Disease In African Americans Research Articles

Genetic variation in apolipoprotein D affects the risk of Alzheimer disease in African-Americans.

Apolipoprotein D (APOD, gene; apoD, protein) is involved in neuroregenerative and neurodegenerative processes, and is upregulated in late-onset Alzheimer disease (AD) patients compared to nondemented controls. No genetic association studies have yet been carried out to investigate the role of APOD in AD. We have reported recently several sequence variants in the APOD gene, which are present exclusively among African blacks. In the present study we examined the role of four APOD genetic variants (Intron 1, codons 36, 108, 158) in modifying the risk of AD in 70 subjects with AD and 163 nondemented subjects from a population-based African-American cohort in Indianapolis. The Intron 1*2 allele was associated with an increased AD risk with an age, gender and APOE adjusted odds ratio (OR) of 2.29 (95% confidence interval [CI]: 1.19-4.43; P = 0.013), and this risk was confined to APOE*4 carriers (OR 3.12; 95% CI: 1.13-8.60; P = 0.028). The frequency of the codon 36/GT genotype was non-significantly higher in individuals with AD than nondemented subjects (4.3% vs. 1.2%) with an adjusted OR of 4.24 (95% CI: 0.66-27.14; P = 0.13). Our data suggest that the risk of AD among African-Americans may be modified by genetic variation in APOD. Larger population-based or case-control studies are needed to confirm the role of APOD genetic variation in AD.

Cancer statistics for African Americans.

The American Cancer Society provides estimates on the number of new cancer cases and deaths, and compiles health statistics on African Americans in a biennial publication, Cancer Facts and Figures for African Americans. The compiled statistics include cancer incidence, mortality, survival, and lifestyle behaviors using the most recent data on incidence and survival from the National Cancer Institute's (NCI) Surveillance, Epidemiology, and End Results (SEER) program, mortality data from the National Center for Health Statistics (NCHS), and behavioral information from the Behavior Risk Factor Surveillance System (BRFSS), Youth Risk Behavior Surveillance System (YRBSS), and National Health Interview Survey (NHIS). It is estimated that 132,700 new cases of cancer and 63,100 deaths will occur among African Americans in the year 2003. Although African Americans have experienced higher incidence and mortality rates of cancer than whites for many years, incidence rates have declined by 2.7 percent per year in African-American males since 1992, while stabilizing in African-American females. During the same period, death rates declined by 2.1 percent and 0.4 percent per year among African-American males and females, respectively. The decrease in both incidence and death rates from cancer among African-American males was the largest of any racial or ethnic group. Nonetheless, African Americans still carry the highest cancer burden among US racial and ethnic groups. Most cancers detectable by screening are diagnosed at a later stage and survival rates are lower within each stage of disease in African Americans than in whites. The extent to which these disparities reflect unequal access to health care versus other factors is an active area of research.

Hypertension-related disease in African Americans

PREVIEWAfrican Americans have a higher prevalence of hypertension, diabetes, cardiovascular disease (CVD), stroke, and renal disease than white Americans. The high rates of diabetes and hypertension in children and of type 2 diabetes, stroke, and CVD in women are particularly striking. In this article, Drs Sowers, Ferdinand, Bakris, and Douglas examine the biologic, social, and genetic factors that contribute to these health disparities, the risk for which appears in early childhood.

Traditional and Non-Traditional Risk Factors for Cardiovascular and Renal Disease in African Americans: A Project of the Jackson Heart Study Investigators

Advances in the diagnosis and management of cardiovascular disease (CVD) have resulted in a decrease in cardiovascular mortality over the last 2 to 3 decades. However, despite these advances, African Americans continue to shoulder a disproportionate share of the CVD burden in the United States. There are several hypotheses for this discrepancy, yet few have been rigorously studied. These include poorer access to healthcare; increased incidence of CVD risk factors such as hypertension, diabetes, and obesity; and, possibly, genetic influences. The Jackson Heart Study (JHS) is focused on identifying the reasons for this racial disparity in CVD.

Association of the tissue kallikrein gene promoter with ESRD and hypertension

Kallikreins have long been implicated in human essential hypertension and associated complications. In particular, low urinary kallikrein excretion has been associated with hypertension and renal disease in African Americans. In an effort to identify the source of differential kallikrein excretion, we investigated the promoter of KLK1, the tissue kallikrein gene. The KLK1 promoter is uniquely polymorphic with a poly-G length polymorphism coupled with multiple single base substitutions. In this report, we genetically evaluated the association of KLK1 gene promoter alleles with end-stage renal disease (ESRD) in African Americans. A total of 15 haplotypes were identified in the KLK1 promoter region through detailed DNA sequence analysis. This polymorphic region was then genetically evaluated for association with ESRD in African Americans with diabetic and non-diabetic etiologies of ESRD. The complex polymorphic nature of the promoter presents challenges to determining the alleles. We have redefined the region as six separate loci: five substitution loci and one length locus. The length locus was defined as G repeats starting at position -130 and ending at -121 on the gene. Among four relevant substitution loci for this study, one at position -131, just outside the G repeats, is an A-to-G substitution. The other three variant positions are -129, -128, and -127, all G-to-C substitutions within the G repeats. This region was genotyped in African American subjects with and without ESRD using semiautomated sequencing. Four different G repeat alleles ranging from 11.8% for 12 Gs to 52.3% for 10 Gs were observed in 86 control subjects. The C substitution of Gs ranges from 2.9% at position -127 to 8.2% at -129. When affected probands from each of 76 hypertensive ESRD families were genotyped, an association for the 12 G allele, the longest of the length locus alleles, was detected (allele specific P = 0.004 and locus total P = 0.02). When all ESRD affected individuals with hypertension from each family (107 patients in total) were used in the analysis, an even stronger association was observed for this allele (allele specific P = 0.003, locus total P = 0.01). This allele was more frequent in the hypertensive (non-diabetic) patients (0.20 in probands and 0.19 in all ESRD cases) than in the controls (0.12). No evidence of association in diabetic ESRD patients was observed (P = 0.93). The KLK1 promoter is uniquely polymorphic. The observed genetic association suggests an etiologic effect of the KLK1 promoter on hypertension and/or hypertension associated ESRD.

Diabetic Renal Disease in African Americans

Diabetic nephropathy (DN) is the No. 1 cause of end-stage renal disease in the United States and is highly prevalent in African Americans. Almost all DN in African Americans is caused by type 2 diabetes. Glycemic control and control of blood pressure are essential to prolong renal survival and to protect against cardiovascular events. Among African Americans, diabetic nephropathy seems to affect women more than men, which may be related to increased rates of obesity and diabetes in African American women. In addition to gender, the development of albuminuria, family history, and possibly birth weight are factors that predict progression of renal disease in African Americans with DN. The impact of glycemic control, appropriate antihypertensives, and the optimal level of blood pressure control in African Americans with advanced DN require further study. This article will review the clinical characteristics, risk factors, predictors of disease progression, and treatment of diabetic nephropathy in African Americans.

The Epidemiology of End-Stage Renal Disease among African Americans

Although disparities in outcomes among African Americans compared with whites with respect to cardiovascular disease, cancer, diabetes, infant mortality, and other health standards have been well-described, these disparities are most dramatic with respect to kidney diseases. End-stage renal disease (ESRD) occurs almost 4 times more commonly in African Americans than in their white counterparts. These disparate rates of kidney disease may be caused by the complex interplay of genetic, environmental, cultural, and socioeconomic factors. African Americans are particularly vulnerable to the deleterious renal effects of hypertension and may require more aggressive blood pressure control than whites to accrue benefit with respect to preservation of renal function. Diabetes, the leading cause of ESRD in the United States, is another important factor in the excess renal morbidity and mortality of African Americans because of its prevalence in this population. Other renal diseases, especially those associated with HIV/AIDS, are also much more likely to affect African Americans than other American population subgroups. A more thorough understanding of the epidemiology of renal diseases in African Americans and the cultural, social, and biological differences that underlie racial disparities in prevalence of renal disease will be essential to the design of effective public health strategies for prevention and treatment of this burdensome problem.

The association between hypertension and other cardiovascular risk factors in young adult African Americans.

Hypertension is a major cause of cardiovascular disease in African Americans. The excess morbidity and mortality due to cardiovascular disease in African Americans compared to Caucasians is not well explained. The purpose of this study was to examine the association between hypertension and other cardiovascular risk factors in young adult African Americans. A risk factor scoring system was developed, based on national guidelines for obesity, smoking, cholesterol levels, glucose tolerance, and blood pressure. Data from a previously studied cohort of 206 women and 117 men were analyzed for the association of hypertension with other risk factors. Among women, risk factor intensification is due to impaired glucose tolerance and obesity. Among men, intensification appears to be related to all major risk factor categories. These findings indicate that among hypertensive African Americans there is an amplification of other risk factors. The data also support the clinical management of multiple risk factors as well as the achievement of blood pressure control.

Autoimmune hepatitis in African Americans: presenting features and response to therapy

OBJECTIVES: African Americans are at an increased risk for certain diseases and more frequently suffer complications of those diseases relative to their white counterparts. Most studies of autoimmune hepatitis consist of entirely white populations. The Emory University system of hospitals serves a large African American population, including a significant number of African Americans with autoimmune hepatitis. The goal of this study was to determine if the presentation and response to therapy in African Americans is, like other diseases, different than in whites. METHODS: This is a retrospective study from a tertiary referral center that examines the initial presenting features and response to therapy of African Americans (n = 27) and whites (n = 24) with autoimmune hepatitis. RESULTS: Eighty-five percent of African Americans had cirrhosis on the initial liver biopsy, as compared with 38% of whites. Although not statistically significant, the African Americans presented at an earlier age than white patients. The disease also appeared more advanced in African Americans, as bilibubin levels tended to be higher, but not significantly, and PTs were more prolonged. Both groups responded well to therapy, with significant falls in serum levels of AST, ALT, and bilirubin. Fifty percent of African Americans and 48% of whites entered a biochemical remission. The amount of prednisone required to maintain remission at follow-up was greater in African Americans. CONCLUSION: In contrast to whites, the majority of African Americans present with cirrhosis. Despite the high prevalence of cirrhosis, the response to therapy is good. However, more immunosuppression is required to control the disease in African Americans.

Autoimmune hepatitis in African Americans: presenting features and response to therapy.

African Americans are at an increased risk for certain diseases and more frequently suffer complications of those diseases relative to their white counterparts. Most studies of autoimmune hepatitis consist of entirely white populations. The Emory University system of hospitals serves a large African American population, including a significant number of African Americans with autoimmune hepatitis. The goal of this study was to determine if the presentation and response to therapy in African Americans is, like other diseases, different than in whites. This is a retrospective study from a tertiary referral center that examines the initial presenting features and response to therapy of African Americans (n = 27) and whites (n = 24) with autoimmune hepatitis. Eighty-five percent of African Americans had cirrhosis on the initial liver biopsy, as compared with 38% of whites. Although not statistically significant, the African Americans presented at an earlier age than white patients. The disease also appeared more advanced in African Americans, as bilibubin levels tended to be higher, but not significantly, and PTs were more prolonged. Both groups responded well to therapy, with significant falls in serum levels of AST, ALT, and bilirubin. Fifty percent of African Americans and 48% of whites entered a biochemical remission. The amount of prednisone required to maintain remission at follow-up was greater in African Americans. In contrast to whites, the majority of African Americans present with cirrhosis. Despite the high prevalence of cirrhosis, the response to therapy is good. However, more immunosuppression is required to control the disease in African Americans.

White blood cell count and incidence of coronary heart disease and ischemic stroke and mortality from cardiovascular disease in African-American and White men and women: atherosclerosis risk in communities study.

The authors examined the association between white blood cell (WBC) count and incidence of coronary heart disease and ischemic stroke and mortality from cardiovascular disease in 13,555 African-American and White men and women from the Atherosclerosis Risk in Communities (ARIC) Study. Blood was drawn at the ARIC baseline examination, beginning in 1987-1989. During an average of 8 years of follow-up (through December 1996), there were 488 incident coronary heart disease events, 220 incident strokes, and 258 deaths from cardiovascular disease. After adjustment for age, sex, ARIC field center, and multiple risk factors, there was a direct association between WBC count and incidence of coronary heart disease (p < 0.001 for trend) and stroke (p for trend < 0.001) and mortality from cardiovascular disease (p for trend < 0.001) in African Americans. The African Americans in the highest quartile of WBC count (> or =7,000 cells/mm(3)) had 1.9 times the risk of incident coronary heart disease (95% confidence interval (CI): 1.19, 3.09), 1.9 times the risk of incident ischemic stroke (95% CI: 1.03, 3.34), and 2.3 times the risk of cardiovascular disease mortality (95% CI: 1.38, 3.72) as their counterparts in the lowest quartile of WBC count (<4,800 cells/mm(3)). These associations were similar in Whites and in never smokers. An elevated WBC count is directly associated with increased incidence of coronary heart disease and ischemic stroke and mortality from cardiovascular disease in African-American and White men and women.

Racism and tPA Use in African-Americans

To the Editor: The investigation of Johnston et al1 into the influence of ethnicity on thrombolysis raises the spectre of racism in health service provision. However, as shown in the case of cardiac catheterization after myocardial infarction, racism is not always the reason for differences in treatment.2 Although the authors used a simple dichotomous definition of stroke severity in their regression analysis, they did not account for stroke subtype (or National Institutes of Health Stroke Scale [NIHSS] score). The proportion of ischemic stroke due to small-vessel disease in African-Americans is 52% compared with 25% in whites.3 Lacunar strokes tend to be less severe (maximum NIHSS of 10) and have a better prognosis than cortical ischemic strokes.4 The authors’ Table 2 demonstrates that despite American Heart Association guidelines, physicians are reluctant to give tPA to patients with …

Health status of African Americans.

The health status of African Americans identifies a higher prevalence of cardiovascular diseases, cancer, hypertension, diabetes, obesity, and sexually transmitted infections when compared with Whites. However, more research is needed to identify socioeconomic variables and to establish needed health programs. The vestiges of early 20th century traditions of substandard housing and inadequate nutrition for African Americans are still apparent in many communities today. Most health care professionals are not educated and trained to be culturally sensitive. The struggle against the prevalence of diseases in African Americans must incorporate cultural sensitivity, community organization and empowerment. The need for a universal system of health insurance coverage is of utmost importance. The elimination of health disparities among African Americans requires a national effort, the involvement of public and private sectors, individuals and communities.

Melanoma in African-Americans: trends in biological behavior and clinical characteristics over two decades.

The incidence of melanoma in the United States is increasing. Data on this disease in African-Americans is sparse. Chart review of patients diagnozed with melanoma from 1975 to 1997 at Charity Hospital New Orleans (CHNO). Age, gender, anatomic distribution, histology, presenting stage, survival, and race were evaluated. Forty-four of 198 patients were African-American, of whom the majority developed cutaneous melanoma on the acral surface of the foot. African-American males were four times more likely to present with a cutaneous lesion than were African-American females. The median survival time for African-American with cutaneous lesions was 45 months, compared to 135 months for caucasians who were 3.6 times more likely to present with early disease (P < 0.05). TNM stage at presentation, and ulceration were significant, independent factors associated with a worse outcome in African-Americans. Overall survival time for African-Americans with cutaneous melanoma is significantly shorter than for caucasians with this disease. This trend may be attributable to the fact that African-Americans present with advanced disease. An increased level of awareness among both patients and health-care providers is necessary to identify African-Americans with melanoma at earlier stages of disease and to improve survival.

Minority Health a focus of recent NIH budget increases

Improved funding aimed at eliminating health disparities among minorities including African Americans, Asian Americans, Hispanics and Native Americans part of the recently announced NIH funding increases. As reported by Tom Hollon (www.the-scientist.com), the newly established National Center for Research on Minority Health and Health Disparities will try to tackle issues such as the racial differences that exist in interferon treatments for chronic hepatitis C, and the disproportionately high rates of autoimmune disease in African Americans. Replacing the old Office of Research on Minority Health, the new centre is just one of the new initiatives forming part of the US$2.5 billion increase in NIH funding. Total government funding for medical research in the USA will reach US$20.3 billion for fiscal year 2001. SHK

Coronary heart disease in African Americans.

African Americans have the highest overall mortality rate from coronary heart disease (CHD) of any ethnic group in the United States, particularly out-of-hospital deaths, and especially at younger ages. Although all of the reasons for the excess CHD mortality among African Americans have not been elucidated, it is clear that there is a high prevalence of certain coronary risk factors, delay in the recognition and treatment of high-risk individuals, and limited access to cardiovascular care. The clinical spectrum of acute and chronic CHD in African Americans is similar to that in whites. However, African Americans have a higher risk of sudden cardiac death and present more often with unstable angina and non-Q-wave myocardial infarction than whites. African Americans have less obstructive coronary artery disease on angiography, but may have a similar or greater total burden of coronary atherosclerosis. Ethnic differences in the clinical manifestations of CHD may be explained largely by the inherent heterogeneity of the coronary syndromes, and the disproportionately high prevalence and severity of hypertension and type 2 diabetes in African Americans. Identification of high-risk individuals for vigorous risk factor modification-especially control of hypertension, regression of left ventricular hypertrophy, control of diabetes, treatment of dyslipidemia, and smoking cessation--is key for successful risk reduction.

Hypertensive kidney disease in African Americans

SUMMARY:End‐stage renal disease is a significant public health problem in both developed and developing countries. The magnitude and pattern of renal disease varies between countries. This variability could probably be explained by the racial and ethnic composition. The United States is a typical example, showing significant racial and ethnic differences in the magnitude and pattern of renal disease. African Americans, Native Americans and Pacific Islanders are disproportionately afflicted with end‐stage kidney failure (ESRD), compared with Caucasians and Asians. Whereas diabetes mellitus, primarily type 2, is the predominant cause of renal disease (and ESRD) in the US, and prominently in Native Americans, hypertensive kidney disease is the most prevalent cause of ESRD in African Americans. Some of the suggested reasons for the increased incidence and prevalence of hypertensive kidney disease in African Americans include the higher prevalence and severity of hypertension, especially in the early years of life, lower socio‐economic status leading to inadequate health care, a greater propensity towards developing intrinsic renal vascular disease, a greater tendency towards developing target organ damage at ‘normal’ blood pressure levels, and the use of drugs that are less renoprotective to treat their blood pressure.

Behavioral Treatment of Hypertensive Heart Disease in African Americans: Rationale and Design of a Randomized Controlled Trial

African Americans experience higher morbidity and mortality than Whites do as a result of hypertension and associated cardiovascular disease. Chronic psychosocial stress has been considered an important contributing factor to these high rates. The authors describe the rationale and design for a planned randomized controlled trial comparing Transcendental Meditation, a stress-reduction technique, with lifestyle education in the treatment of hypertension and hypertensive heart disease in urban African Americans. They pretested 170 men and women aged 20 to 70 years over a 3-session baseline period, with posttests at 6 months. Outcomes included clinic and ambulatory blood pressure, quality of life, left ventricular mass measured by M-mode echocardiography, left ventricular diastolic function measured by Doppler, and carotid atherosclerosis measured by β-mode ultrasound. This trial was designed to evaluate the hypothesis that a selected stress reduction technique is effective in reducing hypertension and hypertensive heart disease in African Americans.

Low birth weight contributes to the excess prevalence of end-stage renal disease in African Americans.

The risk of hypertension and related target organ damage is much greater in African Americans than in Caucasians. The risk of hypertensive end-stage renal disease is approximately five-fold higher in African Americans. Many studies have shown that low birth weight is strongly associated with increased risk of hypertension, stroke, and myocardial infarction. However, until recently the relationship between birth weight and hypertension-related diseases was not clearly established in African Americans. Moreover, it was also unclear if low birth weight in humans heightened the risk for end-stage renal disease. This is a critical gap in the literature, since low birth weight occurs at twice the rate in African Americans as among Caucasians. We identified a significant relationship between end-stage renal disease and low birth weight in both African Americans and Caucasians. Given the higher rates of low birth weight in African Americans, differences in fetal development may, therefore, contribute to the racial disparity in end-stage renal disease. Continued study of the biological factors linking early development with later risk of hypertension-related diseases is important and may shed light on racial disparities in health outcomes. (c)2001 by Le Jacq Communications, Inc.

Salivary mucin: a factor in the lower prevalence of gastroesophageal reflux disease in African-Americans?

OBJECTIVES: Organic and inorganic constituents of saliva have been implicated as protective components in the esophagus, and deficiencies in one or more of these factors in different races may be an important element in the prevalence of gastroesophageal reflux disease (GERD). To determine whether there are differences in the concentration of salivary mucins between different racial groups, we measured the concentration of mucous glycoprotein MG1 and mucous glycoprotein MG2 in whole saliva of African-Americans and Caucasians. METHODS: Whole saliva was collected from 19 African-American (four male, 15 female; mean age 34 yr, range 19–53 yr, ) and 25 Caucasian (11 male, 14 female; mean age 31 yr, range 20–51 yr, ) volunteers under masticatory stimulation (1 g Parafilm, 60 strokes/min) between 11:00 AM and 12:00 noon. Total salivary carbohydrate was measured with a periodic acid-Schiff assay and total protein by absorbance at 215 nm. Immunological reagents were employed to quantify MG2 in a combined enzyme-linked immunosorbent assay/enzyme linked lectin assay (ELISA/ELLA) and to quantify MG1 in a capture ELISA. RESULTS: The total carbohydrate, protein, MG1 and MG2 values were 24.4 ± 11.9, 243.5 ± 62.7, 21.8 ± 13.4, and 11.6 ± 9.5 mg% for African-Americans, and the corresponding values were 23.3 ± 9.3, 221.7 ± 39.7, 25.7 ± 16.2, and 10.9 ± 8.7 mg% for Caucasians. There was no statistical difference for any of the parameters measured between the two groups. Furthermore, it was shown that no correlation existed between salivary flow rate and the concentration of carbohydrate, protein, or salivary mucins in African-Americans and in Caucasians. These results show that flow rate did not influence the measured values for salivary parameters in the two groups. CONCLUSIONS: No differences were found in the concentration of salivary mucins MG1 and MG2 in whole saliva of African-Americans and Caucasians, and it seems unlikely that variations in mucin levels influence the prevalence of GERD in these groups.