Consanguinity as a determinant of reproductive behaviour and mortality in Pakistan

A critical systematic review and meta-analyses of risk factors for fertility problems in a globalized world

Globally, fertility awareness efforts include well-established risk factors for fertility problems. Risks disproportionately affecting women in the Global South, however, are neglected. To address this gap, we conducted a systematic review and meta-analyses of relevant risk factors to examine the association between risk factors and fertility problems. MEDLINE, Embase, Cochrane Library, regional databases and key organizational websites were used. Three authors screened and extracted data independently. Studies assessing exposure to risk (clinical, community-based samples) were included, and studies without control groups were excluded. Outcome of interest was fertility problems, e.g. inability to achieve pregnancy, live birth, neonatal death depending on study. The Newcastle-Ottawa Scale was used to assess study quality. A total of 3843 studies were identified, and 62 were included (58 in meta-analyses; n = 111,977). Results revealed the following: a ninefold risk of inability to become pregnant in genital tuberculosis (OR 8.91, 95% CI 1.89 to 42.12); an almost threefold risk in human immunodeficiency virus (OR 2.93, 95% CI 1.95 to 4.42) and bacterial vaginosis (OR 2.81, 95% CI 1.85 to 4.27); a twofold risk of tubal-factor infertility in female genital mutilation/cutting-Type II/III (OR 2.06, 95% CI 1.03 to 4.15); and postnatal mortality in consanguinity (stillbirth, OR 1.28, 95% CI 1.04 to 1.57; neonatal death, OR 1.57, 95% CI 1.22 to 2.02). It seems that risk factors affected reproductive processes through multiple pathways. Health promotion encompassing relevant health indicators could enhance prevention and early detection of fertility problems in the Global South and disproportionately affected populations. The multifactorial risk profile reinforces the need to place fertility within global health initiatives.

Consanguineous Marriage and Its Association With Genetic Disorders in Saudi Arabia: A Review

Consanguineous marriages, where spouses are related by blood, have been a longstanding practice in human history. The primary medical concern with consanguineous marriages is the increased risk of genetic disorders. When closely related individuals reproduce, there is a higher probability that both parents carry the same genetic mutation. In Arab countries, especially Saudi Arabia, the rate of consanguineous marriage is high compared with Western European and Asian countries. This high rate is directly proportionate with elevated risk of genetic disorders, including congenital heart diseases, renal diseases, and rare blood disorders. Additionally, it was noted that the rate of negative postnatal outcomes is higher in consanguineous marriages compared with the general population. These observations indicate the necessity of tackling this area and highlighting the consequences of this practice. In this review, we aim to discuss the current evidence regarding the association between consanguineous marriages and genetic disorders in Saudi Arabia.

Prevalence and socio-economic determinants of consanguineous marriages in Algeria according to Multiple Indicator Cluster Survey 2019 data (MICS6)

Consanguineous marriage is still a customary social phenomenon in Arab-Muslim communities. The aim of this study was to estimate the prevalence of consanguineous marriages in the Algerian population and to identify the socio-economic determinants associated with the practice of this form of union. This is a descriptive cross-sectional study included data for 21141 ever-married women aged 15-49 years, from the MICS6 Algeria (Multiple Indicator Cluster Survey database), conducted in 2019. Using a logistic regression model, we assessed the influence of socio-economic and geographical determinants on the practice of consanguineous marriages. The prevalence of consanguinity was 23.0% (95% CI: 22.4-23.6). According to multivariable binary logistic regression analysis, low level of education, early age at marriage (15-19; 20-30 years), rural area of residence, all geographical regions except the north-western territorial programming space, economic activity, and the lowest wealth index were the main determinants that assist in the prevalence of high rates of consanguineous marriages in Algeria. Considering these explanatory variables could help national health policy decision-makers to create and implement national preventive action plans that are intended alter behaviors attitudes toward preference of consanguineous marriages and, thus, reduce the burden of genetic disorders or congenital abnormalities associated with consanguinity.

Consanguinity, inbreeding coefficient, fertility and birth-outcome in population of Okara district, Pakistan

Objectives

This study was aimed to illustrate the determents of consanguinity and inbreeding coefficient-F (ICF) in the population of Okara district of Pakistan and to elucidate the impact of consanguinity on fertility and birth outcome.

Methods

Through a cross-sectional sampling design, 1,521 married women were recruited from Okara district during 2016-2017. Data on demographic variables, marital union types, subject's fertility, and reproductive outcome, were gathered in face-to-face interviews. Descriptive statistics and multivariable logistic regression were employed.

Results

The prevalence of consanguineous unions (CU) was calculated to be 61% yielding ICF=0.0356. Multivariable regression analyses revealed that six variables including younger age at marriage, joint family structure, caste-system of spouse, exchange marriage, matrimonial distance, and parental consanguinity, were significant predictors of consanguinity. The women having CU had significantly higher mean fertility, mean live-births and mean live-born sons compared with subjects having non-consanguineous unions (NCU). However, there were no significant differences in the average mortalities, i.e., prenatal, postnatal and <5 years, between the mothers with CU and NCU.

Conclusion

The prevalence of consanguineous unions (CU) in Okara district is quite high like other inbred populations of Pakistan. The striking findings of this study are the higher mean fertility and mean live-births in women with CU. The likely reasons underlying this phenomenon have been discussed.

Prevalence and pattern of consanguineous marriage among educated married individuals in Riyadh

Consanguineous marriage is preferred in many countries, especially by Muslims. Despite the increasing education rate in Saudi Arabia, the prevalence of consanguineous marriage does not seem to be decreasing as quickly as expected. The present study aimed to investigate the current prevalence of consanguineous marriage among educated married adults in Riyadh and to determine the factors favouring it. The cross-sectional study was conducted in 2017-18 using an online questionnaire. A total of 550 questionnaires were sent to married adults of both sexes and 417 responded, giving a response rate of 75.8%. The questionnaire consisted of two parts: the first section asked for demographic data such as age, sex, educational level, residential area and family size. The second part was about consanguineous marriage and its degree if present, family history of consanguineous marriage and level of awareness of its potential negative impact on offspring. It was found that the prevalence of consanguineous marriage among the participating educated adults was 39.8% and most of these were married to a first cousin. Neither level of education nor age affected the likelihood of consanguineous marriage, but predictors for the practice among the educated participating adults were having a family history of consanguineous marriage, having consanguineous parents and having a personal preference for consanguineous marriage. In conclusion, the prevalence of consanguineous marriage among educated adults in Riyadh was still high in 2018, especially among first-cousin relatives, and this was related to family history and personal preference rather than educational level or age. It is recommended that further research is conducted to assess the level of knowledge about, and attitude towards, consanguineous marriage among adults in Saudi Arabia.

Hemoglobinopathies in the North of Morocco: Consanguinity Pilot Study

Consanguinity is a social behavior characterized by the arrangement of marriages between relatives. It coincides generally with the geographic distribution of recessive genetic diseases as it increases the likelihood of homozygosis and, consequently, the incidence of their pathologies in the population. In this pilot study, we assess the effect of inbreeding on the burden of hemoglobinopathies in Northern Morocco. From January 2016 to December 2018, 197 children born in the studied region to three ancestral generations and diagnosed with hemoglobinopathies were subject to investigation. The rate of consanguinity in the parents' generation of children with hemoglobinopathies was 50.25%, with first cousin marriages accounting for 68.69% of consanguineous unions (FI = 0.02). The corresponding rates in the general population, based on a sample of N = 900, were 29.67% and 82.02%, respectively. The marriages between first cousins are the most common among the other types of consanguineous unions. Our study propounds that consanguinity substantially contributes to the hemoglobinopathy burden in the studied region and has changed little over time. Refraining from consanguineous marriages and detecting couples at risk could contribute to the reduction of the incidence of genetic diseases in our country.

A review of the reproductive consequences of consanguinity

BACKGROUND

Consanguinity is the close union, sexual relationship or marriage between persons who have common biological ancestors usually up to about 2nd cousins. Contrary to general opinion consanguinity is quite common and is practiced worldwide. It is an important topic as while rates of consanguineous unions in certain society have decreased over time, rates have remained stable or increased in other societies with rates as high as 80.6% in some communities. Our aim was to conduct a review looking at general aspects of consanguinity and any published reproductive outcomes in literature. We also looked at possible future directions that could be relevant in the management of the consanguineous couple to help improve reproductive outcomes.

METHOD

We conducted a PUBMED, CINAHL, Web of Knowledge and Google Scholar search looking at articles on consanguinity. Consanguinity articles related to pregnancy and reproduction were searched using additional filters looking at our specific areas of interest. All relevant publications up to March 2015 were reviewed. Additional search for relevant articles pertaining to pre implantation genetic diagnosis for future directions in the management of the consanguineous couple was done. Most publications were found in books, on line articles and journals. Most were retrospective, population or cohort studies.

RESULT

Consanguinity is practiced by up to 10% of the world's population with rates ranging from 80.6% in certain provinces in the Middle East to less than 1% in western societies. It predates Islam and has been practiced since Old Testament times. The most commonly cited reason for consanguinity is sociocultural and socioeconomic although it is also more common in certain religions. In areas where rates of Consanguinity are reducing urban migration and increasing education rates are thought to be contributory. Congenital malformations have long been established to be higher in consanguineous couples above the background rate (4.5% Vs 1%).Due to "Founder effect" or a common ancestor, Consanguinity is most commonly associated with Inborn errors of metabolism most of which are autosomal recessive. Consanguinity increases the incidence of multifactorial disorders such as diabetes, cardiovascular disorders, obesity and certain types of cancers. These may in turn affect reproductive outcomes. It may also affect fertility rates. Pregnancy outcomes like increased pregnancy wastages and preterm labor have been reported with consanguinity. Other studies produced conflicting evidence on its effect regarding outcomes like hypertensive disorders of pregnancy and Intrauterine growth restriction.

CONCLUSION

Consanguinity continues to be practiced worldwide and in some countries rates are increasing. The main reason for the practice appears to be sociocultural and socioeconomic although religious beliefs is a contributory factor. The most significant effects on reproductive outcomes are mostly due to autosomal recessive inherited conditions and inborn errors of metabolism. It also significantly increases the inheritance of certain multifactorial disorders like diabetes which may indirectly affect reproductive outcomes. In the future with the completion of the study of the whole human Genome and current advances in Pre implantation Genetic diagnosis and screening it may be possible to mitigate some of the adverse reproductive outcomes associated with consanguinity.

Understanding the consumption of folic acid during preconception, among Pakistani, Bangladeshi and white British mothers in Luton, UK: a qualitative study

Background

To review the similarities and differences in Pakistani, Bangladeshi and White British mothers health beliefs (attitudes, knowledge and perceptions) and health behaviour regarding their consumption of folic acid pre-conception, to reduce the risk of neural tube defects.

Methods

Our study used a descriptive qualitative research approach, implementing face-to-face focus group discussions with Pakistani, Bangladeshi or White British mothers (normal birth outcomes and mothers with poor birth outcomes) and semi-structured interviews or focus groups with service providers using semi-structured topic guides. This method is well suited for under researched areas where in-depth information is sought.

There were three sample groups:

Pakistani, Bangladeshi and White British mothers with normal birth outcomes (delivery after 37 weeks of gestation, in the preceding 6 to 24 months, weighing 2500 g and living within a specified postcode area in Luton, UK).

Pakistani Bangladeshi and white British bereaved mothers who had suffered a perinatal mortality (preceding 6 to 24 months, residing within a specificied postcode area).

Healthcare professionals working on the local maternity care pathway (i.e. services providing preconception, antenatal, antepartum and postpartum care).

Transcribed discussions were analysed using the Framework Analysis approach.

Results

The majority of mothers in this sample did not understand the benefits or optimal time to take folic acid pre-conception. Conversely, healthcare professionals believed the majority of women did consume folic acid, prior to conception.

Conclusions

There is a need to increase public health awareness of the optimal time and subsequent benefits for taking folic acid, to prevent neural tube defects.

Electronic supplementary material

The online version of this article (10.1186/s12884-018-1884-0) contains supplementary material, which is available to authorized users.

Determinants of consanguinity and inbreeding coefficient in the multiethnic population of Mardan, Khyber Pakhtunkhwa, Pakistan

Background

Despite the high sociocultural preferences in contracting marriages among close relatives in Pakistan, marked regional differences exist in the prevalence of consanguinity. There is great interest to elucidate the sociodemographic variables underlying the heterogeneity in consanguinity prevalence in the various populations. The present study was conducted in the Mardan district of Pakistan, the second largest multiethnic Pashtun metropolis.

Objective

To find determinants of consanguineous unions.

Methods

In a cross-sectional study design, a convenience sample of 1,202 ever-married men from 3 tehsils of Mardan district was recruited in an unselected manner and data regarding their marital union types and sociodemographic variables were obtained by a structured interview. Descriptive statistics and multivariable logistic regression analyses were used.

Results

Consanguineous unions accounted for 44% of all marriages, and the inbreeding coefficient was calculated as 0.0258. Regression analyses revealed that 6 variables were significant predictors of consanguinity, namely, tehsil, age, year of marriage, caste (zaat/biradari) system, area of house, and marriage arrangement of the respondent, while 6 other variables, namely, rural/urban origin, literacy, occupation, monthly income, household type, and number of family members, were not found to be significant. Regression analyses showed that there were different combinations of variables predictive of consanguinity among the various tehsils.

Conclusions

The prevalence of consanguinity in the Mardan district was found to be lower than that in many other districts of Pakistan. National regional differences exist in consanguinity, and the combination of predictive factors varies greatly.

CONSANGUINEOUS MARRIAGES AMONG IRANIAN MANDAEANS LIVING IN SOUTH-WEST IRAN

Several studies have indicated that consanguineous marriages (unions between biologically related persons) are associated with increased risk of autosomal recessive diseases and several multifactorial traits. Mandaeans are a closed ethno-religious community living in areas of southern Iraq and Iran (Khuzestan Province). There are currently no data on the prevalence of consanguineous marriages among Mandaeans. The present study was carried out in 2016 to determine the prevalence of consanguinity among Iranian Mandaeans living in Khuzestan Province, south-west Iran. A total of 137 couples (urban areas: 79 couples; rural areas: 58 couples) were included in the study. Information on the consanguineous marriages of the subjects was collected through direct interviews. Marriages were classified by the degree of relationship between couples as double first cousins, first cousins, first cousin once removed, second cousins and unrelated marriages. The coefficient of inbreeding (F) was calculated for each couple and the mean coefficient of inbreeding (α) estimated for the population, stratified by rural and urban areas. The overall frequency of consanguinity was found to be 50.7% in urban and 86.2% in rural areas. There was a significant difference between rural and urban areas in types of marriages (χ 2=24.8, df=4, p<0.001) and first cousin marriages (51.8%) were the most common type. The overall α-value was estimated to be 0.0363 for the Iranian Mandaean population.

Classic Case Report of Donohue Syndrome (Leprechaunism; OMIM *246200): The Impact of Consanguineous Mating

Donohue syndrome ([DS]; leprechaunism) describes a genetic autosomal recessive disorder that results from the presence of homozygous or compound heterozygous mutations in the insulin receptor gene (INSR; 19p13.3-p13.2).Donohue syndrome is associated with a fatal congenital form of dwarfism with features of intrauterine and postnatal growth retardation, exaggerated hyperglycemia with hyperinsulinism and dysmorphic abnormalities.We present a case of DS owing to the rarity of this syndrome (1 case in every million births). We discuss how the disease presents, its genetic underpinning, and its prevention.The case was encountered in an Arab male born on 1 September, 2014, for consanguineous parents. The delivery was via cesarean section at 37 weeks gestation due to severe intrauterine growth restriction and nonprogress labor term. The patient was admitted to the Neonatal Intensive Care Unit due to infection, and jaundice. Dysmorphic features, abnormalities of the craniofacial region, low birth weight, skin abnormalities, abdominal distension and hypertrichosis were observed. Laboratory examinations showed, hyperinsulinism, increased C-peptide, thrombocytopenia, leucopenia, and anemia.The diagnosis of DS was done based on the combinations of typical dysmorphic characteristics, clinical evaluation, supported by genetic analysis and exaggerated biochemical results. Genetic diagnosis of DS was performed through analysis of DNA via polymerase chain reaction (PCR). A qualitative real-time PCR was used, to monitor the amplification of a targeted DNA molecule during the PCR. Other technique using sequencing of the INSR gene, which permits genetic diagnosis, counseling, and antenatal diagnoses in subsequent pregnancies, were also performed.Treatment of DS is supportive and requires the combined efforts of a multidisciplinary team, which include pediatricians, endocrinologists, dermatologists, and other health care professionals. Currently, treatment with recombinant insulin-like growth factor 1 demonstrates effectiveness, and a combination treatment with insulin-like growth factor binding protein 3 resulted in an increased lifespan.There is a scarcity of genetic information on DS among the Arab population. Consanguinity is one of underlying reasons for the appearance of rare genetic disorders. Inbreeding has long been considered a controversial phenomenon. Genetic counseling and overwhelming the alertness of the negative consequences of consanguinity on public health are warranted.

UK Pakistani views on the adverse health risks associated with consanguineous marriages

This is a qualitative study exploring the perceptions of members from the Pakistani/Kashmiri community living in Luton, UK, on the adverse health risks associated with consanguineous marriages. Rates of stillbirths and infant mortality are higher than the national average in Luton and the existing evidence base suggests that these higher rates may be associated with consanguinity (especially first cousin marriages) in highly consanguineous populations, such as the Pakistani/Kashmiri ethnic group. This qualitative study included 9 focus groups and 10 one to one in-depth interviews (n = 58) with members from the Pakistani/Kashmiri community in Luton during 2012. Audio-recorded transcripts were analysed using framework analysis. Emerging themes included a limited knowledge, opposition to evidence and need for a more culturally sensitive health services approach. Findings from the focus group and interview discussions indicated that participants had a limited and varied understanding of genetic risk and indicated a lack of discussion within the community regarding genetic risk. They also opposed evidence that may link consanguineous marriages with infant mortality, stillbirth or genetic disorders that led to disability. The participants stressed the need for culturally sensitive and locally constructed services for information on genetic risk and services. These findings may be used to address higher rates of infant mortality and adverse health impacts associated with higher rates of consanguinity in Luton and elsewhere, through a partnership approach, improve upon current services and develop culturally appropriate services.

CONSANGUINITY AND INBREEDING COEFFICIENT IN TRIBAL PASHTUNS INHABITING THE TURBULENT AND WAR-AFFECTED TERRITORY OF BAJAUR AGENCY, NORTH-WEST PAKISTAN

The north-western populations of Pakistan in the Federally Administered Tribal Areas (FATA) adjoining the Pakistan–Afghanistan border are an amalgamation of native and migrated Pashtun tribes. These tribal populations are in transition due to war conditions and geo-political turmoil on both sides of the border since the Soviet invasion in 1979. Bio-demographic and epidemiological data for these tribes are scarce. A prospective cross-sectional sample of 967 males was selected from a representative Pashtun population of Bajaur Agency, and information obtained on bio-demographic variables and marital union types. Analysis of these data revealed that consanguinity was 22.34% and the inbreeding coefficient F was calculated to be 0.0134. The inbreeding coefficient was observed to be higher in subjects who were illiterate, had unskilled jobs and who belonged to younger age categories, extended families and the Tarkalani tribe. Further analyses with respect to temporal variables like subject's age, year of marriage and age at marriage revealed that after a transition in marital union types in the early 80s, there has been a declining trend in the rate of consanguineous unions. Further, consanguineous unions in the parental generation were only 5%, but parental marriage types were predictors of subjects' marital union types. The data further establish that, contrary to a general notion about a high consanguinity rate in Pakistan, consanguineous unions are not common in Bajaur Agency and first cousin marriage is not the preferred type. Furthermore, this research shows that there is a great regional variation in the pattern of consanguinity in Pakistan that needs to be documented in order to draw a more comprehensive picture of the inbreeding coefficient in the country.

PATTERN OF CONSANGUINITY AND INBREEDING COEFFICIENT IN SARGODHA DISTRICT, PUNJAB, PAKISTAN

Consanguinity is widespread in Pakistan. The majority of studies on consanguinity in Pakistan have been carried out in urban metropolitan areas, and data on rural populations are scarce. The present cross-sectional study was conducted in Sargodha district, upper Punjab, Pakistan where the majority of the population reside in rural areas. A random sample of 1800 married females belonging to six tehsils of Sargodha district was obtained and differentials in consanguinity rates and inbreeding coefficient (F) were investigated. The consanguinity rate was calculated to be 56.72% and the inbreeding coefficient was 0.0348. First cousin unions had the highest representation (49.11% of all marriages), and marriages up to distantly related/Biradari constituted 67.94% of all marriages. Among the six tehsils, consanguinity rates ranged from 50.38% in Bhalwal to 62.88% in Sillanwali. A high rate of consanguinity was observed in subjects speaking the Punjabi language, those with self-arranged/arranged-love marriages and those engaged in professional jobs. With respect to the occupation of husbands the highest consanguinity rate was found among landowners (77.59%; F=0.0539) and businessmen (62.62%; F=0.0377). However, consanguinity did not appear to be associated with rural/urban origin or literacy level. The data showed a wide variation in consanguinity rate and inbreeding coefficient across socio-demographic strata in the Sargodha district population. A comparison of Sargodha with other populations of Punjab also showed regional heterogeneity in the pattern of consanguinity, warranting further studies.

CIVIL UNREST AND THE CURRENT PROFILE OF CONSANGUINEOUS MARRIAGE IN KHYBER PAKHTUNKHWA PROVINCE, PAKISTAN

Information on the current prevalence and types of consanguineous marriages in Malakand District, Khyber Pakhtunkhwa Province (KPK), Pakistan, was collected from 1192 rural couples. Some 66.4% of marriages were between couples related as second cousins or closer (F≥0.0156), equivalent to a mean coefficient of inbreeding (α) of 0.0338. The data suggest that the prevalence of consanguineous unions in Malakand has been increasing during the last decade, in response to the high levels of violence across KPK.

A positive association between consanguinity and fertility in communities of Paraíba, Northeast Brazil

BACKGROUND

Consanguinity of human populations can but does not have to be associated with increased fertility. A recent study involving communities of Northeast Brazil revealed increased levels of endogamy.

SUBJECTS AND METHODS

Data from 20 451 interviewed couples and their 74 289 children were analysed.

AIM

The present study aimed to compare fertility between consanguineous and unrelated couples of these communities.

RESULTS

Consanguineous and unrelated couples of the 39 communities had an average of 4.3 (SD = 0.9) and 3.5 (SD = 0.8) children (p < 0.0001), respectively. Average offspring number of consanguineous couples varied from 3.9 (SD = 1.1) to 5.6 (SD = 3.4) for couples related at the level of third cousins and double first cousin/uncle-niece, respectively (p < 0.005). The correlation coefficient between Human Development Index and fertility was -0.38 (p = 0.0179) and -0.23 (p = 0.17) for unrelated and related couples, respectively.

CONCLUSION

Results indicated an overall positive association between consanguinity and fertility. Fertility tended to be increased, for closely related couples, compared to those related more distantly.

Risk factors predisposing to congenital heart defects

Introduction:

Congenital heart disease (CHD) is associated with multiple risk factors, consanguinity may be one such significant factor. The role of consanguinity in the etiology of CHD is supported by inbreeding studies, which demonstrate an autosomal recessive pattern of inheritance of some congenital heart defects. This study was done to find out the risk factors for CHD.

Methods:

A case-control study was done on pediatric patients at a tertiary care hospital, Aga Khan University Hospital, located in Karachi, Pakistan. A total of 500 patients, 250 cases and 250 controls were included in the study.

Results:

Amongst the 250 cases (i.e. those diagnosed with CHD), 122 patients (48.8%) were born of consanguineous marriages while in the controls (i.e. non-CHD) only 72 patients (28.9%) showed a consanguinity amongst parents. On multivariate analysis, consanguinity emerged as an independent risk factor for CHD; adjusted odds ratio 2.59 (95% C. I. 1.73 - 3.87). Other risk factors included low birth weight, maternal co-morbidities, family history of CHD and first born child. On the other hand, medications used by the mother during the index pregnancy, maternal age and gender of the child did not significantly increase the risk of developing CHD.

Conclusions:

Analyses of our results show that parental consanguinity, family history of CHD, maternal co-morbidities, first born child and low birth weight are independent risk factors for CHD.

Prevalence of consanguineous marriages in west and south of Afghanistan

The prevalence of consanguinity in eight provinces of Afghanistan has recently been reported by Saify & Saadat (2012). The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among other populations of Afghanistan. Data on types of marriages were collected using a simple questionnaire. The total number of couples in this study was 5200 from the following provinces: Farah, Ghazni, Herat, Hilmand, Kabul, Kandahar, Logar, Parwan and Wardak. Consanguineous marriages were classified by the degree of relationship between couples: double first cousins, first cousins, first cousins once removed, second cousins and beyond second cousins. The coefficient of inbreeding (F) was calculated for each couple and the mean coefficient of inbreeding (α) estimated for each population. The α in the country was 0.0226, ranging from 0.0203 in Farah province to 0.0246 in Herat province. There were significant differences between provinces for frequencies of different types of marriages (p<0.001). First cousin marriages (21.7%) were the most common type of consanguineous marriages, followed by second cousins (16.0%), first cousins once removed (14.0%), beyond second cousins (6.9%) and double first cousins (1.6%). There was significant difference between ethnic groups for the types of marriages (p<0.001). Tajiks (Soni) and Sadats showed the lowest (α=0.0215) and highest (α=0.0242) levels of consanguinity among ethnic groups in Afghanistan, respectively. The present study shows that the Afghani populations, the same as other Islamic populations, have high levels of consanguinity.

TYPES OF MARRIAGES, POPULATION STRUCTURE AND GENETIC DISEASE

A high occurrence rate of consanguineous marriages may favour the onset and increased frequency of autosomal recessive diseases in a population. The population of Monte Santo, Bahia, Brazil, has a high frequency of rare genetic diseases such as mucopolysaccharidosis type VI, whose observed frequency in this population is 1:5000, while the incidence of this disease recorded in other regions of the world varies from 1:43,261 in Turkey to 1:1,505,160 in Switzerland. To verify the influence of consanguineous marriage on the increased frequency of observed genetic diseases in this population, the population structure and frequency of different types of marriage during different time periods were evaluated. A total of 9765 marriages were found in an analysis of parish marriage records from the city. Over three periods, 1860–1895, 1950–1961 and 1975–2010, the inbreeding rates were 37.1%, 13.2% and 4.2% respectively. Although there was a high rate of inbreeding, endogamic marriages were the dominant marriage type in all three periods. In the most recent period, there was an increase in the number of exogamous marriages and those among immigrants, but most of these occurred among individuals from cities that neighbour Monte Santo. The low rate of migration and high frequency of endogamic and consanguineous marriages show that growth of this population is predominantly internal and could explain the occurrence, and increase in frequency, of recessive genetic diseases in the city.

Cousin marriage in south-western England in the nineteenth century

Knowledge of inbreeding levels in historical times is necessary to estimate the health consequences of past inbreeding, and to contextualize the current public debate about cousin marriage in Britain. This research aims to calculate the level of cousin marriage using the intensive technique of multi-source parish reconstitution and to determine whether village organization, religion and occupational class influenced the level of consanguineous marriage. A wide variety of documentary sources were used to create extensive pedigrees of spouses in over 800 marriages in the 19th century in the rural villages of Stourton and Kilmington. The closed village of Stourton had higher levels of inbreeding than the open village of Kilmington. Catholics had lower rates of 1st cousin marriage but higher rates of 2nd cousin marriage than Protestants. Farmers had higher levels of 1st cousin marriage than labourers. The levels of consanguinity in south-western Wiltshire in the 19th century were related to the economic structure of the villages and the religion and social class of the spouses.

The practice of consanguineous marriage in Oman: prevalence, trends and determinants

The practice of consanguineous marriage has been the culturally preferred form of marriage in most Arab and the Middle Eastern countries, including Oman, but due to a paucity of population-based data in the past there is a dearth of information about its form and dynamics in Oman. Recent national-level surveys allow this gap to be filled. This paper examines the prevalence, trends and determinants of consanguineous marriages in Oman using data from the 2000 Oman National Health Survey. The results indicate a very high prevalence of consanguineous marriage in Oman, as more than half (52%) of marriages are consanguineous. First cousin unions are the most common type of consanguineous unions, constituting 39% of all marriages and 75% of all consanguineous marriages. The study observed various patterns of consanguinity, some of them common with other Arab nations, and some unique in nature. Women's age at marriage, employment, place of childhood residence and geographical region appear to be significant determinants of consanguineous marriages. Consanguineous marriage shows a strong association with marital stability, early age at marriage and early-age childbearing. There has been no appreciable change in the prevalence of consanguineous unions in Oman over the last four decades despite massive socioeconomic development and modernization. However, recent marriage cohorts show slight declining trends. The results suggest that consanguinity is likely to remain stable in the future or decline at a slow rate. Specific health education and genetic counselling should be followed in line with WHO recommendations to minimize the negative health consequences of consanguinity for child health.

Assessing the influence of consanguinity on congenital heart disease

Numerous articles have been published linking consanguineous marriage to an elevated prevalence of congenital heart disease, with ventricular septal defects and atrial septal defects the most commonly cited disorders. While initially persuasive, on closer examination many of these studies have fundamental shortcomings in their design and in the recruitment of study subjects and controls. Improved matching of cases and controls, to include recognition of the long-established community boundaries within which most marriages are contracted, and the assessment of consanguinity within specific levels and types of marital union would improve and help to focus the study outcomes. At the same time, major discrepancies between studies in their reported prevalence and types of congenital heart disease suggest an urgent need for greater standardization in the classification and reporting of these disorders.

CONSANGUINEOUS MARRIAGES IN AFGHANISTAN

The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among Afghanistan populations. Data on types of marriages were collected using a simple questionnaire. The total number of couples in the study was 7140 from the following provinces: Badakhshan, Baghlan, Balkh, Bamyan, Kabul, Kunduz, Samangan and Takhar. Consanguineous marriages were classified by the degree of relationship between couples: double first cousins, first cousins, first cousins once removed, second cousins and beyond second cousins. The coefficient of inbreeding (F) was calculated for each couple and the mean coefficient of inbreeding (α) estimated for each population. The proportion of consanguineous marriages in the country was 46.2%, ranging from 38.2% in Kabul province to 51.2% in Bamyan province. The equivalent mean inbreeding coefficient (α) was 0.0277, and ranged from 0.0221 to 0.0293 in these two regions. There were significant differences between provinces for frequencies of different types of marriages (p<0.001). First cousin marriages (27.8%) were the most common type of consanguineous marriages, followed by double first cousin (6.9%), second cousin (5.8%), beyond second cousin (3.9%) and first cousin once removed (1.8%). There were significant differences between ethnic groups for the types of marriages (χ2=177.6, df=25, p<0.001). Tajiks (Soni) and Turkmens (also Pashtuns) showed the lowest (α=0.0250) and highest (α=0.0297) mean inbreeding coefficients, respectively, among the ethnic groups in Afghanistan. The study shows that Afghanistan's populations, like other Islamic populations, have a high level of consanguinity.

Association between healthy life expectancy at birth and consanguineous marriages in 63 countries

In order to investigate the association between mean inbreeding coefficient (α) and healthy life expectancy at birth (HALE; years) the present ecological study on 63 countries was done. Statistical analysis showed that HALE negatively and positively correlated with log(10)α and log(10)GNI per capita, respectively (p<0.001). It should be noted that log(10)α and log(10)GNI per capita were significantly correlated with each other (p<0.001). After controlling for log(10)GNI per capita, significant negative correlations between log(10)α and HALE were observed. The countries were stratified according to their GNI per capita into low- and high-income countries. In countries with high income, after controlling for log(10)GNI per capita, the correlation between HALE at birth and log(10)α was significant (for males r=-0.399, df=32, p=0.001; for females r=-0.683, df=32, p<0.001). In high-income Asian and African countries, where consanguineous marriage is common, after controlling for log(10)GNI per capita, the correlation between HALE at birth and log(10)α was significant (for males r=-0.819, df=8, p=0.004; for females r=-0.936, df=8, p<0.001). It seems that consanguinity influences HALE independent of country income.

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.

PREVALENCE OF CONSANGUINEOUS MARRIAGES AMONG IRANIAN GEORGIANS

Consanguineous marriage – marriage between relatives – has received a great deal of attention as a potential risk factor for many adverse health outcomes. The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among Iranian Georgians living in Frydoonshahr (Isfahan province, central Iran). Data on consanguineous marriages were collected using a simple questionnaire. The total number of couples in this study was 646. Consanguineous marriage was classified by the degree of relationship between couples. First cousin marriages (14.2%) were the most common type of consanguineous marriages, followed by second cousin (7.0%), beyond second cousin (1.5%) and first cousin once removed (0.6%). The mean inbreeding coefficient (α) was calculated as 0.0104 for the population. The present study shows that the study population, as other Iranian populations, has a high level of consanguinity.

Developing and evaluating a culturally appropriate genetic service for consanguineous South Asian families

Blackburn with Darwen Primary Care Trust (PCT) provides services to a substantial Asian population in which the practice of consanguineous marriage is common and there is a high incidence of autosomal recessive disorders. The aim was to provide and evaluate a genetic service accessible to consanguineous families from the South Asian community who had a child affected by an autosomal recessive disorder. Information on genetic risk was provided along with the offer of genetic testing for members of the extended family to identify gene carriers and facilitate informed reproductive choices. An Urdu-speaking health visitor was employed to establish a community-based, hospital-linked genetic service in conjunction with local paediatric and regional genetic services offered to parents who had an affected child and 71 of their relatives. The service was evaluated using a specifically designed questionnaire. There was a high uptake of the service (95% of index parents and 92% of relatives to whom it was offered) and a high uptake of carrier testing (94% of relatives to whom it was offered). Eight requests for prenatal diagnosis were made during the course of the service development. Many individuals stated they would consider genetic risk when making future marriage and reproductive plans. Input from a health care worker from the same ethnic background who provided information in their own language was highly valued. Family orientated genetic services for ethnic groups practicing consanguinity can be acceptable and effective when provided in a culturally appropriate manner.

Consanguinity in Qatar: knowledge, attitude and practice in a population born between 1946 and 1991

From March 2007 to March 2008 a cross-sectional study was conducted in Qatar to estimate the prevalence of consanguinity among Qataris and to assess their knowledge of the risks and their attitudes towards the practice. A secondary objective was to test the acceptability of sixteen Likert-style questions within the Qatari population. Face-to-face interviews using a 70-item structured questionnaire were conducted by three native Arabic-speaking medical students with 362 Qatari employees. Where consanguinity existed between the employee's parents, a diagram of the consanguinal relationship (phylogram) was completed. The response rate was 93%. By phylogram, 22% of participants reported a cousin relationship between their parents (consanguinal relationship) and another 15% reported that their parents were from the same tribe (affinal relationship). With respect to their own marital decision, 68% of the respondents had been married at least once. By phylogram, 35% of these reported a consanguineous relationship (first marriage), 9% reported only an affinal relationship and 56% reported that they were not married to a blood relative. Results on the sixteen Likert-style attitude questions were stratified by consanguinity status of parents and of self. In the stratification by consanguinity status of parents the top five attitudes differed by group but there appeared to be more similarity between the consanguinal and only tribal groups. Attitudinal results were stratified by sex. Results showed that the males had a stronger belief in several of the attitudes than females with the exception of causation of genetic abnormalities and health problems. The phylogram was shown to collect more detailed and explicit data than hard-coding. With respect to knowledge, the results showed that knowledge was imperfect with high proportions of participants not knowing that consanguinity has been implicated in autosomal recessive diseases such as thalassaemia, inborn errors of metabolism, deafness, anomalies of the extremities and specific congenital heart defects. Additionally, a sizeable proportion of the participants did not know that a more distant cousin marriage (e.g. third cousin) theoretically could be a less genetically risky choice to potential offspring than a closer cousin marriage (half-first cousin). These results indicate that more effort needs to be made in developing public health strategies to improve the population's understanding of the cost-benefit analysis involved in contracting consanguineous marriages given the goal of healthy offspring.

EFFECT OF INBREEDING ON WEIGHT GAIN OF OFFSPRING FROM BIRTH TO 12 MONTHS AFTER BIRTH: A STUDY FROM IRAN

Consanguinity, the marriage between relatives, has been associated with adverse child health outcomes. The objective of the present study was to assess the effect of consanguinity on offspring weight gain from birth to 12 months after birth. Data were collected on 250 consecutive live-born singleton newborns referred to a local health centre in Shiraz (Fars province, southern Iran). Collected data covered socio-demographic characteristics (such as parental age at delivery and parental education), sex, birth order, weights from birth to 12 months after birth and consanguinity of marriages of parents. Considering the low prevalence of double first cousin, first cousin once removed, second cousin, and beyond second cousin marriages, only first cousin and unrelated marriages were included in the study. The study population consisted of a total of 207 newborns (57 offspring of first cousins, 150 offspring of unrelated marriages). Based on the results of repeated measurements analysis of variance, weight gain was associated with type of marriage (p=0.018), sex of offspring (p=0.001) and paternal education (p<0.001). There was no interaction between type of marriage and sex (p=0.831). Birth weight was not affected by type of marriage (p=0.46). There was significant interaction between inbreeding and time (p=0.034). Offspring of consanguineous marriages showed lower weight gain in comparison with those of unrelated marriages during 3–12 months after birth.

Consanguinity and reproductive health among Arabs

Consanguineous marriages have been practiced since the early existence of modern humans. Until now consanguinity is widely practiced in several global communities with variable rates depending on religion, culture, and geography. Arab populations have a long tradition of consanguinity due to socio-cultural factors. Many Arab countries display some of the highest rates of consanguineous marriages in the world, and specifically first cousin marriages which may reach 25-30% of all marriages. In some countries like Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. Research among Arabs and worldwide has indicated that consanguinity could have an effect on some reproductive health parameters such as postnatal mortality and rates of congenital malformations. The association of consanguinity with other reproductive health parameters, such as fertility and fetal wastage, is controversial. The main impact of consanguinity, however, is an increase in the rate of homozygotes for autosomal recessive genetic disorders. Worldwide, known dominant disorders are more numerous than known recessive disorders. However, data on genetic disorders in Arab populations as extracted from the Catalogue of Transmission Genetics in Arabs (CTGA) database indicate a relative abundance of recessive disorders in the region that is clearly associated with the practice of consanguinity.

Prevalence of consanguineous marriages in Syria

Consanguineous marriage is the union of individuals having at least one common ancestor. The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages in the Syrian Arab Republic. Data on consanguineous marriages were collected using a simple questionnaire. The total number of couples in this study was 67,958 (urban areas: 36,574 couples; rural areas: 31,384 couples) from the following provinces: Damascus, Hamah, Tartous, Latakia, Al Raqa, Homs, Edlep and Aleppo. In each province urban and rural areas were surveyed. Consanguineous marriage was classified by the degree of relationship between couples: double first cousins (F=1/8), first cousins (F=1/16), second cousins (F=1/64) and beyond second cousins (F<1/64). The coefficient of inbreeding (F) was calculated for each couple and the mean coefficient of inbreeding (alpha) estimated for the population of each province, stratified by rural and urban areas. The results showed that the overall frequency of consanguinity was 30.3% in urban and 39.8% in rural areas. Total rate of consanguinity was found to be 35.4%. The equivalent mean inbreeding coefficient (alpha) was 0.0203 and 0.0265 in urban and rural areas, respectively. The mean proportion of consanguineous marriages ranged from 67.5% in Al Raqa province to 22.1% in Latakia province. The alpha-value ranged from 0.0358 to 0.0127 in these two provinces, respectively. The western and north-western provinces (including Tartous, Lattakia and Edlep) recorded lower levels of inbreeding than the central, northern and southern provinces. The overall alpha-value was estimated to be about 0.0236 for the studied populations. First cousin marriages (with 20.9%) were the most common type of consanguineous marriages, followed by double first cousin (with 7.8%) and second cousin marriages (with 3.3%), and beyond second cousin was the least common type.

An association between the kinship and fertility of human couples

Previous studies have reported that related human couples tend to produce more children than unrelated couples but have been unable to determine whether this difference is biological or stems from socioeconomic variables. Our results, drawn from all known couples of the Icelandic population born between 1800 and 1965, show a significant positive association between kinship and fertility, with the greatest reproductive success observed for couples related at the level of third and fourth cousins. Owing to the relative socioeconomic homogeneity of Icelanders, and the observation of highly significant differences in the fertility of couples separated by very fine intervals of kinship, we conclude that this association is likely to have a biological basis.

Population stratification and genetic association studies in South Asia

Population stratification and its influence on genetic association studies is a controversial topic. Although it has been suggested that stratification is unlikely to bias the results of association studies conducted in developed countries, convincing contrary empirical evidence has been published. However, it is in populations where historical ethnic, religious and language barriers exist that community subdivisions will predictably exert greatest genetic effect, and influence the organization of association studies. In many of the populations of the Indian sub-continent, these basic population divisions are compounded by a strict tradition of intra-community marriage and by marriage between close biological relatives. Data on the very significant levels of genetic diversity that characterize the populations of India and Pakistan, with some 50,000-60,000 caste and non-caste communities in India, and average first cousin marriage rates of 40%-50% in Pakistan, are presented and discussed. Under these circumstances, failure to explicitly control for caste/biraderi membership and the presence of consanguinity could seriously jeopardize, and may totally invalidate, the results of association/case control studies and clinical trials.

Consanguinity and Associated Socio-Demographic Factors in Qatari Population

A multi-stage sampling design was used between January and May 2004 to explore the association between sociodemographic factors and consanguineous marriages in the Qatari population using a sample of 1800 Qatari females aged 15 years and above. Data on 1515 (85.8%) Qatari national families who gave their consent for the study were obtained. The socio-demographic factors considered were: husband's age, her own age, husband's and own educational levels, husband's occupationher own occupation, housing conditions, husband's parental kinship, her own parental kinship and kinship between the spouses. The rate of consanguineous marriages in the sample was found to be 54% with 95% estimated population confidence limits 52.4% to 55.6%. Consanguinity was more common for women with educated husbands (secondary or university / high) and the frequency of consanguineous marriage significantly increased when the husband's educational level was higher (p = 0.003). The results of stepwise multiple logistic regression analysis for the occurrence of consanguineous marriages showed that the wife's education, the husband's education and parents’ consanguinity status were the only significant associated variables.

The effect of consanguineous marriage on reading disability in the Arab community

The present study examined the effect of consanguineous marriage in the Arab community on reading disabilities of offspring. It examined whether the rate of reading disabilities was higher among offspring of first-cousin parents than offspring of unrelated parents; and whether reading-disabled children of first-cousin parents were more disabled in phonological awareness and phonological decoding than reading-disabled children of unrelated parents and normally reading younger children. These questions were investigated among 814 pupils of the 4th, 5th, and 6th grades, using word recognition and reading comprehension tests. Two experimental groups were chosen from this population. These were a reading-disabled group of 22 pupils who were children of first-cousin marriages and 21 pupils who were children of unrelated parents. A control group was also selected, consisting of 21 younger normally reading pupils at the same reading level. All the groups were tested on non-words, real words, phonological, orthographic and working memory measures. The results indicated that the rate of reading disabilities among children of first-cousin parents was higher than that of with children of second-cousin parents, distantly related parents, or unrelated parents. Further, no differences were found in phonological awareness and decoding between the two reading-disabled groups. Moreover, the results indicate a significant advantage of the younger normal readers over the reading-disabled children in the measures of phonological awareness, decoding, and orthographical knowledge that requires spelling. However, in reading common words and choosing words in context, the performance of the reading-disabled groups and the normally reading group were similar. It has been suggested that further research is needed to evaluate the role of intelligence, nevertheless our results provide new evidence for a genetic basis to reading disabilities.

Heterogeneity of breast cancer risk within the South Asian female population in England: a population-based case-control study of first-generation migrants

South Asian women in England have a lower breast cancer risk than their English-native counterparts, but less is known about variations in risk between distinct South Asian ethnic subgroups. We used the data from a population-based case-control study of first-generation South Asian migrants to assess risks by ethnic subgroup. In all, 240 breast cancer cases, identified through cancer registries, were individually matched on age and general practitioner to two controls. Information on the region of origin, religious and linguistic background, and on breast cancer risk factors was obtained from participants. Breast cancer odds varied significantly between the ethnic subgroups (P=0.008), with risk increasing in the following order: Bangladeshi Muslims (odds ratio (OR) 0.33, 95% confidence interval (CI): 0.10, 1.06), Punjabi Hindu (OR 0.59, 95% CI: 0.33, 1.27), Gujarati Hindu (1=reference group), Punjabi Sikh (OR 1.23, 95% CI: 0.72, 2.11) and Pakistani/Indian Muslims (OR 1.76, 95% CI: 1.10, 2.81). The statistically significant raised risk in Pakistani/Indian Muslims increased with adjustment for socioeconomic and reproductive risk factors (OR 2.12, 95% CI: 1.25, 3.58), but was attenuated, and no longer significant, with further adjustment for waist circumference and intake of nonstarch polysaccharides and fat (OR 1.49, 95% CI: 0.85, 2.63). These findings reveal differences in breast cancer risk between South Asian ethnic subgroups, which were not fully explained by reproductive differences, but were partly accounted for by diet and body size.

Congenital heart disease and associated malformations in children with cleft lip and palate in Pakistan

Children with cleft lip and palate often have other associated malformations. The reported incidence and types of associated malformations vary between different studies. There is a great paucity of literature on the subject from the region in general and none from Pakistan at all. The purpose of this study was to assess the frequency of associated malformations, particularly congenital heart disease, in children with cleft lip and palate presenting to the Aga Khan University (AKU) and Murshid Hospital (MH). From 1st October 1999 to 31st March 2002, all children with cleft lip and palate who presented to AKU and MH were prospectively enrolled in the study group. Socio-demographic characteristics and a number of other variables were documented. All children underwent a thorough clinical examination and an echocardiogram as part of the study protocol. 123 children formed the study group. Thirty-five (29%) of these children were found to have associated malformations. The most common of these was congenital heart disease, which accounted for 51% of all associated malformations. Thirty percent of cleft palate children had associated anomalies while 27% of cleft lip, with or without cleft palate, children had associated anomalies. There was a significant association between children born of a consanguineous marriage and the risk of associated malformations (p-value: 0.001). Consanguinity was present in 74% of children with associated anomalies as compared to 40% of children with no associated anomaly. Dysmorphic features and the presence of associated anomalies were also significantly associated (p-value: 0.009). Dysmorphic features were present in 46% of children with anomalies as compared to 21% of children with no associated anomaly. Fifty percent of children with associated anomalies had a low birth weight compared to 34% of children with no anomalies, but the difference was not statistically significant. The presence of consanguinity in a child with dysmorphic features should raise the suspicion of an associated anomaly. The likelihood of this being a cardiac defect is high and should be ruled out with a thorough clinical examination, supplemented with an echocardiogram in certain cases.

Contribution of BRCA1 and BRCA2 mutations to breast and ovarian cancer in Pakistan

The population of Pakistan has been reported to have the highest rate of breast cancer of any Asian population (excluding Jews in Israel) and one of the highest rates of ovarian cancer worldwide. To explore the contribution that genetic factors make to these high rates, we have conducted a case-control study of 341 case subjects with breast cancer, 120 case subjects with ovarian cancer, and 200 female control subjects from two major cities of Pakistan (Karachi and Lahore). The prevalence of BRCA1 or BRCA2 mutations among case subjects with breast cancer was 6.7% (95% confidence interval [CI] 4.1%-9.4%), and that among case subjects with ovarian cancer was 15.8% (95% CI 9.2%-22.4%). Mutations of the BRCA1 gene accounted for 84% of the mutations among case subjects with ovarian cancer and 65% of mutations among case subjects with breast cancer. The majority of detected mutations are unique to Pakistan. Five BRCA1 mutations (2080insA, 3889delAG, 4184del4, 4284delAG, and IVS14-1A-->G) and one BRCA2 mutation (3337C-->T) were found in multiple case subjects and represent candidate founder mutations. The penetrance of deleterious mutations in BRCA1 and BRCA2 is comparable to that of Western populations. The cumulative risk of cancer to age 85 years in female first-degree relatives of BRCA1-mutation-positive case subjects was 48% and was 37% for first-degree relatives of the BRCA2-mutation-positive case subjects. A higher proportion of case subjects with breast cancer than of control subjects were the progeny of first-cousin marriages (odds ratio [OR] 2.1; 95% CI 1.4-3.3; P=.001). The effects of consanguinity were significant for case subjects with early-onset breast cancer (age <40 years) (OR=2.7; 95% CI 1.5-4.9; P=.0008) and case subjects with ovarian cancer (OR=2.4; 95% CI 1.4-4.2; P=.002). These results suggest that recessively inherited genes may contribute to breast and ovarian cancer risk in Pakistan.

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.

Consanguinity and early mortality in the Muslim populations of India and Pakistan

Empirical information from studies conducted in Pakistan has indicated a high level of offspring mortality that can be attributed to parental consanguinity even when non-biological variables are controlled. However, with the exception of some small and geographically restricted studies, few comparable data are available on the influence of inbreeding in child survival among the Muslim population of India, which numbers between 100 and 120 million. The present study compares deaths during the first 5 years of life among the offspring of first cousin (F = 0.0625) and non-consanguineous unions (F = 0), using data collected in the 1992-1993 Indian National Family Health Survey (NFHS) and the 1990-1991 Pakistan Demographic and Health Survey (PDHS). The focus was on determinants of mortality in live-born children to age 5 years. In both countries, bivariate analyses indicated that mortality was significantly increased in the offspring of first cousin unions during the neonatal and post-neonatal, total infant, and under-5 year periods. The findings were confirmed by multivariate regression, which incorporated control for a range of biological and demographic factors.

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.