South Asian Cohort Research Articles

Ethnic South Asian ischaemic stroke patients have a higher prevalence of a family history of vascular disease compared to age, gender and diabetes-matched ethnic Chinese subjects

Family history is a known non-modifiable risk factor of stroke. We aimed to compare the frequency of a family history of vascular disease between ethnic South Asian and Chinese stroke patients. We studied consecutive ethnic South Asian and Chinese ischaemic stroke patients matched for age, gender and presence of diabetes. Among the 152 matched pairs, ethnic South Asian ischaemic stroke patients had a higher frequency of vascular family history (IHD OR 3.465 p < 0.001; CVD OR 1.754 p = 0.059; and either IHD or CVD OR 2.169 p = 0.003) compared to matched ethnic Chinese patients, independent of past IHD history and stroke subtype. In the ethnic South Asian cohort, patients ≤ 60 years old had a higher frequency of a family history of IHD (37% vs 13%, p < 0.001), CVD (34% vs 15%, p = 0.005) and either IHD or CVD (52% vs 25%, p < 0.001) compared to those > 60 years. Family history of vascular disease is common among ethnic South Asian ischaemic stroke patients, particularly among those ≤ 60 years old. We postulate that the higher frequency of a vascular family history among ethnic South Asians compared to ethnic Chinese may be explained by genetic, environmental and lifestyle influences, or interactions between these factors.

Age-dependent reference intervals for measured bioavailable testosterone on the Siemens Advia Centaur: Ethnicity-specific values not necessary for South Asians

Objectives To determine reference intervals for bioavailable testosterone for the Siemens Centaur analyzer and to assess the need for ethnicity-specific ranges for total testosterone and/or bioavailable testosterone in South Asians. Design and methods Testosterone was measured before and after ammonium sulphate precipitation on specimens collected from a small cohort of healthy male South Asians and Europeans. Results Inter-ethnicity differences in BioT and TT were not significant. Age-specific BioT reference intervals are reported. Conclusions Ethnicity-specific TT and BioT reference intervals for South Asians do not appear necessary.

Prevalence and clinical characteristics of maternally inherited diabetes and deafness caused by the mt3243A &gt; G mutation in young adult diabetic subjects in Sri Lanka

The maternally inherited mt3243A > G mutation is associated with a variable clinical phenotype including diabetes and deafness (MIDD). We aimed to determine the prevalence and clinical characteristics of MIDD in a large South Asian cohort of young adult-onset diabetic patients from Sri Lanka. DNA was available from 994 subjects (age of diagnosis 16-40 years, age at recruitment < or = 45 years). Mutation screening was performed using a QRT-PCR method on an ABI 7900HT system using sequence-specific probes. Samples with heteroplasm > or = 5.0% were considered positive. Nine (four males) mutation-positive subjects were identified (prevalence 0.9%). They were diagnosed at a younger age (25.9 +/- 4.8 years vs. 31.9 +/- 5.6 years, P = 0.002) and were lean (body mass index [BMI] 18.7 +/- 2.7 kg/m(2) vs. 24.7 +/- 4.0 kg/m(2), P < 0.001) compared to NMCs. One mutation-positive subject (11.1%) had metabolic syndrome, compared to 633 (64.3%) of NMCs. Insulin therapy within 6 months of diagnosis was used in four (44.0%) carriers compared to 6.9% of NMCs (P = 0.002). Combined screening criteria of any two of maternal history of diabetes, personal history of hearing impairment and family history of hearing impairment only identified five (55%) of the carriers, with a positive predictive value of 7.4%. The prevalence of mt3243A > G mutation among young adult-onset diabetic subjects from Sri Lanka was 0.9%. Our study demonstrates that a maternal family history of diabetes and either a personal and/or family history of deafness only distinguish half of patients with MIDD from Sri Lankan subjects with young-onset diabetes.

Common variants of the TCF7L2gene are associated with increased risk of type 2 diabetes mellitus in a UK-resident South Asian population

BackgroundRecent studies have implicated variants of the transcription factor 7-like 2 (TCF7L2) gene in genetic susceptibility to type 2 diabetes mellitus in several different populations. The aim of this study was to determine whether variants of this gene are also risk factors for type 2 diabetes development in a UK-resident South Asian cohort of Punjabi ancestry.MethodsWe genotyped four single nucleotide polymorphisms (SNPs) of TCF7L2 (rs7901695, rs7903146, rs11196205 and rs12255372) in 831 subjects with diabetes and 437 control subjects.ResultsThe minor allele of each variant was significantly associated with type 2 diabetes; the greatest risk of developing the disease was conferred by rs7903146, with an allelic odds ratio (OR) of 1.31 (95% CI: 1.11 – 1.56, p = 1.96 × 10-3). For each variant, disease risk associated with homozygosity for the minor allele was greater than that for heterozygotes, with the exception of rs12255372. To determine the effect on the observed associations of including young control subjects in our data set, we reanalysed the data using subsets of the control group defined by different minimum age thresholds. Increasing the minimum age of our control subjects resulted in a corresponding increase in OR for all variants of the gene (p ≤ 1.04 × 10-7).ConclusionOur results support recent findings that TCF7L2 is an important genetic risk factor for the development of type 2 diabetes in multiple ethnic groups.

Visceral adipose tissue accumulation differs according to ethnic background: results of the Multicultural Community Health Assessment Trial (M-CHAT)

Background: It was suggested that body fat distribution differs across ethnic groups, and this may be important when considering risk of disease. Previous studies have not adequately investigated differences in discrete regions of abdominal adiposity across ethnic groups.Objective: We compared the relation between abdominal adipose tissue and total body fat between persons living in Canada of Aboriginal, Chinese, and South Asian origin with persons of European origin.Design: Healthy Aboriginal, Chinese, European, and South Asian participants (n = 822) aged between 30 and 65 y were matched by sex, ethnicity, and body mass index (BMI; in kg/m2) range. Total abdominal adipose tissue (TAT), subcutaneous abdominal adipose tissue (SAT), visceral adipose tissue (VAT), total body fat mass, lifestyle, and demographics were assessed. Relations between BMI and total body fat, TAT, SAT, and VAT and between total body fat and TAT, SAT, and VAT were investigated.Results: BMI significantly underestimated VAT in all non-European groups. Throughout a range of total body fat mass, VAT was not significantly different between the Aboriginals and the Europeans. With total body fat >9.1 kg, Chinese participants had increasingly greater amounts of VAT than did the Europeans (P for interaction = 0.008). South Asians had less VAT with total body fat >37.4 kg but more VAT below that amount than did Europeans (P for interaction < 0.001).Conclusion: Compared with Europeans, the Chinese and South Asian cohorts had a relatively greater amount of abdominal adipose tissue, and this difference was more pronounced with VAT. No significant differences were observed between the Aboriginals and the Europeans.

Derivation and validation of diabetes risk score for urban Asian Indians

Objective: Simple risk scores for identifying people with undiagnosed diabetes have been developed, mostly in Caucasian groups. This may not be suitable for Asian Indians, therefore this study was undertaken to develop and validate a simple diabetes risk score in an urban Asian Indian population with a high prevalence of diabetes. We also tested whether this score was applicable to South Asian migrants living in a different cultural context. Research design and methods: A population based Cohort of 10,003 participants aged ≥20 years was divided into two equal halves (Cohorts 1 and 2), after excluding people with known diabetes. Cohort 1 ( n = 4993) was used to derive the risk score. Validation of the score was performed in the other half of the survey population (Cohort 2) ( n = 5010). The validation was also done in a separate survey population in Chennai, India (Cohort 3) ( n = 2002) (diagnosis of diabetes was based on OGTT) and in the South Asian Cohort of the 1999 Health Survey for England ( n = 676) (fasting glucose value ≥ 7 mmol/l and HbA1c ≥ 6.5% were used for diagnosis). A logistic regression model was used to compute the β coefficients for risk factors. The risk score value was derived from a receiver operating characteristic curve. Results: The significant risk factors included in the risk score were age, BMI, waist circumference, family history of diabetes and sedentary physical activity. A risk score value of >21 gave a sensitivity, specificity, positive predictive value and negative predictive value of 76.6%, 59.9%, 9.4% and 97.9% in Cohort 1, 72.4%, 59%, 8.3% and 97.6% in Cohort 2 and 73.7%, 61.0%, 12.2% and 96.9% in Cohort 3, respectively. The higher distribution of risk factors in the UK Cohort means that at the same cut point the score was much more sensitive but also less specific. (sensitivity 92.2%, specificity 25.7%, positive predictive value of 21.6% and negative predictive value of 93.7%). Conclusions: A diabetes risk score involving simple non-biochemical measurements was developed and validated in a native Asian Indian population. This easily applicable simple score could play an important role as the first step in the process of identifying individuals with an increased likelihood of having prevalent but undiagnosed diabetes. The different distribution of risk factors with the migrant Asian Indians living in England and the different relationship between sensitivity and specificity for the same score demonstrate that risk scores and cut-points developed and tested even within one ethnic group cannot be generalized to individuals of the same ethnic group living in a different cultural setting where the distribution of risk factors for diabetes is different.

Cortisol and the metabolic syndrome in South Asians.

The cardiovascular risk factors which comprise the metabolic syndrome are associated with increased hypothalamic-pituitary-adrenal axis (HPAA) activity in some Caucasian populations. South Asians have high rates of cardiovascular disease and its risk factors. We have investigated the relationships between HPAA activity, adiposity and the metabolic syndrome in a South Asian population. Cross-sectional cohort study. A total of 509 men and women born at the Holdsworth Memorial Hospital, Mysore, South India between 1934 and 1954 and still living in the area. Fasting 09.00 h cortisol and corticosteroid-binding globulin. The cohort had previously been investigated for features of the metabolic syndrome. At 09.00 h, cortisol concentration was strongly associated with systolic and diastolic blood pressure (r = 0.25 and r = 0.24, respectively; P < 0.001), fasting glucose concentration (r = 0.26; P < 0.001), insulin resistance (r = 0.20; P < 0.001) and fasting triglyceride concentration (r = 0.17; P < 0.001). In general, higher cortisol concentrations added to the effect of adiposity in increasing cardiovascular risk factors, but there was evidence of an interaction between cortisol and adiposity in determining fasting glucose concentration (P = 0.045) and insulin resistance (P = 0.006). Associations between 09.00 h cortisol concentration and cardiovascular risk factors in this South Asian cohort were stronger than those previously shown in Caucasian populations, despite similar mean cortisol concentrations, and were amplified by adiposity. This suggests that increased glucocorticoid action may contribute to ethnic differences in the prevalence of the metabolic syndrome, particularly among men and women with a higher body mass index.