRCA1 or BRCA2 gene display different histological features, which suggests unique mechanisms of molecular pathogenesis: We used a molecular pathological analysis to define the genetic abnormalities relevant to these specific pathogeneses. Tumor material was studied from 40 women with breast cancer diagnosed before 40 years of age, sampled from a population-based study and stratified by BRCA1 and BRCA2 germline mutation status. Cases were not selected for family history or ethnic origin, and none were known to be genetically related. Thus, germline mutation itself is likely to impact on the molecular pathogenesis of these tumors, with no substantial influence due to modifying genetic or environmental factors. Breast cancers occurring in BRCA1 mutation carriers had significantly higher levels of p53 expression, including the preinvasive (carcinoma in situ) stage of disease, compared with cancers occurring in BRCA2 mutation carriers or women with no detectable germline mutation. These cancers also had a higher proliferation rate as measured by Ki-67 antibody. Expression of the prognostic factors c-erbB-2, cyclin D1, and estrogen receptor was significantly less common in BRCA1 mutation carriers. Lower levels of cyclin D1 were also found in cancers from BRCA2 mutation carriers compared with non-mutation carriers. Direct p53 mutation analysis revealed mutations in 18% of all of the early-onset breast cancers within the study and included rare insertion and deletional mutations in cancers from BRCA1 mutation carriers. Our data indicate that a BRCA1 breast cancer phenotype may be recognized by an exceptionally high proliferation rate and early and frequent p53 overexpression but infrequent selection for overexpression of several other prognostic factor proteins known to be involved in breast oncogenesis. In contrast, breast cancers arising in BRCA2 mutation carriers have a more heterogeneous phenotypic profile.

Age of Onset↗
PubMed1999

Likelihood-based approach to estimating twin concordance for dichotomous traits.

Genetic epidemiologists are well aware that the casewise and pairwise twin concordances are two different measures. In determining appropriate estimators for each of these measures, the method of ascertainment must be considered. Here, we derive expressions for the concordance estimators and their asymptotic variances appropriate to different twin ascertainment schemes using a likelihood framework, and apply these formulas to existing data. We emphasize the distinction between concordance measures (i.e., the parameters of interest) and the concordance estimators based on the number of pairs observed. Under random or complete ascertainment the casewise estimator is asymptotically unbiased for the casewise concordance, and the pairwise estimator is asymptotically unbiased for the pairwise concordance. Under incomplete ascertainment, the casewise estimator is biased for the casewise concordance, the pairwise estimator is biased for the pairwise concordance, but the probandwise estimator is asymptotically unbiased for the casewise concordance. One can extend the likelihood equations presented here to allow the concordance parameter of interest to depend on zygosity and, if measured, other factors such as cohabitation status and similarity for genetic markers, while concurrently allowing the disease prevalence to depend on measured covariates.

Humans↗
PubMed1999

The Mental Adjustment to Cancer (MAC) scale: replication and refinement in 632 breast cancer patients.

BACKGROUND: Assessment of adjustment of patients in cancer treatment trials is becoming more common and increasingly regarded as a useful outcome measure. The widely used Mental Adjustment to Cancer (MAC) Scale was designed to measure Fighting Spirit (FS), Anxious Preoccupation (AP), Helpless-hopelessness (HH) and Fatalism. METHODS: Questionnaire responses from 632 breast cancer patients were randomly divided into two groups, one for exploratory analyses and possible scale refinement, and the other for validation purposes. RESULTS: Estimates of reliability (Cronbach's alpha) were satisfactory for two scales, FS (alpha = 0.85) and HH (alpha = 0.81), but lower for AP (alpha = 0.65) and Fatalism (alpha = 0.64). Exploratory factor analysis suggested that the MAC Scale might be measuring six independent constructs including two related to Fighting Spirit (Positive Orientation to the Illness, Minimizing the Illness), two related to Fatalism (Fatalism-revised, Loss of Control), a construct we have named Angst, and an unchanged HH construct. Scales developed to measure these constructs were satisfactorily replicated in confirmatory analyses but some reliabilities were lower than desirable. The general structure of the MAC Scale remained little changed despite the division of two scales and the suggested removal of six items. The refined scales correlated with the Hospital Anxiety and Depression scale and the Medical Coping Modes Questionnaire, indicating good concurrent validity. CONCLUSIONS: While reasonable reliability of the original scales persists through analyses of the MAC Scale, the original factor structure could not be reproduced. Six refined constructs with strong construct validity were identified within the overall domain of mental adjustment to cancer.

Adaptation, Psychological↗