Community perceptions of reasons for preference for consanguineous marriages in Pakistan

Multiple genetic variants explain measurable variance in type 2 diabetes-related traits in Pakistanis

AIMS/HYPOTHESIS

Multiple genetic variants are associated with type 2 diabetes-related traits in Europeans, but their role in South Asian populations needs further study. We hypothesised that genetic variants associated with diabetes-related traits in Europeans would explain a similar proportion of phenotypic variance in a Pakistani population and could be used in Mendelian randomisation analyses.

METHODS

We used data from 2,131 individuals from the Control of Blood Pressure and Risk Attenuation Trial (COBRA) in Karachi, Pakistan. Individuals were aged 40 years or older.

RESULTS

Combining information from multiple genetic variants showed that fasting glucose, BMI, triacylglycerol, and systolic and diastolic blood pressure variants explained 2.9%, 0.7%, 5.5%, 1.2% and 1.8% of the variance in those traits respectively. Genetic risk scores of fasting glucose, triacylglycerol, BMI, systolic blood pressure and diastolic blood pressure variants were associated with these traits, with per allele SD effects of 0.057 (95% CI 0.041, 0.074), p=3.44 × 10(-12), 0.130 (95% CI 0.105, 0.155), p=2.9 × 10(-21), 0.04 (95% CI 0.014, 0.072), p=0.004, 0.031 (95% CI 0.016, 0.047), p=7.9 × 10(-5), 0.028 (95% CI 0.015, 0.042), p = 5.5 × 10(-5), respectively. These effects are consistent with those observed in Europeans, except that the effect of triacylglycerol variants in South Asians was slightly lower. Mendelian randomisation provided evidence that genetically influenced, raised triacylglycerol levels do not causally affect type 2 diabetes risk to the extent predicted from observational data (p=0.0003 for difference between observed and instrumental variables correlations).

CONCLUSIONS/INTERPRETATION

Genetic variants identified in Europeans are associated with type 2 diabetes-related traits in Pakistanis, with comparable effect sizes. Larger studies are needed to perform adequately powered Mendelian randomisation and help dissect the relationships between type 2 diabetes-related traits in diverse South Asian subgroups.

Turkish population structure and genetic ancestry reveal relatedness among Eurasian populations

Turkey has experienced major population movements. Population structure and genetic relatedness of samples from three regions of Turkey, using over 500,000 SNP genotypes, were compared together with Human Genome Diversity Panel (HGDP) data. To obtain a more representative sampling from Central Asia, Kyrgyz samples (Bishkek, Kyrgyzstan) were genotyped and analysed. Principal component (PC) analysis reveals a significant overlap between Turks and Middle Easterners and a relationship with Europeans and South and Central Asians; however, the Turkish genetic structure is unique. FRAPPE, STRUCTURE, and phylogenetic analyses support the PC analysis depending upon the number of parental ancestry components chosen. For example, supervised STRUCTURE (K=3) illustrates a genetic ancestry for the Turks of 45% Middle Eastern (95% CI, 42-49), 40% European (95% CI, 36-44) and 15% Central Asian (95% CI, 13-16), whereas at K=4 the genetic ancestry of the Turks was 38% European (95% CI, 35-42), 35% Middle Eastern (95% CI, 33-38), 18% South Asian (95% CI, 16-19) and 9% Central Asian (95% CI, 7-11). PC analysis and FRAPPE/STRUCTURE results from three regions in Turkey (Aydin, Istanbul and Kayseri) were superimposed, without clear subpopulation structure, suggesting sample homogeneity. Thus, this study demonstrates admixture of Turkish people reflecting the population migration patterns.

Socioeconomic, demographic and legal influences on consanguinity and kinship in northern coastal Sweden 1780-1899

Most studies on consanguinity have been conducted on contemporary populations and have focused on the prevalence and types of preferred intra-familial marriage. With its comprehensive birth, marriage and deaths records dating back to the late 17th century, and the legal bar on first cousin marriage removed in the mid-19th century, Sweden offers unique opportunities to examine the factors that determine by whom, where and why consanguineous marriages were contracted. The present study covers the period 1780-1899 and presents a detailed portrait of cousin and sibling exchange marriages in the Skellefteå region of northern coastal Sweden. The combined prevalence of first, second and third cousin marriage increased from 2.3% in 1790-1810 to 8.8% in 1880-1899, and multi-generation consanguinity also increased significantly over the study period. The distribution and prevalence of first cousin marriages was strikingly non-random, with a significantly greater propensity for consanguinity among land-owning families, especially involving first-born sons, within specific pedigrees, and in a number of more remote inland communities. Additional factors associated with a greater likelihood of consanguineous marriage included physical or mental disability among males, and among females the prior birth of an illegitimate child. Besides the inherent interest in the social and demographic structure of this region of northern Sweden during the course of the 19th century, in future studies it will be important to determine the degree to which the observed patterns of consanguineous and sibling exchange marriages in these past generations could have influenced present-day genetic structure.

On some novel aspects of consanguineous marriages

Consanguineous marriages, often viewed as incestuous and objectionable, are more widespread than commonly perceived. They integrate multiple facets of human adaptation: economic, cultural and genetic. The widely touted explanation for the origin and persistence of consanguinity is that it provides many socioeconomic benefits; however, this view may be too simplistic. The bias against consanguinity may preclude an objective understanding of this sociobiological puzzle. Inbreeding increases the speed of selection of beneficial recessive and co-dominant alleles, e.g. those that protect against diseases. In populations endemic with malaria, the prevalence of consanguineous marriages and the frequency of alleles protective against malaria are both very high. Thus, consanguinity could theoretically increase the relative fitness of a population under specific ecological conditions; sometimes, the overall genetic benefits may exceed genetic costs of inbreeding. We discuss some recent evidence from studies on inbreeding along with the reasons responsible for the mating strategy found in some human populations. We contend that a better appreciation of our inherent biases and potential genetic benefits of inbreeding in specific ecological conditions would help us to appreciate the wider picture of consanguinity.

Genomic runs of homozygosity record population history and consanguinity

The human genome is characterised by many runs of homozygous genotypes, where identical haplotypes were inherited from each parent. The length of each run is determined partly by the number of generations since the common ancestor: offspring of cousin marriages have long runs of homozygosity (ROH), while the numerous shorter tracts relate to shared ancestry tens and hundreds of generations ago. Human populations have experienced a wide range of demographic histories and hold diverse cultural attitudes to consanguinity. In a global population dataset, genome-wide analysis of long and shorter ROH allows categorisation of the mainly indigenous populations sampled here into four major groups in which the majority of the population are inferred to have: (a) recent parental relatedness (south and west Asians); (b) shared parental ancestry arising hundreds to thousands of years ago through long term isolation and restricted effective population size (N_e), but little recent inbreeding (Oceanians); (c) both ancient and recent parental relatedness (Native Americans); and (d) only the background level of shared ancestry relating to continental N_e (predominantly urban Europeans and East Asians; lowest of all in sub-Saharan African agriculturalists), and the occasional cryptically inbred individual. Moreover, individuals can be positioned along axes representing this demographic historic space. Long runs of homozygosity are therefore a globally widespread and under-appreciated characteristic of our genomes, which record past consanguinity and population isolation and provide a distinctive record of the demographic history of an individual's ancestors. Individual ROH measures will also allow quantification of the disease risk arising from polygenic recessive effects.

Consanguineous Marriage and Human Evolution

Mate choice among early human groups and in many historical populations was subject to both demographic and social constraints, ensuring that most unions were between couples who had coinherited substantial proportions of their genomes from common ancestors. Even in populations in which close consanguineous marriage was proscribed, community endogamy would have been sufficient to ensure high levels of homozygosity. Consanguineous marriage remains the choice of an estimated 10.4% of the global population, although there has been an overall decline in its popularity, especially in developed countries. Recent studies have indicated that the shift from consanguineous marriage to panmixia has been accompanied by a reduction in homozygosity. The concomitant predicted decrease in incidence of both recessive single-gene disorders and more common adult-onset diseases will have a significant impact on the health of future generations.

Bleeding disorders in the tribe: result of consanguineous in breeding

OBJECTIVE

To determine the frequency and clinical features of bleeding disorders in the tribe as a result of consanguineous marriages.

DESIGN

Cross Sectional Study

INTRODUCTION

Countries in which consanguinity is a normal practice, these rare autosomal recessive disorders run in close families and tribes. Here we describe a family, living in village Ali Murad Chandio, District Badin, labeled as haemophilia.

PATIENTS & METHODS

Our team visited the village & developed the pedigree of the whole extended family, up to seven generations. Performa was filled by incorporating patients, family history of bleeding, signs & symptoms, and bleeding from any site. From them 144 individuals were screened with CBC, bleeding time, platelet aggregation studies & RiCoF. While for PT, APTT, VWF assay and Factor VIII assay, samples were kept frozen at -70 degrees C until tested.

RESULTS

The family tree of the seven generations comprises of 533 individuals, 63 subjects died over a period of 20 years and 470 were alive. Out of all those 144 subjects were selected on the basis of the bleeding history. Among them 98(68.1%) were diagnosed to have a bleeding disorder; 44.9% patients were male and 55.1% patients were female. Median age of all the patients was 20.81, range (4 months- 80 yrs). The results of bleeding have shown that majority had gum bleeding, epistaxis and menorrhagia. Most common bleeding disorder was Von Willebrand disease and Platelet functional disorders.

CONCLUSION

Consanguineous marriages keep all the beneficial and adversely affecting recessive genes within the family; in homozygous states. These genes express themselves and result in life threatening diseases. Awareness, education & genetic counseling will be needed to prevent the spread of such common occurrence of these bleeding disorders in the community.

Consanguinity and increased risk for schizophrenia in Egypt

BACKGROUND

Consanguinity has been suggested as a risk factor for psychoses in some Middle Eastern countries, but adequate control data are unavailable. Our recent studies in Egypt have shown elevated parental consanguinity rates among patients with bipolar I disorder (BP1), compared with controls. We have now extended our analyses to schizophrenia (SZ) in the same population.

METHODS

A case-control study was conducted at Mansoura University Hospital, Mansoura, Egypt (SZ, n=75; controls, n=126, and their available parents). The prevalence of consanguinity was estimated from family history data ('self report'), followed by DNA analysis using short tandem repeat polymorphisms (STRPs, n=63) ('DNA-based' rates).

RESULTS

Self-reported consanguinity was significantly elevated among the patients (SZ: 46.6%, controls: 19.8%, OR 3.53, 95% CI 1.88, 6.64; p=0.000058, 1 d.f.). These differences were confirmed using DNA-based estimates for coefficients of inbreeding (inbreeding coefficients as means+/-standard error, cases: 0.058+/-0.007, controls: 0.022+/-0.003).

CONCLUSIONS

Consanguinity rates are significantly elevated among Egyptian SZ patients in the Nile delta region. The associations are similar to those observed with BP1 in our earlier study. If replicated, the substantial risk associated with consanguinity raises public health concerns. They may also pave the way for gene mapping studies.

Choice of kin in consanguineous marriages: effects of altruism and ecological factors

BACKGROUND

Despite being associated with multiple genetic problems, consanguineous marriages continue to remain extremely prevalent worldwide. Studying the variation of kin preferences in diverse inbred societies may provide some answers to this paradox.

AIM

To find the reasons for specific kin choice in different geographical areas of the world.

METHOD

We used a set of sociobiological rules (kin altruism, sexuality and inbreeding avoidance) and ecological constraints (e.g. tribal warfare, food availability) that influence human behaviour. The cumulative help that the extended family can provide to a nuclear family was calculated using the coefficient of relatedness between kin in different types of consanguineous families.

RESULTS

The maximum potential support for kin markedly varied between different types of consanguineous marriages. Overall, members of consanguineous families received up to two-and-half times more support than members of non-consanguineous families. In various inbred cultures, preference for a specific type of kin was determined by prevailing ecological limitations and sociobiological factors interacting in a complex manner.

CONCLUSION

In different inbred populations, the ideal kin for a consanguineous marriage is the one who can provide the most altruistic support; however, this choice is influenced by biological rules of behaviour and ecological constraints.

Security lies in obedience--voices of young women of a slum in Pakistan

BACKGROUND

Existing literature shows that young people, especially women, have poor knowledge about sexuality and reproductive health. Many of the difficulties young women experience are related to beliefs and expectations in society making them more vulnerable to reproductive ill health. The objective of this study was to explore how young women living in a slum in Islamabad are prepared for marriage and how they understand and perceive their transition to marriage and the start of sexual and childbearing activity.

METHODS

Twenty qualitative interviews and three focus group discussions were conducted with young women residing in a slum of Islamabad. Content analysis was used to explore how the participants represented and explained their situation and how decisions about their marriage were made.

RESULTS

The main theme identified was security lies in obedience. The two sub-themes contributing to the main theme were socialization into submissiveness and transition into adulthood in silence. The theme and the sub-themes illustrate the situation of young women in a poor setting in Pakistan.

CONCLUSION

The study demonstrates how, in a culture of silence around sexuality, young women's socialization into submissiveness lays the foundation for the lack of control over the future reproductive health that they experience.

Evolution in health and medicine Sackler colloquium: Consanguinity, human evolution, and complex diseases

There is little information on inbreeding during the critical early years of human existence. However, given the small founding group sizes and restricted mate choices it seems inevitable that intrafamilial reproduction occurred and the resultant levels of inbreeding would have been substantial. Currently, couples related as second cousins or closer (F >or= 0.0156) and their progeny account for an estimated 10.4% of the global population. The highest rates of consanguineous marriage occur in north and sub-Saharan Africa, the Middle East, and west, central, and south Asia. In these regions even couples who regard themselves as unrelated may exhibit high levels of homozygosity, because marriage within clan, tribe, caste, or biraderi boundaries has been a long-established tradition. Mortality in first-cousin progeny is approximately 3.5% higher than in nonconsanguineous offspring, although demographic, social, and economic factors can significantly influence the outcome. Improving socioeconomic conditions and better access to health care will impact the effects of consanguinity, with a shift from infant and childhood mortality to extended morbidity. At the same time, a range of primarily social factors, including urbanization, improved female education, and smaller family sizes indicate that the global prevalence of consanguineous unions will decline. This shift in marriage patterns will initially result in decreased homozygosity, accompanied by a reduction in the expression of recessive single-gene disorders. Although the roles of common and rare gene variants in the etiology of complex disease remain contentious, it would be expected that declining consanguinity would also be reflected in reduced prevalence of complex diseases, especially in population isolates.

The effect of religious, cultural and social identity on population genetic structure among Muslims in Pakistan

Knowledge of historical demography and contemporary social stratification can be valuable in understanding disease patterns, including genetic disorders, especially in communities that have a high prevalence of endogamous and/or consanguineous marriages. This paper provides a background to the religious, historical and socio-cultural factors that have helped define the bounds of endogamy for Muslims in undivided India and more specifically since the creation of Pakistan. The preference for endogamous marriage is based on the clan-oriented nature of the society, which values and actively seeks similarities in social group identity based on several factors, including religious, sectarian, ethnic, and tribal/clan affiliation. Religious affiliation is itself multi-layered and includes religious considerations other than being Muslim, such as sectarian identity (e.g. Shia or Sunni, etc.) and religious orientation within the sect (Isnashari, Ismaili, Ahmedi, etc.). Both ethnic affiliation (e.g. Sindhi, Baloch, Punjabi, etc.) and membership of specific biraderis or zat/quoms are additional integral components of social identity. Within the bounds of endogamy defined by the above parameters, close consanguineous unions are preferential due to a congruence of key features of group- and individual-level background factors.

Risk factors for breast cancer in Pakistani women aged less than 45 years

BACKGROUND

There has been an increase in the incidence of breast cancer in previously low-risk Asian countries. It is important to identify the risk factors for Asian women, as little information currently exists for this population.

AIM

The objective of the study was to determine risk factors for breast cancer among Pakistani women.

SUBJECTS AND METHODS

498 cases younger than 45 years were interviewed from 1 July 1997 to 31 December 1998 at two major cancer hospitals. Age-matched population-based controls were selected from two cities and two villages to represent urban and rural areas. For the variables under study, cases and controls were compared by t-test. Conditional multiple logistic regression models were applied to the data set.

RESULTS

Women with BMI >or= 30, with a family history of breast cancer and who were parous were at increased risk. Among parous women risk factors included BMI >or= 30, being in a consanguineous marriage, later age at menarche, later age at first full-term pregnancy, high parity and a history of abortion.

CONCLUSION

The risk factors identified for Pakistani women below 45 years were similar to those observed in other studies. However, obesity in pre-menopausal women and late menarche were not protective and consanguinity was identified as a risk.

CONSANGUINEOUS MARRIAGES IN MOROCCO AND THE CONSEQUENCE FOR THE INCIDENCE OF AUTOSOMAL RECESSIVE DISORDERS

Consanguineous marriage is traditionally common throughout Arab countries. This leads to an increased birth prevalence of infants with recessive disorders, congenital malformations, morbidity and mortality. The aim of this study was to evaluate the rate of consanguineous marriage in families with autosomal recessive diseases, and to compare it with the average rate of consanguinity in the Moroccan population. The study was conducted in the Department of Medical Genetics in Rabat on 176 families with autosomal recessive diseases diagnosed and confirmed by clinical, radiological, enzymatic or molecular investigations. The rate of consanguinity was also studied in 852 families who had infants with trisomy 21 confirmed by karyotyping. These families were chosen because: (i) there is no association between trisomy 21 and consanguinity, (ii) these cases are referred from different regions of Morocco and (iii) they concern all social statuses. Among 176 families with autosomal recessive disorders, consanguineous marriages comprised 59.09% of all marriages. The prevalence of consanguinity in Morocco was found to be 15.25% with a mean inbreeding coefficient of 0.0065. The differences in the rates of consanguineous marriages were highly significant when comparing the general population and couples with offspring affected by autosomal recessive conditions. These results place Morocco among the countries in the world with high rates of consanguinity. Autosomal recessive disorders are strongly associated with consanguinity. This study better defines the health risks associated with consanguinity for the development of genetic educational guidelines targeted at the public and the health sector.

Consanguinity in Lebanon: prevalence, distribution and determinants

The union of individuals with a common ancestor may lead to serious health consequences in their offspring. Consanguinity is high in Middle Eastern communities; it was around 26% in 1988. The objective of this study was to determine the prevalence of consanguinity in Beirut and other Lebanese regions, and its associated factors in different subgroups. The cross-sectional study was performed on a convenience sample of married women in Lebanon. The women were administered a standardized questionnaire in a face-to-face interview by independent enquirers. Among 1556 women, the overall prevalence of consanguineous marriages was 35.5%, and the consanguinity coefficient was 0.020; 968 marriages (62.2%) were not consanguineous, 492 (31.6%) were first cousin, 61 (3.9%) were second cousin and 36 (2.3%) had lower degrees of consanguinity. Beirut suburb dwelling, low education subgroups, women working in the home and non-Christian religion presented the highest rates of consanguinity (p<0.05). Consanguinity is associated with couples' nulliparity and child chronic morbidity. Factors that could affect consanguinity are having consanguineous parents, having a favourable opinion towards consanguinity, choosing a spouse for religious reasons, particularly in Islam, woman having a low education, woman working in the home and women thinking that consanguinity would not lead to serious diseases. Consanguinity is therefore still a prevailing problem in Lebanon. Specific health education, and genetic counselling in particular, are suggested to explain the consequences of consanguinity to the general population and to help couples make informed choices.

Decrease in consanguinity among parents of children born in Norway to women of Pakistani origin: a registry-based study

AIMS

To describe the prevalence of consanguinity among Norwegian Pakistani parents in the period from 1995 to 2005.

METHODS

All first births to women of Pakistani origin in 1995-2005 (n = 1962) were identified by linking the Medical Birth Registry of Norway with information on country of origin and country of birth from Statistics Norway. Prevalence ratios (PRs) and prevalence differences were calculated by multiple binomial regression analyses with adjustment for maternal age and education. Women born in Pakistan who gave birth in Norway in 1995-97 formed the reference group.

RESULTS

The proportion of women who were consanguineously related to their co-parent decreased from 45.5% in 1995-97 to 27.3% in 2002-2005 among those who were born in Pakistan, and from 48.3% to 18.8% among women of Pakistani origin who were born in Norway. The proportion of women who were related to their co-parent as first cousin decreased from 37.7% to 24.7% among women born in Pakistan, and from 43.3% to 16.7% among women of Pakistani origin who were born in Norway. The proportion of births to women with an unrelated co-parent increased by 25% for women born in Pakistan (PR = 1.25, 95% confidence interval (CI) = 1.12-1.39), and by 53% for women of Pakistani origin born in Norway (PR = 1.53, 95% CI = 1.35-1.74).

CONCLUSIONS

In contrast to previous reports from the UK, our analysis suggests that there is a decrease in the proportion of consanguineously related parents of children born to women of Pakistani origin in Norway.

Socio-cultural features and sex profile of the individuals with serious suicide attempts in southeastern Turkey: a one-year survey

Our objective was to elucidate potential causes of higher rates of suicide attempts in females compared to males in southeastern Turkey through a 1-year survey. Gender-related differences observed in 96 subjects who attempted suicide by poisoning for the first time were as follows: in comparison to male, females were predominantly within the age interval of 15-24 years, experienced more stressful events in the previous week before suicide attempt, had lower education level, and had a lower rate of employment. One year after the suicide attempt, unfavorable attitude of family, lack of support, persisting unfavorable lifestyle comparable with that prior to the first attempt, and higher rates of domestic violence were more pronounced in females compared to males. These findings might be contributing factors to the higher suicide attempt rates observed in females compared to the males.

Genetic counseling in southern Iran: consanguinity and reason for referral

Population based genetic counseling that promotes public health goals is an appropriate health care service. The genetic counseling center in Shiraz, southern Iran serves most of the clients in the region. During a 4-year period, 2,686 couples presented for genetic counseling. Data files revealed that 85% had consanguineous relationships (1.5% double first cousin, 74% first cousin, 8% second cousin, 1.5% beyond second cousin). Most prevalent reasons for referral were premarital counseling (80%), with 89% consanguinity, followed by preconception (12%), postnatal (7%), and prenatal counseling (1%). The most common abnormalities in probands or relatives were intellectual and developmental disabilities, hearing loss/impairment, and neuromuscular dystrophies. Family history of medical problem(s) and/or consanguinity was the main indication for referral in nearly every family. Premarital consanguinity poses unique challenges and opportunities. There is considerable opportunity for genetic counseling and education for couples in this population. The tradition of consanguinity, which is likely to persist in Iran, requires multidisciplinary agreement regarding the appropriate process of genetic counseling. Effective genetic counseling in Iran hinges on inclusion of data from genetic counseling services in national genomic and epidemiologic research programs.

Premarital screening for thalassemia and sickle cell disease in Saudi Arabia

PURPOSE

To estimate the prevalence of sickle cell disorders and beta thalassemia, with their regional distribution, in the adult population screened as part of the Saudi Premarital Screening Program.

METHODS

A cross-sectional, population-based study was conducted as part of the National Premarital Screening Program. It covered all the individuals who applied for a marriage license during the years 1425 and 1426 Hijra (February 2004 to January 2005). A network of 123 reception centers in the Ministry of Health facilities and 70 laboratories all over Saudi Arabia was involved in data collection.

RESULTS

Of a total of 488,315 individuals screened, 4.20% had sickle cell trait, 0.26% had sickle cell disease, 3.22% had thalassemia trait, and 0.07% had thalassemia disease. Both the diseases were focused mainly in the eastern, western, and southwestern parts of the country. Among the 207,333 couples who were issued certificates for matching, 2.14% were declared high risk. Among the 2,375 high-risk couples contacted by telephone, 89.6% married each other, despite the known high-risk status.

CONCLUSION

The results showed excellent access to the target population. However, the program's objective of decreasing high-risk marriages was not as successful, indicating the need for improvement of health education programs for the public, more efforts in counseling high risk couples, and changes in the strategy of timing of screening in relation to marriage.

Consanguineous unions and child health in the State of Qatar

The aim of the study was to estimate the prevalence and sociodemographic predictors of consanguineous unions in the State of Qatar and to assess the association between consanguinity, fertility and child health. A representative sample of 1800 Qatari women aged > or =15 years was approached for the study. Of these, 1515 (84.2%) women agreed to participate. The consanguineous marriage rate was 54.0% with estimated population confidence limits of 52.3-55.7%. First cousin unions were the most common form of cousin marriage. The level of parental consanguinity (both in the respondent's parents and her parents-in-law) was quite high. In a multivariable analysis, both education of the respondent and her husband as well as parental consanguinity were found to be strong predictors of consanguineous unions in the index generation. Although fertility was high in both groups, the mean number of pregnancies was somewhat higher in respondents with first cousin unions. Concomitantly they also had a slighter higher rate of livebirths than women in non-consanguineous unions. The occurrence of asthma, mental retardation, epilepsy and diabetes was significantly more common in offspring of all consanguineous than non-consanguineous couples.

Proteinuria in South Asian children: prevalence and determinants

Proteinuria in children is a marker of kidney disease and atherosclerosis, both which are known predictors of cardiovascular mortality. Recent evidence suggests that migrant South Asian populations living in the West may be at higher risk of kidney disease than native Caucasians. However, the determinants of proteinuria in South Asian children have not been explored. Previously, we reported ethnic variation in the prevalence of proteinuria in the adult population of Pakistan. However, it is not known whether ethnic predisposition to proteinuria appears during childhood or whether it is acquired later in life as a result of prolonged exposure to undiagnosed diabetes and hypertension. Analyses were based on a subset of data for 4977 children aged 5 to less than 15 years collected as part of the broad National Health Survey of Pakistan, conducted between 1990 and 1994. Proteinuria was defined as a dipstick positive for protein on a random urine sample. Ethnicity was reported as "mother-tongue", which is specific for each of the five major ethnic subgroups of Pakistan: Muhajir, Punjabi, Sindhi, Pashtun, and Baluchi. The overall prevalence (95% CI) of proteinuria in the children was 3.3% (2.7-3.9%). It was 6.2% in Sindhis, 3.6% in Muhajirs, 2.8% in Punjabis, 2.8% in Baluchis, and 1.0% in Pashtuns (p<0.001). In multivariable analyses, proteinuria was associated with greater height (p=0.007), urban dwelling (p=0.03), lower socioeconomic status (p=0.02), and certain ethnicities (p=0.005). The ethnic variation in proteinuria in South Asian children mirrors variation among ethnic groups in adults. This suggests variations in susceptibility or early exposure to causes of chronic kidney disease, rather than long-term exposure to undiagnosed diabetes or hypertension. Further studies are needed to determine factors in early life that may differentially predispose certain ethnic groups to proteinuria.

Endogamy, consanguinity and community disease profiles

Considerable attention is paid to the role of consanguineous marriage as a causative factor in the prevalence of genetic disorders. At the same time, the potential influence of community endogamy on overall levels of homozygosity and disease profiles remains largely under-investigated. With the ongoing global epidemiological transition from infectious to non-communicable disease, the impact of genetic disorders will become increasingly important and a thorough understanding of the determinants of human population-genetic structure will be all the more necessary. In particular, the genetic components of adult-onset diseases will become more obvious and assume greater significance. Similarly, refinements of study design to incorporate intercommunity genetic variation appear to be an essential prerequisite in pharmacogenetic research if the concept of individualized treatments is to achieve reality, with equivalent subject-control comparison difficulties also predicted in forensic genetics.

Consanguineous marriage in Iran

Consanguineous marriage is a major feature of family systems in south-west Asia. The aim of the present study was to determine the current prevalence and patterns of consanguinity in Iran as a means of assessing the associated requirement for genetic counselling services. Consanguinity was studied in 12 ethnic/religious populations, the Persians (Shi'a and Sunni), Kurds (Shi'a and Sunni), Lurs, Azaris, Baluchis, Zabolis, Turkamans, Bakhtiaris, Ghashghais and Arabs. A multi-stage sampling design was used with a representative total sample of 306 343 couples. The overall rate of consanguineous marriage was 38.6% with a mean inbreeding coefficient (alpha) of 0.0185. First cousin marriages (27.9%) were the most common form of consanguineous union, with parallel patrilateral marriage especially favoured. Statistically significant differences were observed in the prevalence and patterns of consanguinity between ethnic/religious populations and geographical regions. There also were significant differences for proportions of consanguineous marriages between Shi'a and Sunni populations within the same ethnic group. The highest rates of consanguineous union were in the least affluent sections of the population.

Ethnic differences and determinants of diabetes and central obesity among South Asians of Pakistan

AIMS

To study the within ethnic subgroup variations in diabetes and central obesity among South Asians.

METHODS

Data from 9442 individuals age > or = 15 years from the National Health Survey of Pakistan (NHSP) (1990-1994) were analysed. Diabetes was defined as non-fasting blood glucose > or = 7.8 mmol/l, or known history of diabetes. Central obesity was measured at the waist circumference. Distinct ethnic subgroups Muhajir, Punjabi, Sindhi, Pashtun, and Baluchi were defined by mother tongue.

RESULTS

The age-standardized prevalence of diabetes varied among ethnic subgroups (P = 0.002), being highest among the Muhajirs (men 5.7%, women 7.9%), then Punjabis (men 4.6%, women 7.2%), Sindhis (men 5.1%, women 4.8%), Pashtuns (men 3.0%, women 3.8%), and lowest among the Baluchis (men 2.9%, women 2.6%). While diabetes was more prevalent in urban vs. rural dwellers [odds ratio (OR) 1.50, 95% confidence interval (CI) 1.24, 1.82], this difference was no longer significant after adjusting for central obesity (OR 1.15, 95% CI 0.95, 1.42). However, the ethnic differences persisted after adjusting for major sociodemographic risk factors (unadjusted OR for Pashtun vs. Punjabi 0.59, 95% CI 0.42, 0.84, adjusted OR 0.54, 95% CI 0.37, 0.78). Ethnic variation was also observed in central obesity, which varied with gender, and did not necessarily track with ethnic differences in diabetes.

CONCLUSIONS

Unmeasured environmental or genetic factors account for ethnic variations in diabetes and central obesity, and deserve further study.

Risk factors for non-fatal myocardial infarction in young South Asian adults

OBJECTIVE

To determine the risk factors for premature myocardial infarction among young South Asians.

DESIGN AND SETTING

Case-control study in a hospital admitting unselected patients with non-fatal acute myocardial infarction.

METHODS AND SUBJECTS

Risk factor assessment was done in 193 subjects aged 15-45 years with a first acute myocardial infarct, and in 193 age, sex, and neighbourhood matched population based controls.

RESULTS

The mean (SD) age of the subjects was 39 (4.9) years and 326 (84.5%) were male. Current smoking (odds ratio (OR) 3.82, 95% confidence interval (CI) 1.47 to 9.94), use of ghee (hydrogenated vegetable oil) in cooking (OR 3.91, 95% CI 1.52 to 10.03), raised fasting blood glucose (OR 3.32, 95% CI 1.21 to 8.62), raised serum cholesterol (OR 1.67, 95% CI 1.14 to 2.45 for each 1.0 mmol/l increase), low income (OR 5.05, 95% CI 1.71 to 14.96), paternal history of cardiovascular disease (OR 4.84, 95% CI 1.42 to 16.53), and parental consanguinity (OR 3.80, 95% CI 1.13 to 1.75) were all independent risk factors for acute myocardial infarction in young adults. Formal education versus no education had an independently protective effect on acute myocardial infarction (OR 0.04, 95% CI 0.01 to 0.35).

CONCLUSIONS

Tobacco use, ghee intake, raised fasting glucose, high cholesterol, paternal history of cardiovascular disease, low income, and low level of education are associated with premature acute myocardial infarction in South Asians. The association of parental consanguinity with acute myocardial infarction is reported for the first time and deserves further study.

Risk factors for neonatal mortality in low-income population subgroups in Karachi, Pakistan

This paper assesses the risk factors for neonatal mortality (0-28 days of life) for full-term singleton live births. The study sample comprised 1,011 ever-married women who were residents of four multi-ethnic, multi-religious low-income areas of Karachi, Pakistan during 1995. The analysis sample was restricted to 4,488 live births to 912 women. Results showed that 4.8% (n = 217) of all births ended in death in the neonatal period, and 76% (n = 164) of these neonatal deaths occurred in the first week of life. While neonatal mortality rates had declined appreciably over time, a large proportion of neonatal deaths were clustered in a small group of women. The univariate analysis showed a statistically significant association between a number of maternal-level parameters (e.g., mother's age at birth, level of formal education, employment status, religious affiliation, and consanguinity) and child-level parameters (e.g., birth order, birth interval, survival status of the preceding child, sex of the neonate, year of death). At the multivariate level, consanguinity, birth order and year of death were found to be statistically significant risk factors for neonatal mortality analyses despite adjustment for death clustering. The study highlights the importance of inbreeding as a determinant of early offspring death, and points to the need for better understanding of why deaths are clustered in certain families. Given the widespread practice of close cousin marriages in Pakistan across all socio-economic groups, there is a need to validate the findings in less economically disadvantaged population subgroups within the country.

Ethnic differences and determinants of proteinuria among South Asian subgroups in Pakistan

BACKGROUND

Hypertension, diabetes, increasing age, and smoking are known risk factors for proteinuria. Prevalence of proteinuria is high in South Asians. However, ethnic subgroup differences and determinants of proteinuria within the South Asian population have not been explored.

METHODS

The National Health Survey of Pakistan conducted between 1990 and 1994 was used to explore ethnic subgroup variation in proteinuria. Distinct ethnic subgroups, the Muhajir, the Punjabi, the Sindhi, the Pashtun, and the Baluchi, were defined by mother tongue. We report results in individuals aged >or=15 years (N = 9442). Proteinuria was defined as dipstick positive for protein on random urine sample.

RESULTS

Increasing age, high consumption of meat, and presence of hypertension and diabetes were each independently associated with proteinuria. The age-standardized prevalence of proteinuria was 4.6% (4.2% to 5.1%) and varied among ethnic subgroups (P < 0.001). The highest was among the Sindhi (men 9.5%, women 10.3%), then the Muhajir (men 8.2%, women 4.7%), the Punjabi (men 3.2% women 3.5%), and lowest among the Baluchi (men 2.4%, women 4.2%) and the Pashtun (men 2.7%, women 1.2%). The ethnic differences persisted after adjusting for the above-mentioned sociodemographic, dietary, and clinical risk factors [adjusted odds ratio (OR) (95% CI)] were 6.42 (3.97 to 10.38) for the Sindhis, 3.58 (2.22 to 5.79) for the Muhajirs, 2.03 (1.25 to 3.29) for the Punjabis, and 1.75 (0.79 to 3.88) for the Baluchis compared to the Pashtuns).

CONCLUSION

We conclude that unmeasured environmental or genetic factors account for ethnic variations in proteinuria, and deserve further study.

Inbreeding coefficients and degree of consanguineous marriages in Spain: a review

The contribution of consanguineous marriages corresponding to uncle-niece or aunt-nephew (C12), first cousin (C22), first cousin once removed (C23), and second cousin (C33) to the inbreeding coefficient (alpha) was analyzed from a sample of Spanish areas and periods. Multiple regressions were performed taking as independent variables the different degrees of consanguinity previously selected (C12, C22, C23, and C33) and as dependent variable the inbreeding coefficient (alpha). According to the results obtained for any degree and period, rural frequencies always surpass urban. However, the pattern is similar in both areas. In the period where consanguinity was more elevated (1890-1929) the C22/C33 ratio increased. Its variation is not due to C22 and C33 changes in the same way. In rural areas, this ratio surpasses the expected value by a factor of 2-3, but in urban areas it was 7-10 times larger, in some cases due to migration. While in rural Spain the C33 frequency was approximately 1.5 times C22, in cities C22 was 1.5 times C33. The best fit among the various types of consanguineous matings and alpha involves a lineal relationship. Regardless of the number of variables contributing significantly to alpha, C22 matings are always present. Moreover, their standardized (beta) coefficients are the highest. The above indicates that this consanguineous relationship conditions the inbreeding coefficient the most. In the period of greater consanguinity, close relationships, uncle-niece C12, and first cousin once removed (C23) make a significant contribution to alpha. In rural Spain second cousins (C33) always significantly determined alpha; however, in cities the inbreeding variation was mainly due to C12 and C23.

Ethnic subgroup differences in hypertension in Pakistan

OBJECTIVE

Cardiovascular risks are globally elevated in South Asians, but this masks important ethnic subgroup differences in risk factors, such as hypertension, which have not been fully explored. We conducted this study to explore the variations in hypertension within ethnic subgroups among South Asians.

DESIGN

Cross-sectional survey [National Health Survey of Pakistan (NHSP) (1990-1994)].

SETTING

Population based.

PARTICIPANTS

A total of 9442 individuals aged 15 years or over.

METHODS

Data on sociodemographic and clinical variables were collected. Distinct ethnic subgroups - Muhajir, Punjabi, Sindhi, Pashtun and Baluchi - were defined by mother tongue.

MAIN OUTCOME MEASURE

Hypertension defined as systolic blood pressure >or= 140 mmHg or diastolic blood pressure >or= 90 mmHg, or currently receiving antihypertensive therapy.

RESULTS

The age-standardized prevalence of hypertension was highest among Baluchis (25.3% in men and 41.4% in women), then Pashtuns (23.7% in men and 28.4% in women), Muhajirs (24.1% in men and 24.6% in women), and lowest among Punjabis (17.3% in men and 16.4% in women) and Sindhis (19.0% in men and 9.9% in women) (P = 0.001). While hypertension was more prevalent in urban (22.7%) versus rural dwellers (18.1%) [odds ratio (OR) 1.34; 95% confidence interval (CI), 1.20, 1.49], this difference was no longer significant after adjusting for body mass and waist circumference (OR 1.03; 95% CI, 0.91, 1.16). However, ethnic differences persisted after adjusting for major sociodemographic, dietary and clinical risk factors (unadjusted OR for Baluchi versus Sindhi, 2.92; 95% CI, 2.20-3.89; adjusted OR, 2.71; 95% CI, 1.97-3.75).

CONCLUSIONS

A threefold difference in prevalence of hypertension exists between people of South Asian descent, which, unlike the urban/rural difference, cannot be accounted for by measured risk factors. Further study would provide valuable etiological and therapeutic clues.

Endogamy, consanguinity and community genetics

The population of India is composed of many thousands of subpopulations, divided by geography, language, religion and caste or biraderi (patrilineage) boundaries, with endogamous marriage the norm. The net effect has been the creation of multiple genetic isolates with individual mutation profiles, but to date the clinical consequences of this highly complex differentiation have been largely ignored. In contrast, the topic of consanguinity continues to attract attention among medical and population geneticists, clinicians and social scientists. The significant progress made in India in improving childhood nutritional status and combating infectious disease means that genetic disorders have assumed ever-increasing importance. In populations where consanguineous marriage is widely practised, recessive genetic disorders will continue to gain greater prominence in the overall spectrum of ill health. At the same time this increase will in part be negated by urbanization and the move to smaller family sizes, which predictably will result in a decline in the prevalence of consanguineous unions. Developing an understanding of these changes will require a wide-ranging and multidisciplinary investigative approach for which community genetics is ideally suited.

Inbreeding and demographic transition in the Orozco Valley (Basque Country, Spain)

Inbreeding in the Orozco Valley (Basque Country, Spain) between the 18th and 20th centuries was investigated on the basis of ecclesiastical dispensations and surname lists. The variations over time are very similar to those observed elsewhere in Europe, with a major increase in the coefficient of inbreeding in the late 19th and early 20th centuries. This is due mainly to an increase in marriages between first cousins. A highly marked decrease in inbreeding is observed during the 20th century. The secular trends described by the coefficient calculated on the basis of dispensations and by that calculated on isonymy are very similar. The nonrandom component of isonymy reveals a selective search for a related spouse during the period of maximum inbreeding. These results are associated with the process of demographic transition which affected European populations as a whole in the 19th century, resulting in a greater availability of kin among potential mates and thus enabling inbreeding to increase to levels far higher than those observed for earlier centuries.

Science and society: genetic counselling and customary consanguineous marriage

Consanguineous marriage is customary in many societies, but leads to an increased birth prevalence of infants with severe recessive disorders. It is therefore often proposed that consanguineous marriage should be discouraged on medical grounds. However, several expert groups have pointed out that this proposal is inconsistent with the ethical principles of genetic counselling, overlooks the social importance of consanguineous marriage and is ineffective. Instead, they suggest that the custom increases the possibilities for effective genetic counselling, and recommend a concerted effort to identify families at increased risk, and to provide them with risk information and carrier testing when feasible.

Lay perceptions of genetic risks attributable to inbreeding in Pakistan

Pakistan along with many other West and South Asian countries has a very high prevalence of consanguineous, especially close cousin, marriages. Although there is substantial empirical information on offspring morbidity and mortality attributable to parental consanguinity, population-based information on how communities in general, and women in particular, perceive the health risks associated with consanguineous unions is limited. This paper considers community perceptions of health effects associated with consanguineous marriages using qualitative data from 15 focus group discussions and 294 in-depth interviews. The study was conducted in four low-income, multi-ethnic, and multi-religious communities in Karachi, the principal commercial center of Pakistan. The results show a general lack of awareness of the possible adverse health effects of consanguineous marriage. In cases where a link between consanguinity and ill health was acknowledged, it often centered on the familial origins of non-communicable disorders such as diabetes and hypertension or infectious diseases such as tuberculosis. Belief in fate and the "evil eye" was widespread across all ethnic and religious groups. Many respondents did not agree with medical explanations of a genetic mode of disease inheritance, even in cases where there was an affected child in the family. The absence of a uniform manifestation of disease among all children of a couple who were identified as carriers of a specific mutation added to the confusion among participants. The study highlights the need for further quantification of risks associated with consanguinity and a need for provision of appropriate information to primary-care clinicians and also to communities. The likely impact of increasing morbidity attributable to inbreeding on the health care system in resource poor settings is also discussed.

An insight into recent consanguinity within the Basque area in Spain. Effects of autochthony, industrialization and demographic changes

BACKGROUND

The importance of studying the genetic kinship of those human groups characterized by a deeply rooted ethnicity has traditionally been and still is an interesting goal of anthropological and population genetic studies. However, only a few surveys have aimed to learn about the impact of industrial development on the consanguinity of these populations and even those have concentrated on industrialized regions. This approach is worth analysing in Spain, where industrialization was late in relation to other western European countries.

AIM

In this work we analyse the characteristics of inbreeding in Guipúzcoa from 1951 to 1995. This Basque province underwent industrial and tourist development earlier than other Spanish regions. It has the highest density of Basque speakers and has always occupied a central position within the map of distribution of the Basque language. Guipúzcoa is geographically placed in the core of the Basque area. SUDJECTS AND METHODS: Data on consanguineous marriages recorded in the province of Guipúzcoa between 1951 and 1995 were taken from Roman Catholic dispensations stored in the Diocesan Archives of San Sebastián, the province's capital city. Over the whole time period, a total of 1152 consanguineous marriages were registered.

RESULTS

The high frequencies of first cousin (M22) (F = 1/16) and uncle-niece, aunt-nephew (M12) (F = 1/8) consanguineous marriages distinguish Guipúzcoa from the rest of Iberian populations. The M22/M33 ratio (with M33 being second cousins) has never dropped below 0.67, which represents a significant deviation from the expectation value of 0.25. When consanguineous marriages are classified according to marriage partner birthplaces interesting results emerge. Provincial endogamy shows the highest consanguinity rates (57%) and the proportion of M22/M33 is also rather high (0.63). However, a major contribution to the consanguinity levels and mean inbreeding coefficient recorded in Guipúzcoa over recent decades has been made by immigrant relative groups coming from other geographical areas of Spain. In this segment of population the observed M22/M33 rates are 1.44.

CONCLUSIONS

This study shows again how important preferentiality (or avoidance) is in human consanguinity, and also how human groups, in spite of being spatially settled in the same territory, present differential attitudes for given consanguinity patterns.

Consanguinity and its relevance to clinical genetics

Marriage between close biological relatives is generally regarded with suspicion and distaste within Western society, reflecting historical and religious prejudice. By comparison, in many other populations there is a strong preference for consanguineous unions, most frequently contracted between first cousins, and marriage outside the family is perceived as a risky and disruptive option. The increasing importance of the genetic contribution to the overall disease profile in both developed and developing countries has highlighted potential problems associated with detrimental recessive gene expression in consanguineous progeny. This review examines the outcomes of consanguineous unions, with proposals as to how the ongoing preference for consanguinity in many communities can best be accommodated from a clinical genetics perspective.