The importance of family history in cerebrovascular disease

Studies of twin responses to understand exercise THerapy (STRUETH): Cerebrovascular function

KEY POINTS

Characterising individual responses to resistance and endurance exercise training can inform optimal strategies for exercise prescription. This study utilised monozygotic and dizygotic twins in a randomised cross-over study to determine individual responsiveness to different modalities of exercise training. The influence of environment versus genetics in cerebrovascular responses to training was determined. It is apparent that individuals respond differently to distinct exercise stimuli and that switching modality may be a beneficial way to obtain positive responses in cerebrovascular function. This study has implications for improving individualised exercise prescription to maintain or improve cerebral structure and function.

ABSTRACT

Introduction We studied monozygotic (MZ) and dizygotic (DZ) twin pairs following resistance (RES) and endurance (END) training to assess genetic and environmental contributions to cerebrovascular function. Methods Cerebrovascular function (rest, autoregulation, hypercapnia, exercise) was assessed in 86 healthy same-sex MZ (30 pairs) and DZ (13 pairs) twins, who underwent three-months of END and RES. Carbon dioxide (P_ET CO₂ ), mean arterial pressure (MAP) and middle cerebral artery velocity (MCAv) were measured and MCAv resistance (MCA_CVRi ) was calculated. Results Resting MCAv reduced by -2.8 cm/s following RES (P = 0.024), with no change following END (-0.3 cm/s, P = 0.758). Change in MCA_CVRi following RES was +0.11 mmHg/cm/s (P < 0.001), which was significantly greater than END (+0.02 mmHg/cm/s, P = 0.030). MAP also increased following RES (+4 mmHg, P = 0.010), but not END (+1 mmHg, P = 0.518). No changes were apparent in P_ET CO₂ . At rest, positive response rates following RES ranged from 27-71% and 40-64% following END. Intraclass correlations between twins were moderate for most variables at baseline. In response to training, only MZ pairs were significantly correlated for change in MCAv (P = 0.005) and low frequency phase (P = 0.047) following RES. Conclusion This study is the first to compare cerebrovascular function following RES and END in MZ and DZ twins. Most individuals who did not respond to one modality were able to respond by switching modality and baseline heritability estimates were higher than training response. Exercise professionals should therefore consider modality and environmental factors when optimising interventions. Abstract figure legend Schematic summary of the assessment battery of cerebrovascular measures of function and health developed by Ainslie and Green. Transcranial Doppler (TCD) measures are complemented by contemporaneous assessment of whole brain blood flow, derived from simultaneous high-resolution ultrasound via insonation of the internal carotid and vertebral arteries. Results show that group response does not always reflect individual responses, and that switching exercise modality can increase individual responsiveness to exercise training. Low twin correlations in response to exercise training indicate nurture has a larger contribution to training response than nature. This article is protected by copyright. All rights reserved.

Methods for Polygenic Traits

An important aspect of public health is disease prediction and health promotion through better targeting of preventive strategies. Well-targeted preventive strategies will eventually decrease burden of diseases and thus precise prediction plays a crucial role in public health. Many investigators put efforts into finding models that improve prediction using known risk factors of diseases. Recently with the overwhelming load of genetic loci discovered for complex diseases through genome-wide association studies (GWAS), much of attention has been focused on the role of these genetic loci to improve prediction models. Genetic loci in solo explain little variance of diseases. It is thus necessary to create new genetic parameters that combine the effect of as many genetic loci as possible. Such new parameters aim to better distinguish individuals who will develop a disease from those who will not. In this chapter, various polygenic methods that use multiple genetic loci to directly or indirectly improve precision of genetic prediction are discussed.

Mycophenolate mofetil prevents cerebrovascular injury in stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive rats (SHR-A3) develop strokes and progressive kidney disease as a result of naturally occurring genetic variations. We recently identified genetic variants in immune signaling pathways that contribute to end-organ injury. The present study was designed to test the hypothesis that a dysregulated immune response promotes stroke susceptibility. We salt-loaded 20 wk old male SHR-A3 rats and treated them with the immunosuppressant mycophenolate mofetil (MMF, 25 mg/kg/day po) (n = 8) or vehicle (saline) (n = 9) for 8 wk. Blood pressure (BP) was measured weekly by telemetry. Compared with vehicle-treated controls, MMF-treated SHR-A3 rats had improved survival and lower neurological deficit scores (1.44 vs. 0.125; P < 0.02). Gross morphology of the brain revealed cerebral edema in 8 of 9, and microbleeds and hemorrhages in 5 of 9 vehicle-treated rats. These lesions were absent in MMF-treated rats. Brain CD68 expression, indicating macrophage/microglial activation, was upregulated in vehicle-treated rats with microbleeds and hemorrhages but was undetectable in the brains of MMF-treated rats. MMF also prevented renal injury in SHR-A3 rats, evidenced by reduced proteinuria (albumin:creatinine) from 7.52 to 1.05 mg/mg (P < 0.03) and lower tubulointerstitial injury scores (2.46 vs. 1.43; P < 0.01). Salt loading resulted in a progressive increase in BP, which was blunted in rats receiving MMF. Our findings provide evidence that abnormal immune activation predisposes to cerebrovascular and renal injury in stroke-prone SHR-A3 rats.

Is nutritional labeling associated with individual health? The effects of labeling-based awareness on dyslipidemia risk in a South Korean population

Background

In 1995, the South Korean government made nutrition labeling compulsory, which has positively impacted patients with certain chronic diseases, such as dyslipidemia. We investigated the association between nutrition labeling-based awareness and the risk of dyslipidemia among individuals not yet diagnosed.

Methods

Our study used data from the fifth Korea National Health and Nutrition Examination Surveys administered during 2010–2014 (n = 17,687). We performed multiple or logistic regression analysis to examine the association between nutritional analysis and various outcome variables.

Results

Approximately 70 % of the respondents (n = 11,513) were familiar with nutrition labeling, of which 20 % (n = 3172) decided what food to buy based on that information. This awareness yielded mostly positive results on outcome indicators, such as triglyceride and high-density lipoprotein cholesterol levels. In general, individuals who used nutritional labels to make decisions regarding food purchases had a lower risk of dyslipidemia than individuals who did not (OR: 0.806, 95 % CI: 0.709–0.917).

Conclusion

Utilizing nutrition labels for making food choices correlated with a lower risk of dyslipidemia in certain subgroups. Based on our findings, we recommend that health policymakers and medical professionals consider promoting nutrition labeling as an alternative method for managing certain chronic diseases in South Korean patients.

Family History and Functional Outcome in Korean Stroke Patients: A Preliminary Study

OBJECTIVE

To investigate the association of family history of stroke with functional outcomes in stroke patients in Korea.

METHODS

A case-control study was conducted. A total of 170 patients who were admitted to a rehabilitation unit were included. Risk factors for stroke such as age, sex, diabetes mellitus, hypertension, atrial fibrillation, smoking, high blood cholesterol and homocysteine level, obesity, and family history of stroke were taken into account. Stroke subtypes were the following: large vessel infarct, small vessel infarct, embolic infarct, subarachnoid hemorrhage, and intracranial hemorrhage. Stroke severity as assessed with the National Institutes of Health Stroke Scale (NIHSS), functional outcomes using the Korean version of the Modified Barthel index (K-MBI), Functional Independence Measurement (FIM), and cognitive function using the Korean version of Mini-Mental State Examination (K-MMSE) were assessed at admission and discharge.

RESULTS

Subjects with a family history of stroke were more likely to have an ischemic stroke (90.7%) than were those without a family history (70.9%). The K-MBI, FIM, NIHSS, and K-MMSE scores did not show significant differences between patients with or without family history.

CONCLUSION

Family history of stroke was significantly associated with ischemic stroke, but not with functional outcomes. Other prognostic factors of stroke were not distributed differently between patients included in this study with or without a family history of stroke.

Gender association of the angiotensin-converting enzyme gene with ischaemic stroke

We examined the association of the NG011648 polymorphism (insertion/deletion) of the angiotensin-converting enzyme (ACE) gene with ischaemic stroke occurrence, subtype of ischaemic stroke and ischaemic stroke patients’ gender. Patients with first ever ischaemic stroke were recruited prospectively in a period of 18 months. Controls were matched with the patients for age, gender, and known risk factors for stroke. Demographic data, medical history, and vascular risk factors were collected. Genotypes were determined by polymerase chain reaction (PCR) and restriction enzyme analysis. Stroke and control groups were compared in regard to the prevalence of the NG011648 polymorphism. One hundred and seventy-six patients with ischaemic stroke and 178 controls were recruited and genotyped for NG011648 polymorphism (I/D) of the ACE gene. No significant difference in allele and genotype distributions emerged between control and patient groups, nor in the two subtype groups of lacunars and large artery atherosclerosis. After the data were stratified by gender, a low incidence of II homozygosity in female patients versus female controls ( p = 0.05) and male patients ( p = 0.013, Z score: -2.49) was found. Our results indicate that I/D polymorphisms may have a role in stroke onset, in respect to gender, with a possible favourable effect of II genotype in females.

Apolipoprotein E genotype in patients with cerebrovascular diseases and its effect on the disease outcome

A total of 100 hospitalized stroke patients and 30 healthy controls were included in a study aiming to determine the predictive role of ApoE genotype polymorphism for stroke outcome in the Turkish population. The most frequent ApoE genotype was epsilon3/3 reflecting Asian population polymorphic distribution. ApoE polymorphism in the Eastern Turkish population was found to be independent of stroke type, OSCP subtypes of infarction, localization of hemorrhage, severity of carotid artery stenosis, and resultant stroke outcome. Distinct polymorphic results in populations from nearby regions suggest a multifactorial pathogenesis and presence of very complex genetic factors in the development of stroke and stroke outcome.

A new estimate of family disease history providing improved prediction of disease risks

Complex diseases often aggregate within families and using the history of family members' disease can potentially increase the accuracy of the risk assessment and allow clinicians to better target on high risk individuals. However, available family risk scores do not reflect the age of disease onset, gender and family structures simultaneously. In this paper, we propose an alternative approach for a family risk score, the stratified log-rank family score (SLFS), which incorporates the age of disease onset of family members, gender differences and the relationship among family members. Via simulation, we demonstrate that the new SLFS is more closely associated with the true family risk for the disease and more robust to family sizes than two existing methods. We apply our proposed method and the two existing methods to a study of stroke and heart disease. The results show that assessing family history can improve the prediction of disease risks and the SLFS has strongest positive associations with both myocardial infarction and stroke.

Expanding the definition of a positive family history for early-onset coronary heart disease

PURPOSE

Assessing familial risk for early-onset coronary heart disease (CHD) is typically limited to first-degree relatives with early-onset CHD. To evaluate the impact of additional family history, we examined the associations between various family history definitions and early-onset CHD.

METHODS

By using the national HealthStyles 2003 survey data, we assessed associations between self-reported family history and personal history of early-onset CHD (diagnosed at or before age 60 years), adjusting for demographics, hypercholesterolemia, hypertension, and obesity.

RESULTS

Of 4,035 respondents, 60% were female and 72% were white, with a mean age of 48.8 years; 4.4% had early-onset CHD. In addition to having at least one first-degree relative with early-onset CHD, other significant associations included having at least one first-degree relative with late-onset CHD, at least one second-degree relative with early-onset CHD, and two or more affected second-degree relatives regardless of age of onset of CHD. Early-onset stroke in at least one first-degree relative and, in women, having at least one first-degree relative with diabetes were also significantly associated with early-onset CHD.

CONCLUSIONS

Family history beyond early-onset CHD in first-degree relatives is significantly associated with prevalent CHD diagnosed at or before age 60 years.

Evaluation of the angiotensin-converting enzyme insertion/deletion polymorphism and the risk of ischaemic stroke

Angiotensin-converting enzyme (ACE) gene polymorphism has been associated with increased incidence of stroke in some populations, although contradictory results have been reported. The aim of this study was to determine the allelic frequency and the genotypic distribution for ACE gene polymorphism in Turkish patients with ischemic stroke compared to appropriate healthy controls and to correlate the genetic findings with stoke type. One hundred and eight patients with ischemic stroke versus 79 healthy controls were studied for the presence of ACE gene polymorphism detected by PCR. Genotypes were defined as DD, II and ID according to the presence of the D (deletion) and I (insertion) alleles. There was no statistically significant difference in either the genotypic distribution or allelic frequency between the patients versus healthy controls (chi2 = 0.105; df = 1; p = 0.430). There was also no significant difference for ACE genotype distribution and allelic frequency within the stroke group classified according to Bamford criteria (chi2 = 4.827; df = 3; p = 0.185). Our data supports lack of association between DD genotype and/or D allele and ischemic stroke or subtypes of ischaemic stroke in the Turkish population.

Potential Confounding by Intermediate Phenotypes in Studies of the Genetics of Ischaemic Stroke

BACKGROUND

Family history (FHx) of stroke is perceived to be an important risk factor for ischaemic stroke. However, there are several intermediate phenotypes that are often involved in the aetiology of ischaemic stroke and that have a substantial genetic component themselves. We studied FHx of ischaemic heart disease (IHD), hypertension (HTN) and diabetes mellitus (DM) as risk factors for ischaemic stroke.

METHODS

We performed a systematic review of case-control and cohort studies reporting on FHx(IHD), FHx(HTN) or FHx(DM) as risk factors for stroke using bibliographic databases, and by hand searching reference lists and journals. Odds ratios of FHx as a risk factor for stroke were calculated within individual studies. We included unpublished data from two Oxfordshire population-based studies to assess effects on subtypes of ischaemic stroke.

RESULTS

We identified 54 studies that investigated the odds of stroke conferred by a positive FHx, 24 of which reported data on FHx of one or more intermediate phenotypes in addition to FHx of stroke. Most studies reported an increased frequency of FHx(IHD) and FHx(HTN) in stroke patients versus controls. The association was significant in 6 out of 14 studies for FHx(IHD) and 4 out of 11 studies for FHx(HTN). In contrast, FHx(DM) was not associated with stroke. FHx(IHD) was particularly associated with large vessel strokes (OR 1.72, CI 1.3-2.2, p = 0.00004).

CONCLUSIONS

FHx(IHD) and FHx(HTN) are both risk factors for stroke. It is likely that the apparent heritability of stroke is partly accounted for by heritability of HTN and large vessel atherosclerosis. Analyses of heritability of stroke and candidate gene studies should be adjusted accordingly.

Family history as a risk factor for stroke in young women

BACKGROUND

Family history of stroke (FHS) is associated with risk of stroke in middle-aged to elderly populations. However, few studies have examined this association in younger women or by stroke type. A population-based, case-control study was conducted to examine the association of FHS and risk of stroke in young women, and to determine whether the association is independent of other stroke risk factors.

METHODS

Cases were women aged 18 to 44 years, with first, nonfatal ischemic (n =49) and hemorrhagic (n = 63) strokes in western Washington State in 1991 to 1995. Demographically similar community controls (n = 446) were identified through random-digit telephone dialing. Information on FHS in first-degree relatives (parents and siblings) and other risk factors was obtained through an interview. Person-years (P-Y) at risk of stroke for relatives of each subject were included in polytomous logistic regression models to adjust for family size. The analysis was conducted between 1999 and 2000.

RESULTS

After adjustment for age and P-Y, FHS in first-degree relatives was significantly associated with an increased risk of hemorrhagic (odds ratio [OR]=2.6, 95% confidence interval [CI]=1.5-4.3) and ischemic stroke (OR=2.1, 95% CI=1.2-3.9). FHS remained associated with risk of hemorrhagic stroke (OR=2.4, 95% CI=1.4-4.1) and ischemic stroke (OR=1.8, 95%CI=0.9-3.5) after further adjustment for diabetes, hypertension, hypercholesterolemia, body mass index, physical activity, smoking, alcohol, and family history of myocardial infarction. Findings were similar when associations with parental and sibling FHS were examined separately.

CONCLUSIONS

Family history of stroke is a risk factor for both hemorrhagic and ischemic strokes among young women.

Angiotensin converting enzyme gene polymorphism and traditional Sasang classification in Koreans with cerebral infarction

Sasang constitutional medicine is a major branch of Korean traditional oriental medicine. Constitutions of Sasang medicine refer to Taeyangin, Taeumin, Soyangin, and Soumin. The differences of disease severity to be shown in the constitution may be due to genetic factors. Therefore, we examined interrelationship among cerebral infarction, CI, angiotensin converting enzyme (ACE) gene polymorphism, and Sasang constitutional classification. We investigated the association between ACE genotype and CI by case-control study in a Korean population. We also classified CI patients and control group into groups according to Sasang constitutional medicine. 208 CI patients and 643 controls without CI were examined. ACE genotype was determined by 7.5 % polyacrylamide gel separation after DNA amplification. The ACE/DD genotype was not associated with CI. The frequency of Taeumin of Sasang constitutional medicine in patients with CI was significantly higher than that in controls (chi2=41.202, p<0.001). However, the Taeumin constitution did not enhance the relative risk for CI in the subjects with ACE/DD genotype. Although we did not find any association between ACE gene polymorphism and CI in Koreans, there were significant differences in allele frequencies between Koreans and Europeans, but not Japanese and Chinese populations. Furthermore, we first attempted to evaluate the efficacy of Sasang constitutional medicine, and to find an association with CI.

The apolipoprotein E epsilon4 haplotype is an important predictor for recurrence in ischemic cerebrovascular disease

OBJECTIVE

To determine whether a specific apolipoprotein E (APOE) allele is a predictor for ischemic cerebrovascular disease (ICVD).

BACKGROUND

The role of APOE in atherosclerosis has been a focus of intensive research. The APOE epsilon4 allele is overrepresented in Alzheimer's disease, atherosclerosis, ischemic heart disease, and ICVD. Also, epsilon4 carriers have higher cholesterol levels than non-epsilon4 carriers.

METHODS

We performed a prospective, longitudinal study on patients who have ICVD. The patients were recruited from St. Mary Hospital, Korea, and investigated for ICVD through interviews and by reviewing their medical records and neuroimaging studies. APOE genotypes were determined for each patient.

RESULTS

20 of the 91 enrolled patients had recurrent ICVD, yielding a 3-year cumulative recurrence rate of 22%. Carriers of the epsilon4 allele had a 3-year recurrence rate of 53%, as compared with only 16% for patients who had the APOE non-epsilon4 allele (the risk ratio was 4.11; the 95% CI was 1.49-11.32; P<0.01).

CONCLUSIONS

Our results make possible the identification of patients with ICVD who are at high risk for recurrence by assessing their APOE genotype. Also, this data might be clinically useful in methods for assessing potential strategies for prevention.

Analytic strategies for stroke genetics

Strokes occur in first-degree relatives of stroke patients at rates approximating 40%; estimated population prevalences range from 3%-12%. The recent discovery of the Strk1 gene in Icelandic families, associated with a 7-fold increased stroke risk in carriers, strongly implicates a genetic contribution to stroke independent of other genetically based risk factors such as hypertension or diabetes. In this article we review the evidence for genetic contributions to stroke. We describe roles for genetic and molecular epidemiology in evaluating this complex disease. We delineate study design issues and analytic strategies to determine genetic association.

Evaluation of the atrial natriuretic peptide gene in stroke

The atrial natriuretic peptide (ANP) gene was, though inconclusive, implied to be etiologically related to stroke in rats and recently in humans. The present study tested the candidacy of ANP for stroke susceptibility by a combination of molecular genetic approaches. First, we undertook an association study using a reported ANP variant, G664A, in two case-control panels independently collected, which involved 970 Japanese subjects. Second, we compared the rat ANP gene sequences and neighboring marker alleles among stroke-prone SHR (SHRSP), normal SHR and WKY of an original inbred colony and we also compared brain ANP expression between SHRSP and normal SHR. In humans, we found no significant association between the 664A variant and stroke in the studied population. In rats, 21 polymorphic sites were identified by direct sequencing of 2170-bp ANP fragments, from which two distinct alleles, SHRSP- and WKY-types, were inferred. From a genealogical point of view, our data indicated that an SHRSP-type allele could not play a determinant role in stroke-proneness. Overall results did not support the disease relevance of ANP, disagreeing with previous reports. Thus, considerable caution should be taken when one attempts to transfer findings in the animal model to humans.

Genetic aspects of stroke: human and experimental studies

As one of the leading causes of death within both the developed and developing world, stroke is a worldwide problem. Risk factors can be identified and controlled at the level of lifestyle changes; however, genetic components of stroke have yet to be identified. The identification of such genetic components is critical in the understanding, diagnosis, and treatment of stroke in the future. This review focuses on the genetic determinants of stroke in both human and experimental systems. Mendelian disorders, candidate genes, and twin studies provide evidence for a strong genetic component of stroke. Genome-wide scanning in both human and animal models has led to the identification of regions of the genome that contain genes for stroke susceptibility and sensitivity. Animal models of stroke allow for environmental control and genetic homogeneity, not possible within a human population, and therefore are essential for the dissection of this complex, multifactorial disorder. Future genetic and genomic strategies and their role in ultimate causative gene identification are discussed.

Family history of stroke in stroke types and subtypes

Many studies have provided data showing that family history of stroke (FHS) is associated with an increased risk of stroke. The association of the FHS with the various stroke subtypes has not been adequately studied. The purpose of this study was to assess the association of the FHS with the two major stroke types (cerebral haematomas and ischaemic strokes) and the four stroke subtypes (cardioembolic, large artery disease, small artery disease, and undetermined) in a Greek population. The FHS was obtained from 421 consecutive acute stroke patients and from 239 matched control subjects. Positive FHS was observed in 49% of all stroke patients compared with 28% of the control subjects [adjusted OR=2.06 (95% confidence intervals (CI) 1.42-3.00)]. Haematomas, ischaemic strokes, and from the ischaemic strokes, both large and small artery disease strokes were strongly associated with positive FHS compared with the control subjects [adjusted OR=2.06 (95% CI 9-3.04), 2.07 (95% CI 1.09-3.91), 2.05 (95% CI 1.24-3.38), and 2.76 (95% CI 1.55-4.91), respectively]. There was no difference between maternal and paternal heritable contribution.In conclusion, FHS was found in this study to be an independent risk factor for all strokes combined, for each stroke type, and for the large and small-artery disease stroke subtypes, but not for the cardioembolic and undetermined stroke subtypes.

Localization of a susceptibility gene for common forms of stroke to 5q12

Stroke is one of the most complex diseases, with several subtypes, as well as secondary risk factors, such as hypertension, hyperlipidemia, and diabetes, which, in turn, have genetic and environmental risk factors of their own. Here, we report the results of a genomewide search for susceptibility genes for the common forms of stroke. We cross-matched a population-based list of patients with stroke in Iceland with an extensive computerized genealogy database clustering 476 patients with stroke within 179 extended pedigrees. Linkage to 5q12 was detected, and the LOD score at this locus meets the criteria for genomewide significance (multipoint allele-sharing LOD score of 4.40, P=3.9 x 10(-6)). A 20-cM region on 5q was physically and genetically mapped to obtain accurate marker order and intermarker distances. This locus on 5q12, which we have designated as "STRK1," does not correspond to known susceptibility loci for stroke or for its risk factors and represents the first mapping of a locus for common stroke.

Evaluation of the poly(ADP-ribose) polymerase gene in human stroke

Nitric oxide (NO) and its reactant product, peroxynitrite, have been implied to mediate neuronal damage following cerebral ischemia. However, the cellular targets of these compounds remain unclear. Studies using poly(ADP-ribose) polymerase (PARP) inhibitors and PARP knock-out mice have recently demonstrated that excessive activation of this nuclear enzyme plays an important role in NO-induced neurotoxicity. To evaluate the relevance of this plausible candidate gene to human stroke, we undertook a case-control study in Japanese. Participants comprised 213 cerebral infarction cases and 374 age- and sex-matched controls. As a primary investigation, we screened polymorphic sites of the PARP gene, and newly identified a total of four polymorphisms in 1230-bp 5'-flanking sequence. None of them were, however, located on the known promoter components of the gene. Two bi-allelic polymorphisms selected and a CA-repeat polymorphism were subsequently characterized in the case-control study, but none were significantly associated with cerebral infarction in the present study. Our data thus suggest that the tested PARP polymorphisms do not principally contribute to cerebral infarction, although extensive searches would be required to clarify whether the PARP gene plays an important role in the pathogenesis of human stroke.

Gene polymorphism of the renin-angiotensin system associates with risk for lacunar infarction. The Ohasama study

The polymorphism of the angiotensin-converting enzyme gene is considered to be associated with increased risk for stroke, but there is a diversity in the results obtained. The genetic involvement of the renin-angiotensin system in stroke also remains unclear. To predict the genetic risk of lacunar infarction, we conducted an association study in an Ohasama population, which is the cohort in a rural region of northern Japan. A total of 134 subjects without major neurological, cardiovascular, or metabolic disorders were recruited. Using brain magnetic resonance imaging, the number of lacunae in each of four brain regions were calculated, and periventricular hyperintensity was classified into five grades. We used the following four candidate gene polymorphisms: angiotensin converting enzyme (ACE)/Insertion(I)-Deletion(D), angiotensinogen (AGT)/M235T, angiotensin II type 1 receptor (AT1)/ A1166C, type 2 receptor (AT2)/C3123A, to examine the association between polymorphisms and the severity of lacunar infarction. AGT/M235T was significantly associated with the number of lacunae in the brain stem, the basal ganglia (P < .05), and whole brain (P < .005) regions. The AT1 polymorphism was also significantly associated with the number of lacunae in the basal ganglia and whole brain regions (P < .05), and with periventricular hyperintensity grade (P < .005) in the younger population. However, ACE and AT2 polymorphisms failed to show an association with either the number of lacunae or the PVH grade. We concluded that AGT and AT1 polymorphisms are independent genetic risk factors for lacunar infarction.

Do hemophilia A and von Willebrand disease protect against carotid atherosclerosis? A comparative study between coagulopathics and normal subjects by means of carotid echo-color Doppler scan

Atherosclerosis is a multifactorial disease caused by genetic and environmental factors with important clinical sequelae. The aim of this study was to evaluate the degree of carotid atherosclerosis by echo-color Doppler scan in a group of patients affected by hemophilia A and von Willebrand disease versus a group of normal subjects apparently free of atherosclerotic risk factors. All coagulopathics and normal patients who came to our Internal Medicine Department (Padua Hospital) underwent physical exam, blood analysis, standard electrocardiogram, chest x-ray, echo-color Doppler scan, and a thorough history. We examined 156 subjects, 76 coagulopathics (46 men, 30 women) and 77 normals (37 men, 40 women). Coagulopathics were affected by hypertension in 28.9% of cases, diabetes mellitus in 6.5%, dislipidemia in 17.1%, smoke in 39.4%, and obesity in 36.8% (p < .05). Echo-color Doppler scan revealed carotid plaques in 27.2% of control patients versus 13.1% of coagulopathics (p < .05). Hemophilics and subjects with von Willebrand disease with a more serious illness had fewer plaques than those with lighter defects. Coagulopathics showed 23.6% of the plaques we revealed on the whole, versus 76.3% of control subjects (p < .01), with a lighter degree of stenosis (p < .01). Our data demonstrate that patients with hemophilia A and von Willebrand disease have fewer carotid plaques and a smaller degree of carotid stenosis than normal subjects of the same sex and age. These data seem to strengthen the hypothesis that blood coagulation defects may allow protection against carotid atherosclerosis and its sequelae.

The 2 Gene Coding Sequence T807/A873 of the Platelet Collagen Receptor Integrin 2β1 Might Be a Genetic Risk Factor for the Development of Stroke in Younger Patients

The polymorphisms C807T and G873A of the platelet integrin 2β1 (collagen receptor glycoprotein [GP] Ia-IIa) are linked to the expression density of this receptor. The GPIa T807/A873 allele causes a higher receptor expression, enhancing platelet binding to collagen. This might present a genetic predisposition for the development of thromboembolic complications. In this case-control study, the genotypes of the GPIa C807T polymorphism and presence of conventional risk factors (hypertension, diabetes mellitus, and smoking) were compared in stroke patients and patients without cerebrovascular disease (non-CVD patients) ≤50 years of age (n = 45 and 41, respectively) and in stroke patients and non-CVD patients more than 50 years of age (n = 182 and 129, respectively. In patients ≤50 years of age, the T807 allele was the only overrepresented variable (P = .023; odds ratio, 3.02; 95% confidence interval, 1.20 to 7.61) and an independent risk factor, whereas the presence of conventional risk factors was similar between stroke patients ≤50 years of age and non-CVD patients ≤50 years of age. Large epidemiological studies should prove whether the platelet collagen receptor GPIa-IIa T807 allele is an independent risk factor for the development of stroke in younger patients.

The 2 Gene Coding Sequence T807/A873 of the Platelet Collagen Receptor Integrin 2β1 Might Be a Genetic Risk Factor for the Development of Stroke in Younger Patients

The polymorphisms C807T and G873A of the platelet integrin 2β1 (collagen receptor glycoprotein [GP] Ia-IIa) are linked to the expression density of this receptor. The GPIa T807/A873 allele causes a higher receptor expression, enhancing platelet binding to collagen. This might present a genetic predisposition for the development of thromboembolic complications. In this case-control study, the genotypes of the GPIa C807T polymorphism and presence of conventional risk factors (hypertension, diabetes mellitus, and smoking) were compared in stroke patients and patients without cerebrovascular disease (non-CVD patients) ≤50 years of age (n = 45 and 41, respectively) and in stroke patients and non-CVD patients more than 50 years of age (n = 182 and 129, respectively. In patients ≤50 years of age, the T807 allele was the only overrepresented variable (P = .023; odds ratio, 3.02; 95% confidence interval, 1.20 to 7.61) and an independent risk factor, whereas the presence of conventional risk factors was similar between stroke patients ≤50 years of age and non-CVD patients ≤50 years of age. Large epidemiological studies should prove whether the platelet collagen receptor GPIa-IIa T807 allele is an independent risk factor for the development of stroke in younger patients.

Genetic susceptibility and ischaemic stroke

In the past year the search for genetic susceptibility factors involved in ischaemic stroke has motivated a number of important studies in humans and animals. These have been focused on genetic susceptibility as a risk factor for ischaemic stroke, or as a determinant of ischaemic stroke outcome. Because there is increasing evidence that genetic factors play a role, it seems that epidemiological studies assessing both environmental and genetic risk factors may help to understand the cause of ischaemic stroke better. This may have therapeutic and preventive implications.

Genetics of stroke--a review

Evidence from twin and family shows that genetic factors contribute to the risk of stroke and that their role may be at least as important in stroke as in coronary heart disease. Additional support for the significance of genetic factors comes from other findings such as epidemiological data showing phenotypic heterogeneity of stroke, genetic influence on many of the risk factors for stroke, and racial and geographic differences in morbidity and mortality in stroke victims. Yet, apart from the reported associations of a small number of cases with Mendelian cerebrovascular diseases, only a few studies have directly investigated gene markers or molecular genetics of stroke. This review presents the existing evidence on the genetic background of stroke and discusses results from the genetic studies of stroke published to date.

Family history: a comprehensive genetic risk assessment method for the chronic conditions of adulthood

Targeting individuals with increased risk for common, chronic disease can improve the efficiency and efficacy of preventive efforts by improving the predictability of screening tests and participant compliance. Individuals with the greatest risk for these disorders are those with a genetic susceptibility. The purpose of this study was to determine the feasibility of using a single, comprehensive family history as a method for stratifying risk for many preventable, common genetic disorders. Family histories obtained in a prenatal diagnostic clinic were reviewed regarding cardiovascular diseases, diabetes and several cancers; 42.5% of individuals reported a family history for at least one of the disorders under study. Familial coronary artery disease was most commonly reported (29% of participants), followed by noninsulin-dependent diabetes (14%). Qualitative characterization of disease susceptibility was also accomplished using family history data. For example, occurrence of different cancers within pedigrees was suggestive of familial cancer syndromes, and clustering of noninsulin-dependent diabetes and cardiovascular disease suggested an insulin resistance syndrome. Depending on the specific disease, 5 to 15% of at-risk individuals had a moderately increased risk (2 to 5 times the population risk), and approximately 1 to 10% had a high risk (absolute risks approaching 50%). Family history reports of common, chronic disease are prevalent among the population at large, and collection and interpretation of comprehensive family history data is a feasible, initial method for risk stratification for many preventable, chronic conditions. These findings may have important implications for disease prevention and management.

Polymorphism of the angiotensin-converting enzyme (ACE) gene in patients with thrombotic brain infarction

The relationship between cerebrovascular disease and an insertion/deletion (I/D) polymorphism in intron 16 of the angiotensin-converting enzyme (ACE) gene is still being debated. We examined its role as a risk factor in patients with thrombotic brain infarction. The association between ACE polymorphism and ischemic stroke was examined in 181 patients with thrombotic brain infarction and 271 controls without strokes. The I/D polymorphism was examined using the polymerase chain reaction. Distributions of the ACE genotypes and alleles did not differ between the infarcted patients and the controls. Both distributions in patients with onset at age 60 years or younger were significantly higher than those in younger controls (genotype: chi 2 = 7.6, P = 0.02; allele: chi 2 = 5.6, P = 0.02). There were no significant differences in the distributions of ACE genotypes and alleles between the patients with lacunar infarcts and with cortical infarcts in all ages. There were also significant differences in the distribution of ACE genotypes and alleles between the younger and the elderly subgroup of patients with brain infarction (genotype: chi 2 = 12.9, P = 0.002; allele: chi 2 = 11.1, P = 0.0009). Furthermore, there was a significant decline in the frequency of the ACE D allele with increasing age in all patients with thrombotic brain infarction. These observations demonstrated a significant association between the ACE gene polymorphism and thrombotic brain infarction in patients age 60 years or younger in a Japanese population. Furthermore, there may be an association between the ACE D allele and mortality after cerebral infarction.

The genetics of dementia in late life

Recent advances in the genetics of AD and other late-life dementias have provided new insights but also have raised new queries and ethical issues. This review reflects the current state of knowledge in a rapidly evolving field. The complex relation of genes and environment to AD, VaD, and other late-life dementias suggests that the answers to these many issues will evolve through time. New issues undoubtedly will arise as additional genes are discovered and new data accrue that relate APOE and other genes to the mechanism and expression of dementing illness. The clinical relevance and applicability of such research findings will increase when effective treatments become available. Given this potential, we encourage readers to monitor new developments as they arise.

Is family history an independent risk factor for stroke?

OBJECTIVE

To estimate the influence of family history on the occurrence of stroke.

METHODS

A case-control study was carried out from August 1992 to January 1994. The study population comprised 502 patients with a first stroke, aged between 20 and 70 years, who were treated at 48 affiliated hospitals. The same number of age and sex matched controls were selected from outpatients. Diagnoses were based on CT findings and clinical signs. There were 155 case-control pairs for subarachnoid haemorrhage, 158 for intracerebral haematoma, and 159 for cerebral infarction. Information about the patients and their families was obtained from a questionnaire which included the family histories of each subtype of stroke and other potential risk factors for stroke. The data were analysed focusing on the role of the family histories in the occurrence of stroke.

RESULTS

In univariate analysis, the family histories of subarachnoid haemorrhage and intracerebral haematoma were positively associated with each of the subtypes of stroke (odds ratios 11.24 for subarachnoid haemorrhage, 2.39 for intracerebral haematoma), whereas family history of cerebral infarction was not a significant risk factor for its occurrence (odds ratio 1.41). Family history of intracerebral haematoma was correlated with a personal history of hypertension and habitual alcohol consumption. After adjustment for potential risk factors (hypertension, diabetes, hyperlipidaemia, obesity, alcohol consumption, and regular smoking), family history of subarachnoid haemorrhage still remained the most powerful risk factor for subarachnoid haemorrhage, whereas family history of intracerebral haematoma no longer showed a significant association with haematoma.

CONCLUSION

Genetic factors play a major part in the pathogenesis of subarachnoid haemorrhage, and family history of subarachnoid haemorrhage is the strongest independent risk factor for the disease. On the other hand, family history of intracerebral haematoma was not an independent risk factor for haematoma, but it might be a good predictor, which indirectly influences the pathogenesis of intracerebral haematoma via certain hereditary components such as hypertension, and even lifestyle factors such as alcohol consumption. In cerebral infarction, genetic factors play a minor part in its pathogenesis.

Recent advances in the genetics of Alzheimer's disease and vascular dementia with an emphasis on gene-environment interactions

OBJECTIVE

To review recent findings in the genetics of Alzheimer's disease (AD) and vascular dementia (VaD) with particular emphasis on gene-environment interactions.

DESIGN

A survey and critique of recent literature on the genetic etiology of AD and VaD.

CONCLUSIONS

Recent research has identified several genes associated with AD, including loci on chromosome 1, 14, 19, and 21. Two of these loci, encoding the beta-amyloid precursor protein and apolipoprotein E, have gene products that are well characterized and of evident significance in the pathogenesis of AD. The four genes together probably account for little more than 50% of all cases of AD, but other undiscovered loci are likely. Interaction of genetic effects with environmental influences may affect both onset and expression of AD. By contrast, only a small minority of VaD cases can be attributed to a pure genetic etiology. The majority of VaD is caused by both genetic and environmental factors. Many of the environmental antecedents also have genetic determinants (e.g., smoking). Knowledge of the gene-environment interactions for both AD and VaD will facilitate identification of early preclinical symptoms of disease, a stage of the disease process during which treatment may be most beneficial.

Inappropriate use of bivariable analysis to screen risk factors for use in multivariable analysis

The use of bivariable selection (BVS) for selecting variables to be used in multivariable analysis is inappropriate despite its common usage in medical sciences. In BVS, if the statistical p value of a risk factor in bivariable analysis is greater than an arbitrary value (often p = 0.05), then this factor will not be allowed to compete for inclusion in multivariable analysis. This type of variable selection is inappropriate because the BVS method wrongly rejects potentially important variables when the relationship between an outcome and a risk factor is confounded by any confounder and when this confounder is not properly controlled. This article uses both hypothetical and actual data to show how a nonsignificant risk factor in bivariable analysis may actually be a significant risk factor in multivariable analysis if confounding is properly controlled. Furthermore, problems resulting from the automated forward and stepwise modeling with or without the presence of confounding are also addressed. To avoid these improper procedures and deficiencies, alternatives in performing multivariable analysis, including advantages and disadvantages of the BVS method and automated stepwise modeling, are reviewed and discussed.