Association of hypothyroidism with low-level arsenic exposure in rural West Texas.

It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2-22µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8µg/L in 36% of the subjects' wells while iodine concentration was <1µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas.

Comparison of the accuracy of kriging and IDW interpolations in estimating groundwater arsenic concentrations in Texas.

Exposure to arsenic causes many diseases. Most Americans in rural areas use groundwater for drinking, which may contain arsenic above the currently allowable level, 10µg/L. It is cost-effective to estimate groundwater arsenic levels based on data from wells with known arsenic concentrations. We compared the accuracy of several commonly used interpolation methods in estimating arsenic concentrations in >8000 wells in Texas by the leave-one-out-cross-validation technique. Correlation coefficient between measured and estimated arsenic levels was greater with inverse distance weighted (IDW) than kriging Gaussian, kriging spherical or cokriging interpolations when analyzing data from wells in the entire Texas (p<0.0001). Correlation coefficient was significantly lower with cokriging than any other methods (p<0.006) for wells in Texas, east Texas or the Edwards aquifer. Correlation coefficient was significantly greater for wells in southwestern Texas Panhandle than in east Texas, and was higher for wells in Ogallala aquifer than in Edwards aquifer (p<0.0001) regardless of interpolation methods. In regression analysis, the best models are when well depth and/or elevation were entered into the model as covariates regardless of area/aquifer or interpolation methods, and models with IDW are better than kriging in any area/aquifer. In conclusion, the accuracy in estimating groundwater arsenic level depends on both interpolation methods and wells' geographic distributions and characteristics in Texas. Taking well depth and elevation into regression analysis as covariates significantly increases the accuracy in estimating groundwater arsenic level in Texas with IDW in particular.

Arsenic exposure, AS3MT polymorphism, and neuropsychological functioning among rural dwelling adults and elders: a cross-sectional study.

BACKGROUND: The aim was to examine the link between low-level arsenic exposure and cognitive functioning, and the potential role of a single nucleotide polymorphism (SNP A35991G, rs10748835) of the AS3MT gene in modifying this link. METHODS: Data were analyzed on 526 participants from Project FRONTIER. Hierarchical linear regressions were created with neuropsychological raw index scores as the outcome variable and arsenic exposure and AS3MT SNP as different predictor variables. RESULTS: Within the total sample, arsenic exposure was negatively associated with language (p < 0.001) and executive functioning (p < 0.001). Among those with the AA genotype of the AS3MT gene, arsenic levels were negatively associated with language (p < 0.001), attention (p = 0.01), and executive functioning (p = 0.04). Among those with the AG genotype, arsenic levels were positively associated with immediate (p = 0.04) and delayed memory (p < 0.001) and negatively associated with executive functioning (p = 0.03). Among those with the GG genotype, arsenic levels were negatively associated with visuospatial functioning (p = 0.02). CONCLUSIONS: Low-level arsenic exposure is associated with cognitive functioning; however, this association is modified by an AS3MT gene.

Socioeconomic deprivation as a determinant of cancer mortality and the Hispanic paradox in Texas, USA.

INTRODUCTION: We have recently reported that delayed cancer detection is associated with the Wellbeing Index (WI) for socioeconomic deprivation, lack of health insurance, physician shortage, and Hispanic ethnicity. The current study investigates whether these factors are determinants of cancer mortality in Texas, the United States of America (USA). METHODS: Data for breast, colorectal, female genital system, lung, prostate, and all-type cancers are obtained from the Texas Cancer Registry. A weighted regression model for non-Hispanic whites, Hispanics, and African Americans is used with age-adjusted mortality (2004-2008 data combined) for each county as the dependent variable while independent variables include WI, percentage of the uninsured, and physician supply. RESULTS: Higher mortality for breast, female genital system, lung, and all-type cancers is associated with higher WI among non-Hispanic whites and/or African Americans but with lower WI in Hispanics after adjusting for physician supply and percentage of the uninsured. Mortality for all the cancers studied is in the following order from high to low: African Americans, non-Hispanic whites, and Hispanics. Lung cancer mortality is particularly low in Hispanics, which is only 35% of African Americans' mortality and 40% of non-Hispanic whites' mortality. CONCLUSIONS: Higher degree of socioeconomic deprivation is associated with higher mortality of several cancers among non-Hispanic whites and African Americans, but with lower mortality among Hispanics in Texas. Also, mortality rates of all these cancers studied are the lowest in Hispanics. Further investigations are needed to better understand the mechanisms of the Hispanic Paradox.

Determinants of delayed detection of cancers in Texas counties in the United States of America.

INTRODUCTION: Previous studies have shown that delayed detection of several cancers is related to socioeconomic deprivation as measured by the Wellbeing Index (WI) in Texas, the United States of America (USA). The current study investigates whether delayed cancer detection is related to lack of health insurance, physician shortage and higher percentages of Hispanics rather than WI per se since these factors are directly related to delayed cancer detection and may confound WI. METHODS: Cancer data and potential determinants of delayed cancer detection are derived from Texas Cancer Registry, Texas State Data Center, and Texas Department of State Health Services and U.S. Census Bureau. Texas cancer data from 1997 to 2003 are aggregated to calculate age-adjusted late- and early-stage cancer detection rates. The WI for each county is computed using data from the USA Census 2000. A weighted Tobit regression model is used to account for population size and censoring. The percentage of late-stage cancer cases is the dependent variable while independent variables include WI and the aforementioned potential confounders. RESULTS: Delayed detection of breast, lung, colorectal and female genital cancers is associated with higher percentage of uninsured residents (p < 0.05). Delayed detection is also associated with physician shortage and lower percentages of Hispanics for certain cancers ceteris paribus ( p < 0.05). The percentage of late-stage cases is positively correlated with WI for lung, and prostate cancers after adjusting for confounders ( p < 0.05). CONCLUSIONS: The percentages of uninsured and Hispanic residents as well as physician supply are determinants of delayed detection for several cancers independently of WI, and vice versa. Identification of these determinants provides the evidence-base critical for decision makers to address specific issues for promoting early detection in effective cancer control.

Low-level arsenic exposure, AS3MT gene polymorphism and cardiovascular diseases in rural Texas counties.

Most Americans living in rural areas use groundwater for drinking. Exposure to low-level (around the current U.S. standard 10 µg/L) arsenic in drinking water is associated with increased mortality of cardiovascular diseases. The current study was to determine if coronary heart disease, hypertension, and hyperlipidemia were associated with low-level arsenic exposure and AS3MT gene single nucleotide polymorphism (SNP) A35991G (rs10748835) in rural Texas. Subjects (156 men, 343 women, 40-96 years of age with a mean of 61) were residents from rural counties Cochran, Palmer, and Bailey, Texas. Groundwater arsenic concentration at each subject's home was estimated with ArcGIS inverse distance weighted interpolation based on the residential location's distances to surrounding wells with known water arsenic concentrations. The estimated groundwater arsenic concentration ranged from 2.2 to 15.3 (mean 6.2) µg/L in this cohort. Logistic regression analysis showed that coronary heart disease was associated with higher arsenic exposure (p<0.05) and with AS3MT genotype GG vs. AA (p<0.05) after adjustments for age, ethnicity, gender, education, smoking status, alcoholism, and anti-hyperlipidemia medication. Hypertension was associated with higher arsenic exposure, while hyperlipidemia was associated with genotype AG vs. AA of the AS3MT gene (p<0.05). Thus, coronary heart disease and its main risk factors were associated with low-level arsenic exposure, AS3MT polymorphism or both.

Correlation of the ratio of metastatic to non-metastatic cancer cases with the degree of socioeconomic deprivation among Texas counties.

BACKGROUND: Previous studies have demonstrated that cancer registrations and hospital discharge rate are closely correlated with census data-based socioeconomic deprivation indices. We hypothesized that communities with higher degrees of socioeconomic deprivation tend to have a higher ratio of metastatic to non-metastatic cancer cases (lung, breast, prostate, female genital system, colorectal cancers or all types of cancers combined). In this study, we investigate the potential link between this ratio and the Wellbeing Index (WI) among Texas counties. RESULTS: Cancer data in 2000 were provided by the Texas Cancer Registry, while data on the ten socioeconomic variables among the 254 Texas counties in 2000 for building the WI were obtained from U.S. Census Bureau. The ten socioeconomic status variables were subjected to the principal component analysis, and the first principal component scores were grouped into deciles for the WI (1 to 10) and the 254 Texas counties were classified into 10 corresponding groups. Weighted linear regression analyses and a Cochran-Armitage trend test were performed to determine the relationship between the ratio of age-adjusted metastatic to non-metastatic cancer incidence cases and WI. The ratios of metastatic to non-metastatic cases of female genital system cancer (r2 = 0.84, p = 0.0002), all-type cancers (r2= 0.73, p = 0.0017) and lung cancer (r2= 0.54, p = 0.0156) at diagnosis were positively correlated with WI. CONCLUSIONS: The ratios of metastatic to non-metastatic cases of all-type, female genital system and lung cancers at diagnosis were statistically correlated with socioeconomic deprivation. Potential mediators for the correlation warrant further investigation in order to reduce health disparities associated with socioeconomic inequality.

Low-level groundwater arsenic exposure impacts cognition: a project FRONTIER study.

Arsenic is a ubiquitous environmental toxin with known neurological consequences. Few studies, however, have investigated groundwater arsenic concentrations and cognition among adults and elders. In the study described in this article, the authors examined the potential link between cognitive functioning and low concentrations of arsenic in drinking water. Arsenic concentrations were estimated by the Geographic Information System approach (GIS-arsenic) for 299 rural-dwelling adults and elders. Cognition was assessed with Folstein Mini-Mental State Examination (MMSE). Those in the relatively high GIS-arsenic exposure (> 10.0 microg/L) group had significantly lower MMSE scores than those in the low GIS-arsenic exposure (< or = 10.0 microg/L) group (p < .03). The number of years of education was significantly lower in those in the high GIS-arsenic group(s) than in those in the low GIS-arsenic group (p < .05). These results suggest that poorer cognitive functioning and lower education levels were associated with higher (though still low-level) GIS-arsenic levels in this rural adult cohort.

The arsenic exposure hypothesis for Alzheimer disease.

Prior research has shown that arsenic exposure induces changes that coincide with most of the developmental, biochemical, pathologic, and clinical features of Alzheimer disease (AD) and associated disorders. On the basis of this literature, we propose the Arsenic Exposure Hypothesis for AD that is inclusive of and cooperative with the existing hypotheses. Arsenic toxicity induces hyperphosphorylation of protein tau and overtranscription of the amyloid precursor protein, which are involved in the formation of neurofibrillary tangles and brain amyloid plaques, consistent with the amyloid hypothesis of AD. Arsenic exposure has been associated with cardiovascular diseases and associated risk factors, which is in agreement with the vascular hypothesis of AD. Arsenic exposure invokes brain inflammatory responses, which resonates with the inflammatory hypotheses of AD. Arsenic exposure has been linked to reduced memory and intellectual abilities in children and adolescents, which provides a biologic basis for the developmental origin of health and disease hypothesis for AD. Arsenic and its metabolites generate free radicals causing oxidative stress and neuronal death, which fits the existing oxidative stress hypothesis. Taken together, the arsenic exposure hypothesis for AD provides a parsimonious testable hypothesis for the development and progression of this devastating disease at least for some subsets of individuals.

Family information service participation increases the rates of mutation testing among members of families with BRCA1/2 mutations.

Some members of hereditary breast-ovarian cancer (HBOC) families may not participate in BRCA testing to determine their mutation status in part because they are unaware of their cancer risk and the availability of BRCA testing. Participation in a family information service (FIS), of which we have provided more than 100 sessions during the past 30 years, has been seen to effectively allow family members to be educated regarding their cancer genetic risk and potential benefits from cancer control measures such as mutation testing. However, the effect of the FIS on the rate of mutation testing has not been studied. One thousand five hundred seventy-four eligible (>18-year old, at a 25% or higher pedigree risk) members from 60 extended HBOC families with BRCA1/2 mutations were invited to attend a FIS to learn about their risk and undergo genetic testing. The rates of mutation testing were compared between those who had attended an FIS, and those who had not with chi-squared test and logistic regression analysis. Seventy five percent (334/444) of FIS attendees had undergone mutation testing following or during an FIS which was significantly higher than the 33.8% (382/1130) rate among nonattendees (p < 0.0001). Logistic regression analysis showed that FIS attendance, breast-ovarian cancer history, gender, and age were significant variables for undertaking a mutation test. FIS attendance significantly increased the rate of mutation testing among high-risk family members.

Trend and racial disparities in infant mortality rate in Texas from 1990 to 2004.

PURPOSE: To determine the trend and disparities in infant mortality rate (IMR) from 1990 to 2004 in Texas, which is one of the few states with severe physician shortage in the United States. METHODS: Trend analysis and Poisson regression were performed with data from Texas Department of State for Health Services and other Web sites. RESULTS: IMR decreased from 1990 to 2000 followed by a trend of increase from 2000 to 2004 in Texas. The recent trend of increase in IMR was observed in all ethnic groups. IMR was associated with ethnicity, area of residence in Texas (rural vs urban areas in east vs south vs west), median income index, and primary care physician supply (primary care physician to population ratio). IMR in blacks was more than 2 times that of other ethnic groups, and the gap had been increasing since 1997. The recent increasing trend in IMR coincided with a decreasing trend in primary care physician supply and a decrease or a slower increase in median income index. CONCLUSIONS: IMR increased in recent years, particularly in African Americans in Texas. Measures should be taken to reverse the worsening trend in IMR and to reduce regional and racial disparities.

Higher US Rural Mortality Rates Linked To Socioeconomic Status, Physician Shortages, And Lack Of Health Insurance.

All-cause mortality rates in rural areas have exceeded those in urban areas of the US since the 1980s, and the gap continues to widen. Yet no definitive causes of this difference are known, and within-state differences that might be amenable to state-level policy have not been explored. An analysis of 2016 state-level data indicated that rural mortality exceeded urban mortality in all but three states, with substantial variability in both rates across states. Overall, higher rural mortality at the state level can be mainly explained by three factors: socioeconomic deprivation, physician shortages, and lack of health insurance. To a certain degree, these factors reflect a state's health policies, such as expansion of eligibility for Medicaid, health infrastructure, and socioeconomic conditions. Our findings suggest that state and federal policy efforts to address rural-urban disparities in these areas could alleviate the higher rates of all-cause mortality faced by rural US residents.

Factors associated with undiagnosed open-angle glaucoma: the Thessaloniki Eye Study.

PURPOSE: To identify factors associated with undiagnosed open-angle glaucoma (OAG), primary open-angle glaucoma (POAG), and pseudoexfoliative glaucoma (PEXG) in an elderly population in Thessaloniki, Greece. DESIGN: Cross-sectional population-based study. METHODS: Randomly selected subjects > or =60 years (n = 2,554) participated in the study. Subjects were classified as having POAG or PEXG according to specific criteria and using a two-scale definition of glaucoma. Undiagnosed glaucoma was defined as absence of either prior diagnosis of glaucoma or ocular hypertension or prior medical treatment for glaucoma or prior glaucoma surgery. Logistic regression analyses were performed with age, gender, family history of glaucoma, history of cataract surgery, visual acuity, vertical cup-to-disk (C/D) ratio, intraocular pressure, Advanced Glaucoma Intervention Study visual field score, time since last eye doctor visit, and type of OAG as covariates. RESULTS: The prevalence of undiagnosed glaucoma was 57.1% (56/98) for POAG, significantly higher than the prevalence of 34.9% (15/43) for PEXG (P = .017). POAG patients presented three to four times increased risk to be undiagnosed compared with PEXG patients (P = .02 and P = .04, respectively). Patients with OAG who had not visited an ophthalmologist during the last year had six times an increased risk to be undiagnosed (P = .003). In POAG, smaller vertical C/D ratio was statistically significantly associated with an increased risk to be undiagnosed (P = .008). CONCLUSIONS: Lack of regular visits to an ophthalmologist was a major factor for undiagnosed OAG. POAG was more likely to be undiagnosed than PEXG. Since C/D ratio was associated with undiagnosed POAG, standardized protocols involving thorough evaluation of the optic disk are recommended for ophthalmologists.

Ethical, legal and social issues of genetic studies with African immigrants as research subjects.

There is growing interest in exploring gene-environment interactions in the etiology of diseases in immigrants from sub-Saharan Africa. Our experience working with the Sudanese immigrant population in Omaha, NE, makes clear the pressing need for geneticists and federal and local funding agencies to address the ethical, legal and social implications of genetic research with such vulnerable populations. Our work raises several questions. How does one design research with African immigrant participants to assure it is ethical? Many immigrants may not understand the purposes, risks and benefits involved in research because of low literacy rates, one of the results of civil wars, or concepts of biologic science foreign to their cultures. Is it possible to obtain truly informed consent? Do African immigrants perceive genetic research using them as subjects as racist? Is genetic research on minorities "biopiracy" or "bio-colonialism?" In our experience, some Sudanese immigrants have challenged the legality and ethics of genetic studies with profit-making as an end. We have concluded that it is essential to educate African immigrant or any other non-English-speaking immigrant participants in research using lay language and graphic illustrations before obtaining consent. Cultural proficiency is important in gaining the trust of African immigrants; profit-sharing may encourage their participation in genetic research to benefit all; involvement of African immigrant community leaders in planning, delivery and evaluation using the community-based participatory research approach will facilitate healthcare promotion, health literacy education, as well as genetic research. It is crucial to address the ethical, legal and social implications of genetic studies with African immigrants as research subjects.

Inherited, familial and sporadic primary open-angle glaucoma.

UNLABELLED: The U.S. surgeon general has recently launched a campaign to promote the awareness of the medical value of family history. Further attention should be paid to familial aggregation. Accordingly, we suggest that primary open-angle glaucoma (POAG) be classified into inherited, familial and sporadic categories. The three classes of POAG differ not only in inheritance pattern and familial aggregation but also in methodology and outcome of gene mapping. Inherited POAG follows Mendelian inheritance and has been linked to seven chromosomal loci to date by linkage analysis. Familial POAG does not show a clear pattern of Mendelian inheritance and is typically studied by sib-pair analysis and family-based association analysis, although the results often require replication in multiple samples. Interestingly, many sporadic POAG cases carry known POAG-causing mutations, suggesting genetic predisposition as well. Based on published data, we estimated that inherited and familial POAG cases may account for approximately 72% of all POAG cases. We further formulated a mathematic model to estimate disease prevalence and mutation frequency taking both ethnic background and familial aggregation into consideration. CONCLUSION: POAG appears to be mainly caused by genetic predisposition in interaction with other risk factors such as age. The suggested classification of POAG may serve as a useful guide in clinical practice and genetic studies where ethnic background and familial aggregation must be taken into consideration.

The Health Insurance Gap After Implementation of the Affordable Care Act in Texas.

Households with incomes between 18% and 99% of the federal poverty level (FPL) are ineligible for Medicaid or enrollment in the health insurance exchange marketplace in Texas, resulting in the health insurance gap. We sought to determine the number of non-elderly adult Texans (NEATs) aged between 18 and 64 years in the insurance gap in rural vs urban areas in East Texas, West Texas, and South Texas. Data were obtained from the US Census Bureau website. In 2014, there were 1,101,000 NEATs in the insurance gap, accounting for 24.5% of all uninsured persons in Texas. The gap was significantly higher in rural vs urban areas in East and South Texas and in Texas as a whole. Large coverage gaps in states like Texas not expanding Medicaid under the Affordable Care Act pose major hurdles to reducing the number of uninsured individuals in these states.

Phenotypic and genotypic heterogeneity in the Lynch syndrome: diagnostic, surveillance and management implications.

Lynch syndrome is the most common form of hereditary colorectal cancer (CRC). This review covers the cardinal features of Lynch syndrome with particular emphasis upon its diagnostic criteria, molecular genetics, natural history, genetic counseling, surveillance and management. Considerable attention has been given to the etiologic role of mismatch repair (MMR) genes as well as low penetrance alleles and modifier genes. The American founder mutation, a deletion of exons 1-6 of MSH2, is discussed in some detail, owing to its high frequency in the US (19 000-30 000 carriers). Genetic counseling is essential prior to patients' undergoing DNA testing and again when receiving their test results. Families with a lower incidence of CRC and extracolonic cancers, in the face of being positive for Amsterdam I criteria but who do not have MMR deficiency by tumor testing, are probably not Lynch syndrome, and thereby should preferably be designated as familial CRC of undetermined type. Patients who are either noncompliant or poorly compliant with colonoscopy, and who are MMR mutation positive, may be candidates for prophylactic colectomy, while MMR mutation-positive women who are noncompliant with gynecologic surveillance may be candidates for prophylactic hysterectomy and bilateral salpingo-oophorectomy.

Patient responses to the disclosure of BRCA mutation tests in hereditary breast-ovarian cancer families.

Limited attention has been given to the impact of BRCA mutation disclosure on participants' psychological reaction and cancer control compliance. We asked women (290 mutation-positive, 370 mutation-negative) from 84 hereditary breast-ovarian cancer (HBOC) families with known deleterious BRCA mutations to participate in an evaluation regarding cancer prevention recommendations before and after BRCA mutation disclosure. Both men and women (n = 780) were invited to complete a questionnaire to evaluate their psychological response to BRCA mutation disclosure. Before BRCA testing, 23.0% (152 of 660) of these women underwent prophylactic bilateral mastectomy, oophorectomy, or both; of these, 53% (80 of 152) were subsequently found to be mutation negative. After mutation disclosure, 52.9% (110 of 208) of mutation carriers and 0% (0 of 203) of noncarriers underwent prophylactic surgeries. These changes were statistically significant compared with before disclosure (P < 0.0001). The rate of transvaginal ovarian ultrasound screening was significantly increased in mutation carriers (P < 0.015) and marginally decreased in noncarriers (P = 0.063) post disclosure. Psychologically, compared with noncarriers without cancer, a significantly higher percentage of carriers, regardless of their cancer status, felt guilt about passing a mutation to their children, worried about developing additional cancer or their children developing cancer, and were concerned about health insurance discrimination. Despite these psychological consequences, carriers and noncarriers reported a positive attitude toward genetic testing.

The I1307K APC polymorphism in Ashkenazi Jews with colorectal cancer: clinical and pathologic features.

Colorectal cancer is common in Ashkenazi Jews. The I1307K APC mutation occurs in 6-7% of Ashkenazi Jews and increases the risk of colorectal cancer. This study aimed to describe the clinical, pathologic and epidemiologic features of colorectal cancer in I1307K carriers to determine whether there were any features which might warrant individual screening for the mutation. In all, 215 Ashkenazi Jews with a personal history of colorectal cancer were enrolled. Clinical and family history, pathology reports, and slides were obtained and blood drawn for I1307K determination. The presence of the mutation was determined by PCR from white blood cell DNA. Colorectal cancer pathology slides were read in a blinded fashion. Of the 215 enrolled patients, 26 (12.1%) tested positive for I1307K. There was no difference in the pathologic features between colorectal cancers in Ashkenazi carriers compared to noncarriers. There was no difference in the age at diagnosis or history of second or other primaries. Carriers had an increased likelihood of having a first-degree relative with colorectal cancer (50%) compared to noncarriers (28%, P < 0.04). We could find no distinguishing feature other than family history that characterizes I1307K positive colorectal cancers. We could find no group of Ashkenazi Jews with colorectal cancer for whom screening for I1307K would be clinically useful.

Race, ethnicity and prevalence of primary open-angle glaucoma.

BACKGROUND: Recently, some authors pooled data from studies on the Dutch, Australians and Americans of European origin in an attempt to predict the prevalence of primary open-angle glaucoma (POAG) in the United States. PURPOSE: To examine potential ethnic diversity in the prevalence of POAG among populations of the "same race." METHODS: Medical literature was searched, and 11 population-based studies on populations of African origin and five on populations of European origin were identified. RESULTS: The prevalence of POAG was significantly higher in white Australians than in the Dutch (p<0.001) and was significantly lower (p<0.001) among black populations in South Africa, Nigeria, Tanzania and the United States than in Ghana, St. Lucia or Barbados. Notably, the prevalence was significantly lower in Afro Caribbeans living in London than in St. Lucia or Barbados (p<0.001). There was, however, inconsistency in the definition of POAG among the different studies. CONCLUSIONS: There is a wide range in the prevalence of POAG among populations of the same "race," which might be attributed to the different methodology and definition of POAG; potential difference in social, behavioral and environmental factors; and/or genetic predisposition. Scrutiny is warranted when pooling data from different ethnic groups of the "same race" in meta-analyses.