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<p style="text-align:justify;">Consanguineous marriage is made up of two words comprising of “Con” meaning same and sanguinous meaning blood relations. Thus, it is the relation between 2 individuals having same blood relations and a common ancestor. As per clinical genetics, a consanguineous marriage is defined as a union between two individuals who are related as second cousins or closer, with the inbreeding coefficient (F) equal or higher than 0.0156 where (F) represents a measure of the proportion of loci at which the offspring of a consanguineous union is expected to inherit identical gene copies from both parents.<ref name="ref14">Hamamy, Hanan. “Consanguineous marriages: Preconception consultation in primary health care settings.” Journal of community genetics vol. 3,3 (2012): 185-92. doi:10.1007/s12687-011-0072-y</ref> As per WHO statistics, unions contracted between persons biologically related as second cousins or closer are categorized as consanguineous, having one or more ancestors in common no more remote than a great-grandparent (consag.net; WHO document 1997, EUROCAT).<ref name="ref15">Jain S. Consanguinity and inherited epilepsies. Neurology Asia 2011; 16 (Supplement 1) : 11 – 12</ref> Consanguineous marriages are culturally and socially favoured in populations of North Africa, West Asia and South India, and constitute 20–50% of all marriages, with first cousins unions accounting for almost one-third of all marriages. These are very uncommon in countries like the USA and the United Kingdom but favoured in Middle East , Saudi Arabian, Africa and Pakistan.<ref name="ref16">Bittles A. Consanguinity and its relevance to clinical genetics. Clin Genet. 2001;60:89–98. doi: 10.1034/j.1399-0004.2001.600201.x. [PubMed] [CrossRef] [Google Scholar]</ref> Consanguinity is still a common aspect amongst Indian communities where about 30-40% of Muslims in northern India, a few communities in southern India, and parts of Maharashtra witness consanguineous marriages.<ref name="ref17">Kumar  D.  Epidemiology  of  Genetic  Diseases,  Book  Genetic Disorders of the Indian Subcontinent. Ch. 4. Dordrecht ; Boston: Kluwer Academic Publishers 2004; p. 81. (2) (PDF) Concept of genetic disorders in Ayurveda and their prevention. Available from: https://www.researchgate.net/publication/368678602_Concept_of_genetic_disorders_in_Ayurveda_and_their_prevention [accessed Feb 06 2024].</ref> Research has proved that a high rate of consanguineous marriages within the tribe and community can result in the transmission of a recessive gene and an increase in autosomal recessive disorders like mental retardation, dysmorphisms, congenital anomalies etc.<ref name="ref18">Hussain R, Bittles AH, Sullivan S.  Consanguinity and early mortality in the Muslim populations of India and Pakistan. Am J Hum Biol 2001;13:777 87. (2) (PDF).</ref> <br/>Darwin states that the consequence of close inbreeding or interbreeding carried on for a long time may lead to loss of size, constitutional vigor, and fertility, sometimes accompanied by malformations.<ref name="ref19">Adavoudi, Roya, and Małgorzata Pilot. “Consequences of Hybridization in Mammals: A Systematic Review.” Genes vol. 13,1 50. 24 Dec. 2021, doi:10.3390/genes13010050</ref> This leads to hybridization and widening of the genetic pool leading to gene diversification. <br/>Inbreeding is the result of the absence of heterozygosity leading to prevalent faulty genes. The genetic material shared by first cousins is four times higher than that shared by second cousins while the DNA of half-fourth cousin shows no evidence of gene sharing. Thus, consanguinity is not restricted to unions between individuals biologically related to a very lesser degree.<ref name="ref20">Meyer BF. Strategies for the prevention of hereditary diseases in a highly consanguineous population. Ann Hum Biol. 2005;32:174–179. doi: 10.1080/03014460500075217.</ref> Other reasons may include the young age of females during puberty, pregnancy at a very young age, low socioeconomic conditions, lack of awareness, and accessibility to healthcare.<ref name="ref21">Bhinder, Munir Ahmad et al. “Consanguinity: A blessing or menace at population level?.” Annals of human genetics vol. 83,4 (2019): 214-219. doi:10.1111/ahg.12308</ref> <br/>It is evident that robust research is available concerning the concept of consanguineous relations across the globe. Many prevalence studies , Geno-toxicity studies, systematic reviews have been carried out in this domain dealing with the health implications of marriages within individuals of same genetic lineage.<ref name="ref22">Cem Mete, Laurent Bossavie, John Giles & Harold Alderman (2020) Is consanguinity an impediment to child development?, Population Studies, 74:2, 139-159, DOI: 10.1080/00324728.2019.1699942</ref> Research suggests early postnatal mortality is higher in progeny of consanguineous marriages due to the expression of deleterious recessive genes. Thus, if the offspring receives the recessive gene from both parents it is most likely to suffer from that particular genetic disorder. The prenatal morbidity (stillbirths) and mortality, recurrent fetal abortions coupled with stillbirths are more common in consanguineous marriages than those in nonconsanguineous ones.<ref name="ref23">Bittles AH, Black ML. The impact of consanguinity on neonatal and infant health. Early Human Development. 2010 Nov 1;86(11):737–41.</ref> Similarly, genetic disorders like neural tube defects, congenital heart defects, impaired hearing, X-linked disorders like osteogenesis imperfecta, sickle cell anaemia, impaired immune function, inborn errors of metabolism etc. are also common in such conditions.<ref name="ref24">Centerwall WR,  Centerwall  SA.  Consanguinity and congenital anomalies in  South  India:  A  pilot  study.  Indian  J  Med  Res 1966;54:1160 7</ref> The consanguineous marriages were common previously to keep the family relations, and cultural and linguistic characteristics of the clan intact and to assure the distribution of wealth within the family to avoid property-related issues. This concept is thus similar to the concept of exogamy where marriages or relations outside of one’s social circle have been facilitated since the Neolithic age.<ref name="ref25">Knipper C, Mittnik A, Massy K, Kociumaka C, Kucukkalipci I, Maus M, et al. Female exogamy and gene pool diversification at the transition from the Final Neolithic to the Early Bronze Age in central Europe. Proceedings of the National Academy of Sciences. 2017 Sep 19;114(38):10083–8.</ref> The exogamy can be in the form of cultural, linguistic, or dual (patrilineal or matrilineal). The latest statistics (static and dynamic), and latest research articles regarding consanguineous relations are available on the website https://www.consang.net/.<ref name="ref26">Data, References [Internet]. [cited 2024 Feb 7]. Available from: https://www.consang.net/References/</ref></p>

<p style="text-align:justify;">Consanguineous marriage is made up of two words comprising of “Con” meaning same and sanguinous meaning blood relations. Thus, it is the relation between 2 individuals having same blood relations and a common ancestor. As per clinical genetics, a consanguineous marriage is defined as a union between two individuals who are related as second cousins or closer, with the inbreeding coefficient (F) equal or higher than 0.0156 where (F) represents a measure of the proportion of loci at which the offspring of a consanguineous union is expected to inherit identical gene copies from both parents.<ref name="ref14">Hamamy, Hanan. “Consanguineous marriages: Preconception consultation in primary health care settings.” Journal of community genetics vol. 3,3 (2012): 185-92. doi:10.1007/s12687-011-0072-y</ref> As per WHO statistics, unions contracted between persons biologically related as second cousins or closer are categorized as consanguineous, having one or more ancestors in common no more remote than a great-grandparent (consag.net; WHO document 1997, EUROCAT).<ref name="ref15">Jain S. Consanguinity and inherited epilepsies. Neurology Asia 2011; 16 (Supplement 1) : 11 – 12</ref> Consanguineous marriages are culturally and socially favoured in populations of North Africa, West Asia and South India, and constitute 20–50% of all marriages, with first cousins unions accounting for almost one-third of all marriages. These are very uncommon in countries like the USA and the United Kingdom but favoured in Middle East , Saudi Arabian, Africa and Pakistan.<ref name="ref16">Bittles A. Consanguinity and its relevance to clinical genetics. Clin Genet. 2001;60:89–98. doi: 10.1034/j.1399-0004.2001.600201.x. [PubMed] [CrossRef] [Google Scholar]</ref> Consanguinity is still a common aspect amongst Indian communities where about 30-40% of Muslims in northern India, a few communities in southern India, and parts of Maharashtra witness consanguineous marriages.<ref name="ref17">Kumar  D.  Epidemiology  of  Genetic  Diseases,  Book  Genetic Disorders of the Indian Subcontinent. Ch. 4. Dordrecht ; Boston: Kluwer Academic Publishers 2004; p. 81. (2) (PDF) Concept of genetic disorders in Ayurveda and their prevention. Available from: https://www.researchgate.net/publication/368678602_Concept_of_genetic_disorders_in_Ayurveda_and_their_prevention [accessed Feb 06 2024].</ref> Research has proved that a high rate of consanguineous marriages within the tribe and community can result in the transmission of a recessive gene and an increase in autosomal recessive disorders like mental retardation, dysmorphisms, congenital anomalies etc.<ref name="ref18">Hussain R, Bittles AH, Sullivan S.  Consanguinity and early mortality in the Muslim populations of India and Pakistan. Am J Hum Biol 2001;13:777 87. (2) (PDF).</ref> <br/>Darwin states that the consequence of close inbreeding or interbreeding carried on for a long time may lead to loss of size, constitutional vigor, and fertility, sometimes accompanied by malformations.<ref name="ref19">Adavoudi, Roya, and Małgorzata Pilot. “Consequences of Hybridization in Mammals: A Systematic Review.” Genes vol. 13,1 50. 24 Dec. 2021, doi:10.3390/genes13010050</ref> This leads to hybridization and widening of the genetic pool leading to gene diversification. <br/>Inbreeding is the result of the absence of heterozygosity leading to prevalent faulty genes. The genetic material shared by first cousins is four times higher than that shared by second cousins while the DNA of half-fourth cousin shows no evidence of gene sharing. Thus, consanguinity is not restricted to unions between individuals biologically related to a very lesser degree.<ref name="ref20">Meyer BF. Strategies for the prevention of hereditary diseases in a highly consanguineous population. Ann Hum Biol. 2005;32:174–179. doi: 10.1080/03014460500075217.</ref> Other reasons may include the young age of females during puberty, pregnancy at a very young age, low socioeconomic conditions, lack of awareness, and accessibility to healthcare.<ref name="ref21">Bhinder, Munir Ahmad et al. “Consanguinity: A blessing or menace at population level?.” Annals of human genetics vol. 83,4 (2019): 214-219. doi:10.1111/ahg.12308</ref> <br/>It is evident that robust research is available concerning the concept of consanguineous relations across the globe. Many prevalence studies , Geno-toxicity studies, systematic reviews have been carried out in this domain dealing with the health implications of marriages within individuals of same genetic lineage.<ref name="ref22">Cem Mete, Laurent Bossavie, John Giles & Harold Alderman (2020) Is consanguinity an impediment to child development?, Population Studies, 74:2, 139-159, DOI: 10.1080/00324728.2019.1699942</ref> Research suggests early postnatal mortality is higher in progeny of consanguineous marriages due to the expression of deleterious recessive genes. Thus, if the offspring receives the recessive gene from both parents it is most likely to suffer from that particular genetic disorder. The prenatal morbidity (stillbirths) and mortality, recurrent fetal abortions coupled with stillbirths are more common in consanguineous marriages than those in nonconsanguineous ones.<ref name="ref23">Bittles AH, Black ML. The impact of consanguinity on neonatal and infant health. Early Human Development. 2010 Nov 1;86(11):737–41.</ref> Similarly, genetic disorders like neural tube defects, congenital heart defects, impaired hearing, X-linked disorders like osteogenesis imperfecta, sickle cell anaemia, impaired immune function, inborn errors of metabolism etc. are also common in such conditions.<ref name="ref24">Centerwall WR,  Centerwall  SA.  Consanguinity and congenital anomalies in  South  India:  A  pilot  study.  Indian  J  Med  Res 1966;54:1160 7</ref> The consanguineous marriages were common previously to keep the family relations, and cultural and linguistic characteristics of the clan intact and to assure the distribution of wealth within the family to avoid property-related issues. This concept is thus similar to the concept of exogamy where marriages or relations outside of one’s social circle have been facilitated since the Neolithic age.<ref name="ref25">Knipper C, Mittnik A, Massy K, Kociumaka C, Kucukkalipci I, Maus M, et al. Female exogamy and gene pool diversification at the transition from the Final Neolithic to the Early Bronze Age in central Europe. Proceedings of the National Academy of Sciences. 2017 Sep 19;114(38):10083–8.</ref> The exogamy can be in the form of cultural, linguistic, or dual (patrilineal or matrilineal). The latest statistics (static and dynamic), and latest research articles regarding consanguineous relations are available on the website https://www.consang.net/.<ref name="ref26">Data, References [Internet]. [cited 2024 Feb 7]. Available from: https://www.consang.net/References/</ref></p>

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