Arto Mannermaa

A common coding variant in CASP8 is associated with breast cancer risk

The Breast Cancer Association Consortium (BCAC) has been established to conduct combined case-control analyses with augmented statistical power to try to confirm putative genetic associations with breast cancer. We genotyped nine SNPs for which there was some prior evidence of an association with breast cancer: CASP8 D302H (rs1045485), IGFBP3 −202 C → A (rs2854744), SOD2 V16A (rs1799725), TGFB1 L10P (rs1982073), ATM S49C (rs1800054), ADH1B 3′ UTR A → G (rs1042026), CDKN1A S31R (rs1801270), ICAM5 V301I (rs1056538) and NUMA1 A794G (rs3750913). We included data from 9–15 studies, comprising 11,391–18,290 cases and 14,753–22,670 controls. We found evidence of an association with breast cancer for CASP8 D302H (with odds ratios (OR) of 0.89 (95% confidence interval (c.i.): 0.85–0.94) and 0.74 (95% c.i.: 0.62–0.87) for heterozygotes and rare homozygotes, respectively, compared with common homozygotes; Ptrend = 1.1 × 10−7) and weaker evidence for TGFB1 L10P (OR = 1.07 (95% c.i.: 1.02–1.13) and 1.16 (95% c.i.: 1.08–1.25), respectively; Ptrend = 2.8 × 10−5). These results demonstrate that common breast cancer susceptibility alleles with small effects on risk can be identified, given sufficiently powerful studies.NOTE: In the version of this article initially published, there was an error that affected the calculations of the odds ratios, confidence intervals, between-study heterogeneity, trend test and test for association for SNP ICAM5 V301I in Table 1 (ICAM5 V301I); genotype counts in Supplementary Table 2 (ICAM5; ICR_FBCS and Kuopio studies) and minor allele frequencies, trend test and odds ratios for heterozygotes and rare homozygotes in Supplementary Table 3 (ICAM5; ICR_FBCS and Kuopio studies). The errors in Table 1 have been corrected in the PDF version of the article. The errors in supplementary information have been corrected online.

Apolipoprotein E 4 Allele, Elevated Midlife Total Cholesterol Level, and High Midlife Systolic Blood Pressure Are Independent Risk Factors for Late-Life Alzheimer Disease

Context Apolipoprotein E (apoE) 4 allele, elevated total cholesterol level, and hypertension are risk factors for late-life Alzheimer disease. Are these risk factors independent, or do the effects of apoE polymorphism on cholesterol metabolism mediate the association between apoE and Alzheimer disease? Contribution In this long-term, prospective population-based study, apoE, elevated total cholesterol level, and elevated systolic hypertension increased the risk for Alzheimer disease in an independent and additive manner. Implications The mechanism by which apoE polymorphism contributes to the development of Alzheimer disease appears different than the mechanism that mediates its effect on cholesterol level. Some risk factors for Alzheimer disease (dyslipidemia and systolic hypertension) are potentially treatable, while others (apoE) are not. The Editors Alzheimer disease is a disease of complex origin, and the exact pathogenic mechanisms remain unknown. Several environmental and genetic factors have been implicated in the development of Alzheimer disease. Two lines of research have recently shown an association between serum total cholesterol level and development of the disease. First, two independent, prospective population-based studies have reported an association between elevated midlife total cholesterol levels and late-life Alzheimer disease (1, 2). Second, two recent studies have shown a reduced rate of the disease in persons who used statins to reduce their blood total cholesterol level (3, 4). To date, only the apolipoprotein E (apoE) 4 allele, which is involved in cholesterol metabolism, has been established as a significant genetic risk factor for Alzheimer disease in the general population (5). Whether the associations of elevated level of serum total cholesterol and apoE polymorphism with Alzheimer disease are independent or interrelated is unknown. Earlier cross-sectional and short follow-up studies yielded conflicting results on the putative relationship among apoE, total cholesterol level, and Alzheimer disease (6-8). Although long-term prospective studies may be better suited for resolving this issue, only two such studies have been reported to date. The first study found that elevated serum total cholesterol level was a risk factor for Alzheimer disease, independent of the apoE 4 allele; however, the association between the apoE 4 allele and Alzheimer disease became weaker after adjustment for serum total cholesterol level (1). Thus, the authors of that study concluded that some of the effect of the apoE 4 allele on the risk for Alzheimer disease might be mediated through elevated levels of serum total cholesterol. In contrast, another prospective study suggested that the presence of the apoE 4 allele may increase the risk for Alzheimer disease, independent of its effect on dyslipidemia and atherogenesis (9). Few prospective studies have suggested that elevated blood pressure earlier in life could increase the risk for Alzheimer disease (2, 10, 11). Although the association between apoE and blood pressure appears to be vague, some studies have reported excess cognitive decline in persons with hypertension who have the apoE 4 allele (12, 13). Moreover, atherosclerosis, which can result from an elevated total cholesterol level or blood pressure, has been studied in relation to Alzheimer disease and apoE polymorphism, also with conflicting results (14, 15). Alzheimer disease is becoming an increasingly serious public health problem. Interventions that could delay disease onset could therefore have a major public health impact. The number of patients with Alzheimer disease is projected to quadruple over the next 50 years, and interventions that would postpone the onset of clinical Alzheimer disease by 5 years would decrease the prevalence of the disease by 50% (16). Alzheimer disease might be prevented by use of interventions for modifiable vascular risk factors. However, the relative importance and putative interactions between vascular risk factors and the apoE polymorphism in the development of Alzheimer disease in the general population remain to be established. We have previously reported that elevated total cholesterol level and systolic blood pressure during midlife increased the risk for Alzheimer disease (2). We recently determined the apoE genotypes in this sample and have therefore been able to study the putative relationship among the apoE 4 allele, midlife total cholesterol level, and midlife blood pressure in the development of Alzheimer disease in a prospective, population-based study setting. Methods Participants The participants in this study were derived from four separate, independent population-based samples studied within the framework of the North Karelia Project and the Finnish part of the Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (FINMONICA) studies in 1972, 1977, 1982, and 1987 (17, 18). (The survey methods were carefully standardized and followed the World Health Organization protocol for the Multinational Monitoring of Trends and Determinants in Cardiovascular Disease [MONICA] study [17].) The participation rates in these surveys were high, ranging from 82% to 92%. For the current study, we targeted past participants who were still alive at the end of 1997; 65 to 79 years of age; and who lived in or near Kuopio or Joensuu, Finland (n = 2293). We invited a random sample of 2000 persons within this group to a reexamination in 1998. Altogether, 1449 persons (72.5% of the invited sample) participated. The mean follow-up (SD) was 21.0 4.9 years (range, 11 to 26 years). (The duration of follow-up was 26 years for 34.9% of the current study sample, 21 years for 38.1%, 16 years for 15.6%, and 11 years for 11.4%.) The ethics committees of the University of Kuopio and the Kuopio University Hospital, Kuopio, Finland, approved the study protocol. All participants provided written informed consent. Midlife Visit The study protocol is described in detail elsewhere (19). In brief, the survey included a self-administered questionnaire on sociodemographic characteristics; health-related behaviors, including smoking habits and alcohol consumption; and medical history, including cerebrovascular and cardiovascular events and conditions diagnosed by a physician. Height and weight were measured. Blood pressure was measured from the right arm after the participants had been seated for 5 minutes. For most of the current study sample, only a single blood pressure measurement had been recorded in the initial survey. (In the 1972 survey, blood pressure was recorded once; for 186 of 531 participants in the 1977 survey and for all participants in the subsequent surveys, blood pressure was recorded twice.) Venous blood specimens were taken to determine serum total cholesterol levels. Serum total cholesterol level was determined in 1972 and 1977 from frozen serum samples by using the Liebermann-Burchard method; in 1982 and 1987, total cholesterol level in fresh serum samples was measured by using an enzymatic method (CHOD-PAP Monotest, Boehringer, Mannheim, Germany). The enzymatic assay yielded values that were 2.4% lower than those measured by the Liebermann-Burchard method; thus, we corrected the values for total cholesterol level from the 1972 and 1977 surveys accordingly. All cholesterol levels were determined at the same central laboratory, and the laboratory data were standardized against those of national and international reference laboratories. Reexamination in 1998 During the reexamination, the survey methods followed the standards of the previous surveys in all aspects. Cognitive impairment and dementia were diagnosed in three phases: a screening phase, a clinical phase, and a differential diagnostic phase. Cases of dementia were diagnosed according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (20); Alzheimer disease was diagnosed according to the criteria of the U.S. National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimers Disease and Related Disorders Association (21). In addition, mild cognitive impairments were diagnosed by using the criteria proposed by the Mayo Clinic Alzheimers Disease Research Center (22). Blood leukocyte samples were analyzed to determine apoE genotype. To extract DNA, we used a standard phenol-chloroform technique; apoE genotypes were analyzed by polymerase chain reaction and HhaI digestion, as described previously (23). Statistical Analyses We analyzed the data using SPSS software for Windows, version 9.0 (SPSS Inc., Chicago, Illinois). We performed a chi-square test to compare the frequency of the apoE allele between controls and participants with Alzheimer disease. We studied the association between the apoE 4 allele and Alzheimer disease by using logistic regression analyses. We present these results as odds ratios with 95% CIs. From model 1, we determined univariate odds ratios. To study whether the apoE 4 allele was associated with Alzheimer disease, independent of midlife hypercholesterolemia and elevated systolic blood pressure, we included the variables of apoE genotype (4 carriers or noncarriers), total cholesterol level, and systolic blood pressure (according to categories) in the second model (model 2). In model 2, we also adjusted for the additional variables of age, history of myocardial infarction (yes or no), history of cerebrovascular symptoms (yes or no), education (years of formal education), sex, smoking status (current smoker, former smoker, or nonsmoker), and alcohol consumption (none, <10 g/d, 10 to 30 g/d, or >30 g/d). Midlife values for serum total cholesterol were classified as high ( 6.5 mmol/L [ 251 mg/dL]) or normal (<6.5 mmol/L [<251 mg/dL]). Midlife blood pressure was classified according to the following groups: normal (<140 mm Hg), borderline (140 to 159 mm Hg), or high ( 160 mm Hg) for systolic blood pressur

A recurrent mutation in PALB2 in Finnish cancer families

BRCA1, BRCA2 and other known susceptibility genes account for less than half of the detectable hereditary predisposition to breast cancer. Other relevant genes therefore remain to be discovered. Recently a new BRCA2-binding protein, PALB2, was identified. The BRCA2–PALB2 interaction is crucial for certain key BRCA2 DNA damage response functions as well as its tumour suppression activity. Here we show, by screening for PALB2 mutations in Finland that a frameshift mutation, c.1592delT, is present at significantly elevated frequency in familial breast cancer cases compared with ancestry-matched population controls. The truncated PALB2 protein caused by this mutation retained little BRCA2-binding capacity and was deficient in homologous recombination and crosslink repair. Further screening of c.1592delT in unselected breast cancer individuals revealed a roughly fourfold enrichment of this mutation in patients compared with controls. Most of the mutation-positive unselected cases had a familial pattern of disease development. In addition, one multigenerational prostate cancer family that segregated the c.1592delT truncation allele was observed. These results indicate that PALB2 is a breast cancer susceptibility gene that, in a suitably mutant form, may also contribute to familial prostate cancer development.

Breast-Cancer Risk in Families with Mutations in PALB2

BACKGROUND Germline loss-of-function mutations in PALB2 are known to confer a predisposition to breast cancer. However, the lifetime risk of breast cancer that is conferred by such mutations remains unknown. METHODS We analyzed the risk of breast cancer among 362 members of 154 families who had deleterious truncating, splice, or deletion mutations in PALB2. The age-specific breast-cancer risk for mutation carriers was estimated with the use of a modified segregation-analysis approach that allowed for the effects of PALB2 genotype and residual familial aggregation. RESULTS The risk of breast cancer for female PALB2 mutation carriers, as compared with the general population, was eight to nine times as high among those younger than 40 years of age, six to eight times as high among those 40 to 60 years of age, and five times as high among those older than 60 years of age. The estimated cumulative risk of breast cancer among female mutation carriers was 14% (95% confidence interval [CI], 9 to 20) by 50 years of age and 35% (95% CI, 26 to 46) by 70 years of age. Breast-cancer risk was also significantly influenced by birth cohort (P<0.001) and by other familial factors (P=0.04). The absolute breast-cancer risk for PALB2 female mutation carriers by 70 years of age ranged from 33% (95% CI, 25 to 44) for those with no family history of breast cancer to 58% (95% CI, 50 to 66) for those with two or more first-degree relatives with breast cancer at 50 years of age. CONCLUSIONS Loss-of-function mutations in PALB2 are an important cause of hereditary breast cancer, with respect both to the frequency of cancer-predisposing mutations and to the risk associated with them. Our data suggest the breast-cancer risk for PALB2 mutation carriers may overlap with that for BRCA2 mutation carriers. (Funded by the European Research Council and others.).

Incidence and Risk Factors for Mild Cognitive Impairment: A Population-Based Three-Year Follow-Up Study of Cognitively Healthy Elderly Subjects

Background: Mild cognitive impairment (MCI) has attracted considerable interest as a potential predictor of Alzheimer’s disease (AD). Both the apolipoprotein E (ApoE) Ε4 allele and vascular factors have been associated with a higher risk for AD, recently they have also been linked to the risk of MCI. Objectives: To estimate the incidence of MCI among cognitively healthy elderly subjects during a 3-year follow-up, and to evaluate the impact of demographic and vascular factors as well as the ApoE Ε4 allele on the conversion to MCI. Methods: At baseline, the cognitive abilities of 806 out of 1,150 eligible subjects (aged 60–76 years) from a population-based sample were examined. Cognitively intact subjects (n = 747) were followed for an average of 3 years. Results: 66 subjects (8.8%) had converted to MCI. The global incidence rate of MCI was 25.94/1,000 person-years. Persons with higher age (OR 1.08, 95% CI 1.01–1.16), ApoE Ε4 allele carriers (OR 2.04, 95% CI 1.15–3.64) and persons with medicated hypertension (OR 1.86, 95% CI 1.05–3.29) were more likely to convert to MCI than those individuals of lower age and without an ApoE Ε4 allele or medicated hypertension. Persons with high education (OR 0.79, 95% CI 0.70–0.89) were less likely to convert to MCI than persons with low or no education. In subjects with both the ApoE Ε4 allele and medicated hypertension, the crude OR for conversion was 3.92 (95% CI 1.81–8.49). In subjects with cardiovascular disease, the crude OR for conversion was 2.13 (95% CI 1.26–3.60). Gender, elevated blood pressure, diabetes or cerebrovascular disease had no significant effect on the conversion to MCI. Conclusion: Higher age, the presence of at least one ApoE Ε4 allele and medicated hypertension are independent risk factors, but high education is a protective factor for MCI. The results suggest that vascular factors may have an important role in the pathogenesis of MCI.

A common variant in BRCA2 is associated with both breast cancer risk and prenatal viability.

Inherited mutations in the gene BRCA2 predispose carriers to early onset breast cancer, but such mutations account for fewer than 2% of all cases in East Anglia. It is likely that low penetrance alleles explain the greater part of inherited susceptibility to breast cancer; polymorphic variants in strongly predisposing genes, such as BRCA2, are candidates for this role. BRCA2 is thought to be involved in DNA double strand break-repair. Few mice in which Brca2 is truncated survive to birth; of those that do, most are male, smaller than their normal littermates and have high cancer incidence. Here we show that a common human polymorphism (N372H) in exon 10 of BRCA2 confers an increased risk of breast cancer: the HH homozygotes have a 1.31-fold (95% CI, 1.07–1.61) greater risk than the NN group. Moreover, in normal female controls of all ages there is a significant deficiency of homozygotes compared with that expected from Hardy-Weinberg equilibrium, whereas in males there is an excess of homozygotes: the HH group has an estimated fitness of 0.82 in females and 1.38 in males. Therefore, this variant of BRCA2 appears also to affect fetal survival in a sex-dependent manner.

NAD(P)H:quinone oxidoreductase 1 NQO1 * 2 genotype (P187S) is a strong prognostic and predictive factor in breast cancer

NQO1 guards against oxidative stress and carcinogenesis and stabilizes p53. We find that a homozygous common missense variant (NQO1*2, rs1800566(T), NM_000903.2:c.558C>T) that disables NQO1 strongly predicts poor survival among two independent series of women with breast cancer (P = 0.002, N = 1,005; P = 0.005, N = 1,162), an effect particularly evident after anthracycline-based adjuvant chemotherapy with epirubicin (P = 7.52 × 10−6) and in p53-aberrant tumors (P = 6.15 × 10−5). Survival after metastasis was reduced among NQO1*2 homozygotes, further implicating NQO1 deficiency in cancer progression and treatment resistance. Consistently, response to epirubicin was impaired in NQO1*2-homozygous breast carcinoma cells in vitro, reflecting both p53-linked and p53-independent roles of NQO1. We propose a model of defective anthracycline response in NQO1-deficient breast tumors, along with increased genomic instability promoted by elevated reactive oxygen species (ROS), and suggest that the NQO1 genotype is a prognostic and predictive marker for breast cancer.

A severe loss of choline acetyltransferase in the frontal cortex of Alzheimer patients carrying apolipoprotein ε4 allele

We measured the activities of choline acetyltransferase (ChAT) in the post mortem frontal cortex in 32 Alzheimers disease (AD) patients with different apolipoprotein E (apoE) genotypes. The ChAT values were significantly lower for the AD patients with 2 e4 alleles than for those with 0 e4 (ANOVA, P < 0.05). The ChAT activities of AD patients carrying 2 or 1 e4 alleles and those without the e4 allele also differed significantly: 16.3 ± 15.2 versus 30.5 ± 20.6 pmol/mg protein per min, ANOVA, P < 0.05. However, the AD patients carrying the e4 allele were significantly younger than those with 0 e4 allele. The study indicates that AD patients carrying the e4 allele have a more severe cholinergic deficit than the AD patients without the e4 allele.

Volumes of hippocampus, amygdala and frontal lobe in Alzheimer patients with different apolipoprotein E genotypes

An increased frequency of apolipoprotein E E4 allele has been reported in patients with late onset Alzheimers disease. Apolipoprotein E participates in the transport of cholesterol and other lipids and interferes with the growth and regeneration of both peripheral and central nervous system tissues during development and after injury. Apolipoprotein E is also implicated in synaptogenesis. Apolipoprotein E isoforms differ in binding to amyloid-beta-protein and tau protein in vitro. Here, we wanted to study the effect of apolipoprotein E genotype on the magnitude of damage in the hippocampus, where a marked synapse loss exists in Alzheimers disease. We measured by magnetic resonance imaging the volumes of the hippocampus, amygdala, and frontal lobes in the three Alzheimer subgroups: patients with 2, 1 or 0 E4 alleles. We also investigated the profile of deficits on tests assessing memory, language, visuospatial, executive, and praxic functions of these Alzheimer subgroups. All Alzheimer patients were at early stage of the disease. We found that Alzheimer patients with E4/4 genotype (N = 5) had smaller volumes of the hippocampus and the amygdala than those with E3/4 (N = 9) and those with E3/3 or E2/3 (N = 12). The difference was significant for the right hippocampus (-54% of control) and the right amygdala (-37% of control). The volumes of the frontal lobes were similar across the Alzheimer subgroups. The patients with E4/4 also showed lowest scores on delayed memory tests and differed from E3/3, 3/2 patients in the list learning test (< 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and neuropsychological characteristics in familial and sporadic Alzheimer's disease: Relation to apolipoprotein E polymorphism

Alzheimers disease (AD) is a heterogeneous entity presenting as sporadic and familial disease.In familial AD, there is evidence for genetic linkage to a yet undefined gene on chromosome 14 in early-onset pedigrees and on chromosome 19 in late-onset pedigrees. In a few early-onset kindreds, there were mutations in the amyloid precursor gene on chromosome 21. There is an increased frequency of apolipoprotein E (ApoE) epsilon 4 allele in patients with late-onset AD. We studied the clinical presentation and profile of cognitive deficits in 58 AD patients at the early stage of the disease. We divided the AD patients into subgroups of sporadic late-onset (SLO) (more than equals to 65 years), familial late-onset (FLO) (more than equals to 65 years), sporadic early-onset (SEO) (less than 65 years), and familial early-onset (FEO) (less than 65 years) patients and into three subgroups according to their ApoE genotype zero epsilon 4, one epsilon 4, and two epsilon 4 alleles. The AD subgroups did not differ in the global clinical severity of dementia or the duration of the disease. SLO, FLO, SEO, and FEO subgroups did not differ in clinical characteristics such as occurrence of rigidity, hypokinesia, tremor, myoclonus, hallucinations, delusions, or epileptic seizures nor in the profile of deficits on tests assessing memory, language, visuospatial, executive, and praxic functions. The epsilon 4 allele frequency was 0.43 for all AD patients and did not differ across subgroups divided according to the familial aggregation and age of onset. Patients with two epsilon 4 alleles had earlier age at onset of dementia than those with no epsilon 4 allele (63 plus minus 9 versus 68 plus minus 9 years), but otherwise the clinical symptoms and signs were not related to the ApoE genotype. However, the AD patients with two epsilon 4 alleles had lowest scores on memory tests and differed significantly from those with one or zero epsilon 4 allele in the delayed list learning (p less than 0.05) and from those with zero epsilon 4 allele in the immediate and delayed story recall. In contrast, verbal functions were better preserved in two epsilon 4 patients than in those with other ApoE genotypes. This study failed to confirm the earlier reports of severe aphasia, agnosia, and apraxia in familial AD patients, but the clinical phenotype was similar irrespective to the familial aggregation. However, AD patients with two epsilon 4 alleles are characterized by more severe memory loss and earlier age of onset than those without the epsilon 4 allele. NEUROLOGY 1996;46: 413-419