Has the long-predicted decline in consanguineous marriage in India occurred?

To an extent the question posed in the title of this paper can simply be answered in the affirmative. Based on the extensive data available from the National Family Health Survey-1 (NFHS-1) conducted in 1992-93 and NFHS-4 in 2015-16 there has been a significant overall decline of some 19% in the prevalence of consanguineous marriage in India. However, when examined at state level the picture is more complex, with large reductions in consanguinity in southern states where intra-familial marriage previously has been strongly favoured, whereas in some northern states in which close kin unions traditionally have been proscribed small increases were recorded. In a country such as India, comprising an estimated 18% of the current world population and with multiple ethnic, religious, geographical and social sub-divisions, apparently contrary findings of this nature are not unexpected - especially given the major shifts that are underway in family sizes, in education and employment, and with rapid urbanization. The changing health profile of the population also is an important factor, with non-communicable diseases now responsible for a majority of morbidity and premature mortality in adulthood. The degree to which future alterations in the prevalence and profile of consanguineous marriage occur, and at what rate, is difficult to predict - the more so given the markedly diverse cultural identities that remain extant across the Sub-Continent, and ongoing intra-community endogamy.

Beyond the panel: preconception screening in consanguineous couples using the TruSight One "clinical exome".

PURPOSE: To provide proof of concept by broadening preconception screening beyond targeted testing to inform reproductive risk in consanguineous couples. METHODS: Consanguineous couples were screened for autosomal recessive and X-linked disorders using the TruSight One panel of 4,813 genes associated with human disease. RESULTS: We recruited 22 couples, of whom 15 elected to have sequencing. We found four couples to be at risk of autosomal recessive disorders, including one with a child affected by Poretti-Boltshauser syndrome (a diagnosis not made prior to the study) and another previously known to carry a ß-globin variant. Two couples were found to carry variants unrelated to known family history. These variants were in the genes C5orf42 (associated with Joubert syndrome and orofaciodigital syndrome) and GYS2 (associated with glycogen synthase deficiency). One known variant was not detected-a single exon deletion in FAM20C. We would not expect to identify this variant with the methodology employed. Of the four variants identified, only the ß-globin variant would have been found using available commercial preconception screening panels. CONCLUSION: Preconception screening of consanguineous couples for recessive and X-linked disorders using genomic sequencing is practicable, and is likely to detect many more at-risk couples than any targeted panel could achieve. A couples-based approach greatly reduces the associated analysis and counselling burden.

User Acceptability of Whole Exome Reproductive Carrier Testing for Consanguineous Couples in Australia.

The study aimed to explore with consanguineous couples in Australia the acceptability and perceived utility of whole exome reproductive carrier screening for autosomal recessive and X-linked recessive conditions. Semi-structured interviews with 21 consanguineous couples were conducted prior to the offer of screening. Interviews were coded, and thematic analysis was informed by an inductive approach. Three major themes were identified: experiences and attitudes of Australian consanguineous couples, childhood genetic conditions and beliefs, and the perceived utility of genomic screening. All but one couple had previously sought genetic advice, and a large majority of couples were aware of childhood conditions within their family or community. Thirteen couples perceived consanguinity as increasing the risk of having affected children. Nine spoke of premarital screening programs routinely conducted in their countries of origin. All supported the concept and availability of genomic reproductive carrier screening. Hypothetically, if found to be carriers of a severe childhood disorder, 13 couples reported they would test a pregnancy, and 12 of whom would consider termination of pregnancy or pre-implantation genetic diagnosis. Four couples would not test a pregnancy and two were unsure. A majority of couples would communicate potential at-risk status to family members, although there were some caveats. Fourteen couples chose to have exome screening and reported that they would utilize the results with the goal of preventing childhood conditions. Of these couples, nine (64%) had an affected child but were aware that testing may reveal they were at risk for a child with a different condition and five (71%) without an affected child. While from diverse ethnic and backgrounds, all couples practiced a religion and all but one couple were recruited from the same clinical genetics unit, with a likely higher genetic literacy and bias towards accepting genetic testing. However, the choice made by all couples was reportedly made with consideration of their personal values, their current family situation, and exome testing issues, including fear of incidental findings and concerns about test reliability.

ESTIMATING THE HEALTH AND SOCIOECONOMIC EFFECTS OF COUSIN MARRIAGE IN SOUTH ASIA.

The effects of marriage between biological relatives on the incidence of childhood genetic illness and mortality are of major policy significance, as rates of consanguinity exceed 50% in various countries. Empirical research on this question is complicated by the fact that consanguinity is often correlated with poverty and other unobserved characteristics of households, which may have independent effects on mortality. This study has developed an instrumental variables empirical strategy to re-examine this question, based on the concept that the availability of unmarried cousins of the opposite gender at the time of marriage creates quasi-random variation in the propensity to marry consanguineously. Using primary data collected in Bangladesh in 2006-07 and Pakistan in 2009-10, the study found that previous estimates of the impact of consanguinity on child health were biased and falsely precise. The study also empirically investigated the social and economic causes of consanguinity (including marital quality) and concludes that marrying a cousin can have positive economic effects for one's natal family, by allowing deferral of dowry payments until after marriage.

Design of a framework for the deployment of collaborative independent rare disease-centric registries: Gaucher disease registry model.

Orphan drug clinical trials often are adversely affected by a lack of high quality treatment efficacy data that can be reliably compared across large patient cohorts derived from multiple governmental and country jurisdictions. It is critical that these patient data be captured with limited corporate involvement. For some time, there have been calls to develop collaborative, non-proprietary, patient-centric registries for post-market surveillance of aspects related to orphan drug efficacy. There is an urgent need for the development and sustainable deployment of these 'independent' registries that can capture comprehensive clinical, genetic and therapeutic information on patients with rare diseases. We therefore extended an open-source registry platform, the Rare Disease Registry Framework (RDRF) to establish an Independent Rare Disease Registry (IRDR). We engaged with an established rare disease community for Gaucher disease to determine system requirements, methods of data capture, consent, and reporting. A non-proprietary IRDR model is presented that can serve as autonomous data repository, but more importantly ensures that the relevant data can be made available to appropriate stakeholders in a secure, timely and efficient manner to improve clinical decision-making and the lives of those with a rare disease.

Rare disease registries: a call to action.

When registries collect accurate clinical data over time, they can act as fundamental support structures for patients and their families and powerful cost-effective instruments to support clinical trials and translational research to improve quality of care, quality of life and survival. Registries are critical for rare diseases (RD) with low prevalence and propensity for variation in treatment and outcomes. Rare Voices Australia is leading a call for action to the research and clinical community to prioritise RD data collection and develop an integrated RD Registry strategy for Australia. Financial, operational and governance challenges exist for establishing and maintaining RD registries. As a multidisciplinary team whose interests converge on RD, we highlight the need for the establishment of an Australian RD Registry Alliance. This 'umbrella' organisation will: (i) bring together existing RD registries across Australia; (ii) establish National RD Registry Standards to support interoperability and cohesion across registries; (iii) develop strategies to attract sustainable funding from government and other sources to maximise the utility of existing RD registries and support the development of new RD registries. The most important role for the Alliance would be to use the RD registries for translational research to address current knowledge gaps about RD and to improve the care for the over 1.4 million Australians estimated to live with RD.

ENDOGAMY, CONSANGUINITY AND THE HEALTH IMPLICATIONS OF CHANGING MARITAL CHOICES IN THE UK PAKISTANI COMMUNITY.

The biraderi (brotherhood) is a long-established, widely prevalent dimension of social stratification in Pakistani communities worldwide. Alongside consanguinity, it offers a route for cementing social solidarities and so has strong socio-biological significance. A detailed breakdown of biraderi affiliation among participants in an ongoing birth cohort study in the northern English city of Bradford is presented. There is historical resilience of intra-biraderi marriage, but with a secular decline in prevalence across all biraderi and considerable reductions in some. While a majority of marriages in all biraderi are consanguineous the prevalence varies, ranging from over 80% to under 60%. In consanguineous unions, first cousin marriages account for more than 50% in five of the fifteen biraderi and >40% in six others. Within-biraderi marriage and consanguinity enhance genetic stratification, thereby increasing rates of genomic homozygosity and the increased expression of recessive genetic disorders. The trends reported constitute putative signals of generational change in the marital choices in this community.

Consanguinity and pregnancy outcomes in a multi-ethnic, metropolitan European population.

OBJECTIVE: The aim of the present study was to assess the risk of major anomalies in the offspring of consanguineous couples, including data on the prenatal situation. METHODS: Over 20 years (1993-2012), 35,391 fetuses were examined by prenatal sonography. In 675 cases (1.9%), parents were consanguineous, with 307 couples (45.5%) related as first cousins, 368 couples (54.5%) beyond first cousins. Detailed information was retrieved on 31,710 (89.6%) fetuses, (consanguineous 568: 1.8%). RESULTS: Overall prevalence of major anomalies among fetuses with non-consanguineous parents was 2.9% (consanguineous, 10.9%; first cousins, 12.4%; beyond first cousins, 6.5%). Adjusting the overall numbers for cases having been referred because of a previous index case, the prevalences were 2.8% (non-consanguineous) and 6.1% (consanguineous) (first cousin, 8.5%; beyond first cousin, 3.9%). Further adjustment for differential rates of trisomic pregnancies indicated 2.0%/5.9% congenital anomalies (non-consanguineous/consanguineous groups), that is, a consanguinity-associated excess of 3.9%, 6.1% in first cousin progeny and 1.9% beyond first cousin. CONCLUSIONS: The prevalence of major fetal anomalies associated with consanguinity is higher than in evaluations based only on postnatal life. It is important that this information is made available in genetic counselling programmes, especially in multi-ethnic and multi-religious communities, to enable couples to make informed decisions.

Consanguineous marriage, reproductive behaviour and postnatal mortality in contemporary Iran.

OBJECTIVES: The aims of the study were to determine the prevalence, types and socio-economic correlates of consanguineous marriages in Iran, and to gauge the extent to which consanguinity influenced fertility, pregnancy outcomes and the expression of genetic disorders in the present-day population. METHODS: Data on the prevalence of consanguinity and birth outcomes in the first marriages of 5,515 women were abstracted from the 2005 Iran Low Fertility Study [Hosseini-Chavoshi et al: Fertility and Contraceptive Use Dynamics in Iran: Special Focus on Low Fertility Regions. Canberra, Australian National University, 2007]. The results of associated socio-economic variables were collated and assessed by Pearson's χ(2) analysis and logistic regression. RESULTS: Overall, 37.4% of the marriages were consanguineous (α = 0.0149), but with major differences between 4 representative populations. Consanguinity was higher among rural couples, older marriage cohorts, women marrying at a younger age, and women with lower levels of formal education. In general, consanguineous couples had higher mean numbers of pregnancies, live births and surviving children. CONCLUSIONS: Given declining family sizes, a rapid urbanization and increased educational and employment opportunities, it seems inevitable that consanguineous marriages will decline in prevalence in Iran, albeit more slowly in more traditional rural communities. Predictably, there will be a concomitant reduction in the incidence of recessive genetic disorders, but this is against a background transition from communicable to non-communicable diseases.

A community-based study of mucopolysaccharidosis type VI in Brazil: the influence of founder effect, endogamy and consanguinity.

Mucopolysaccharidosis type VI (MPS VI - Maroteaux-Lamy syndrome) is a globally rare lysosomal storage disease caused by a deficiency of arylsulfatase B. However, in Monte Santo, a poor and isolated rural region in Northeast Brazil with large family sizes and high rates of community endogamy and parental consanguinity (α = 0.00483), 9 living and 4 now deceased individuals in 11 kindreds have been diagnosed with MPS VI, all with the same p.H178L missense founder mutation. A further 33 deceased persons have been identified by family members as exhibiting the disease phenotype. Detailed pedigrees were constructed for the 13 genomically confirmed MPS VI patients, with blood samples collected from 236 unaffected family members to determine the prevalence of the p.H178L mutation. A total of 98 (20.8%) mutant alleles and 374 (79.2%) normal alleles were identified, with 41.5% of the individuals heterozygous for the p.H178L mutation and 58.5% homozygous for the normal allele. A significant number of other family members with a 50 or 25% chance of being heterozygous for the p.H178L mutation were unavailable for testing. The data indicate a compelling case for community-based neonatal screening in conjunction with further initiatives among MPS VI family members to promote genetic education and genetic counselling.

Consanguinity and the risk of congenital heart disease.

Consanguineous unions have been associated with an increased susceptibility to various forms of inherited disease. Although consanguinity is known to contribute to recessive diseases, the potential role of consanguinity in certain common birth defects is less clear, particularly since the disease pathophysiology may involve genetic and environmental/epigenetic factors. In this study, we ask whether consanguinity affects one of the most common birth defects, congenital heart disease, and identify areas for further research into these birth defects, since consanguinity may now impact health on a near-global basis. A systematic review of consanguinity in congenital heart disease was performed, focusing on non-syndromic disease, with the methodologies and results from studies of different ethnic populations compared. The risks for congenital heart disease have been assessed and summarized collectively and by individual lesion. The majority of studies support the view that consanguinity increases the prevalence of congenital heart disease, however, the study designs differed dramatically. Only a few (n = 3) population-based studies that controlled for potential sociodemographic confounding were identified, and data on individual cardiac lesions were limited by case numbers. Overall the results suggest that the risk for congenital heart disease is increased in consanguineous unions in the studied populations, principally at first-cousin level and closer, a factor that should be considered in empiric risk estimates in genetic counseling. However, for more precise risk estimates a better understanding of the underlying disease factors is needed.

ThalInd, a ß-thalassemia and hemoglobinopathies database for India: defining a model country-specific and disease-centric bioinformatics resource.

Web-based informatics resources for genetic disorders have evolved from genome-wide databases like OMIM and HGMD to Locus Specific databases (LSDBs) and National and Ethnic Mutation Databases (NEMDBs). However, with the increasing amenability of genetic disorders to diagnosis and better management, many previously underreported conditions are emerging as disorders of public health significance. In turn, the greater emphasis on noncommunicable disorders has generated a demand for comprehensive and relevant disease-based information from end-users, including clinicians, patients, genetic epidemiologists, health administrators and policymakers. To accommodate these demands, country-specific and disease-centric resources are required to complement the existing LSDBs and NEMDBs. Currently available preconfigured Web-based software applications can be customized for this purpose. The present article describes the formulation and construction of a Web-based informatics resource for ß-thalassemia and other hemoglobinopathies, initially for use in India, a multiethnic, multireligious country with a population approaching 1,200 million. The resource ThalInd (http://ccg.murdoch.edu.au/thalind) has been created using the LOVD system, an open source platform-independent database system. The system has been customized to incorporate and accommodate data pertinent to molecular genetics, population genetics, genotype-phenotype correlations, disease burden, and infrastructural assessment. Importantly, the resource also has been aligned with the administrative health system and demographic resources of the country.

Consanguineous marriages, pearls and perils: Geneva International Consanguinity Workshop Report.

Approximately 1.1 billion people currently live in countries where consanguineous marriages are customary, and among them one in every three marriages is between cousins. Opinions diverge between those warning of the possible health risks to offspring and others who highlight the social benefits of consanguineous marriages. A consanguinity study group of international experts and counselors met at the Geneva International Consanguinity Workshop from May 3, 2010, to May 7, 2010, to discuss the known and presumptive risks and benefits of close kin marriages and to identify important future areas for research on consanguinity. The group highlighted the importance of evidence-based counseling recommendations for consanguineous marriages and of undertaking both genomic and social research in defining the various influences and outcomes of consanguinity. Technological advances in rapid high-throughput genome sequencing and for the identification of copy number variants by comparative genomic hybridization offer a significant opportunity to identify genotype-phenotype correlations focusing on autozygosity, the hallmark of consanguinity. The ongoing strong preferential culture of close kin marriages in many societies, and among migrant communities in Western countries, merits an equivalently detailed assessment of the social and genetic benefits of consanguinity in future studies.

Haemoglobinopathies in India: estimates of blood requirements and treatment costs for the decade 2017-2026.

The Government of India is presently engaged in the implementation of a prevention and control programme for two major forms of haemoglobinopathies, thalassaemia major and sickle cell disease, with guidelines for their prevention and management formulated under the National Health Mission. Based on projections for the population up to the year 2026, the annual blood requirement for treatment will increase to 9.24 million units, together with an 86% increase in budgetary requirements which then would account for over 19% of the current National Health Budget. To avert a public health crisis there is an urgent need to fully implement the prevention programme for haemoglobinopathies.