Consanguine marriage

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Consanguine marriage is marriage between individuals who are closely related. Though it may involve incest, it implies more than the sexual nature of incest. In a clinical sense, marriage between two family members who are second cousins or closer qualifies as consanguineous marriage. This is based on the gene copies their offspring may receive. [1] Though these unions are still prevalent in some communities, as seen across the Greater Middle East region, many other populations have seen a great decline in intra-family marriages. [2]

Contents

Prevalence and stigma

Global prevalence of consanguine marriage, illustrating a higher prevalence of cousin marriage in the Middle East in 2013 Global prevalence of consanguinity.svg
Global prevalence of consanguine marriage, illustrating a higher prevalence of cousin marriage in the Middle East in 2013

Globally, 8.5% of children have consanguineous parents, and 20% of the human population live in communities practicing endogamy. [3] [4] Theories on the developments of consanguineous marriage as a taboo can be supported as being both a social and a biological development. [2]

Social factors

From a social perspective, the observed inclination to practice consanguinity has been due to advantages to social and financial status. Upholding familial structure and assets, and ease of marital arrangements are valued among consanguineous marriages. [4] [5] Low age and a lack of awareness of the consequences of inbreeding are common in consanguineous marriages. [2]

Consanguineous marriage is present in every religion, and cannot be accredited to any one religious mandate. [4] Consanguinity is practiced regardless of religious influences and is a result of cultural, historical, regional, and socio-economic factors. [2] [6] A greater number of consanguineous marriages are observed in rural areas compared to urban areas within the same region. This is attributed to the tendency of individuals in rural areas to marry at younger ages, have a lower socio-economic status, and lesser education than those who live in urban areas. [7] [8] Parent's grade of job has also been credited as a factor. [5]

In cases of incest involving a child and adult, legislation usually considers it to be a form of child sexual abuse. [9] [10]

Epidemiological features

Cognitive abilities among inbred and non-inbred children in "families of five Muslim populations of [the] Jammu region." Cognitive abilities among inbred and non-inbred children.png
Cognitive abilities among inbred and non-inbred children in "families of five Muslim populations of [the] Jammu region."

Multiple studies have established consanguinity as a high cause for birth defects and abnormalities. A risk of autosomal recessive disorders increases in offspring coming from consanguineous marriages due to the increased likelihood of receiving recessive genes from cognate parents. [2] According to population based case-control studies, a higher risk of stillbirth is associated with consanguineous marriages. [12]

Inbreeding is associated with decreased cognitive abilities in children. [11]

Younger ages of marriage are commonly seen in consanguineous marriages, which may account for the increase in fertility seen in these unions. Chances of postnatal mortality are higher in offspring. The first year holds the highest chance of death due to the risk of autosomal recessive genes. This is also the cause of health complications as children born from consanguinity enter adulthood. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Incest</span> Sexual activity between immediate family members or people considered too closely related to marry

Incest is sex between close relatives, for example a brother, sister or a parent. This typically includes sexual activity between people in consanguinity, and sometimes those related by lineage. It is condemned and considered immoral in most societies, given that it can lead to an increased risk of genetic disorders in children in case of pregnancy from incestuous sex.

<span class="mw-page-title-main">Inbreeding</span> Reproduction by closely related organisms

Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely.

An incest taboo is any cultural rule or norm that prohibits sexual relations between certain members of the same family, mainly between individuals related by blood. All known human cultures have norms that exclude certain close relatives from those considered suitable or permissible sexual or marriage partners, making such relationships taboo. However, different norms exist among cultures as to which blood relations are permissible as sexual partners and which are not. Sexual relations between related persons which are subject to the taboo are called incestuous relationships.

Exogamy is the social norm of mating or marrying outside one's social group. The group defines the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. One form of exogamy is dual exogamy, in which two groups continually intermarry with each other.

Endogamy is the cultural practice of mating within a specific social group, religious denomination, caste, or ethnic group, rejecting any from outside of the group or belief structure as unsuitable for marriage or other close personal relationships. Its opposite, exogamy, describes the social norm of marriage outside of the group.

<span class="mw-page-title-main">Consanguinity</span> Property of being from the same kinship as another person

Consanguinity is the characteristic of having a kinship with a relative who is descended from a common ancestor.

The coefficient of relationship is a measure of the degree of consanguinity between two individuals. The term coefficient of relationship was defined by Sewall Wright in 1922, and was derived from his definition of the coefficient of inbreeding of 1921. The measure is most commonly used in genetics and genealogy. A coefficient of inbreeding can be calculated for an individual, and is typically one-half the coefficient of relationship between the parents.

<span class="mw-page-title-main">Pedigree collapse</span> Concept in genealogy

In genealogy, pedigree collapse describes how reproduction between two individuals who share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be. Robert C. Gunderson coined the term; synonyms include implex and the German Ahnenschwund.

A cousin is a relative that is the child of a parent's sibling; this is more specifically referred to as a first cousin.

Inbreeding depression is the reduced biological fitness that has the potential to result from inbreeding. The loss of genetic diversity that is seen due to inbreeding, results from small population size. Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression, though inbreeding and outbreeding depression can simultaneously occur.

Fumarase deficiency is an exceedingly rare autosomal recessive metabolic disorder in the Krebs cycle, characterized by a deficiency of the enzyme fumarate hydratase, which causes a buildup of fumaric acid in the urine and a deficiency of malate. Only 13 cases were known worldwide in 1990, after which a cluster of 20 cases was documented in a community in Arizona, US, that has practiced successive endogamy.

A cousin marriage is a marriage where the spouses are cousins. The practice was common in earlier times and continues to be common in some societies today, though in some jurisdictions such marriages are prohibited. Worldwide, more than 10% of marriages are between first or second cousins. Cousin marriage is an important topic in anthropology and alliance theory.

Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity.

In law, a prohibited degree of kinship refers to a degree of consanguinity, or sometimes affinity between persons that makes sex or marriage between them illegal.

Reproductive compensation was originally a theory to explain why recessive genetic disorders may persist in a population. It was proposed in 1967 as an explanation for the maintenance of Rh negative blood groups. Reproductive compensation refers to the tendency of parents, seeking a given family size, to replace offspring that are lost to genetic disorders. It may also refer to the effects of increased maternal or parental investment in caring for disadvantaged offspring, seeking to compensate for genetic disadvantage. It is a theory that suggests that behavioral as well as physiological factors may play a role in the level of recessive genetic disorders in a population.

<span class="mw-page-title-main">Cousin marriage in the Middle East</span> Consanguineous relationships in the Middle East

Cousin marriage is a form of consanguinity. While consanguinity is not unique to the Arab world, Arab countries have had "some of the highest rates of consanguineous marriages in the world". The bint 'amm marriage, or marriage with one's father's brother's daughter is especially common, especially in tribal and traditional Muslim communities, where men and women seldom meet potential spouses outside the extended family. Rates of cousin marriage in the Middle East have been found to vary from 29% in Egypt to nearly 58% in Saudi Arabia.

Genetic studies on Arabs refers to the analyses of the genetics of ethnic Arab people in the Middle East and North Africa. Arabs are genetically diverse as a result of their intermarriage and mixing with indigenous people of the pre-Islamic Middle East and North Africa following the Arab and Islamic expansion. Genetic ancestry components related to the Arabian Peninsula display an increasing frequency pattern from west to east over North Africa. A similar frequency pattern exist across northeastern Africa with decreasing genetic affinities to groups of the Arabian Peninsula along the Nile river valley across Sudan and the more they go south. This genetic cline of admixture is dated to the time of Arab migrations to the Maghreb and northeast Africa.

Inbreeding avoidance, or the inbreeding avoidance hypothesis, is a concept in evolutionary biology that refers to the prevention of the deleterious effects of inbreeding. Animals only rarely exhibit inbreeding avoidance. The inbreeding avoidance hypothesis posits that certain mechanisms develop within a species, or within a given population of a species, as a result of assortative mating and natural and sexual selection, in order to prevent breeding among related individuals. Although inbreeding may impose certain evolutionary costs, inbreeding avoidance, which limits the number of potential mates for a given individual, can inflict opportunity costs. Therefore, a balance exists between inbreeding and inbreeding avoidance. This balance determines whether inbreeding mechanisms develop and the specific nature of such mechanisms.

Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that are present in an individual due to parents transmitting identical haplotypes to their offspring.

Prevention of autosomal recessive disorders is focused on making it less likely that two carriers for the same hereditary disease will have children together.

References

  1. ↑ Hamamy, Hanan (November 22, 2011). "Consanguineous marriages". Journal of Community Genetics. 3 (3): 185–92. doi:10.1007/s12687-011-0072-y. PMC   3419292 . PMID   22109912.
  2. 1 2 3 4 5 Heidari F, Dastgiri S, Tajaddini N, et al. Prevalence and Risk Factors of Consanguineous Marriage. European Journal of General Medicine [serial online]. December 2014;11(4):248-255. Available from: Academic Search Complete, Ipswich, MA. Accessed October 4, 2016.
  3. ↑ Obeidat BG, Khader YS, Amarin ZO, Kassawneh M, AlOmari M (2010). "Consanguinity and adverse pregnancy outcomes: the north of Jordan experience". Matern Child Health J. 14 (2): 283–9.
  4. 1 2 3 Akrami SM, Montazeri V, Shomali SR, Heshmat R, Larijani B (2009). "Is there a significant trend in prevalence of consanguineous marriage in Tehran? A review of three generations". J Genet Couns. 18 (1): 82–6.
  5. 1 2 Shawky RM, El-Awady MY, Elsayed SM, Hamadan GE (2011). "Consanguineous matings among Egyptian population". Egypt J Med Human Genet. 12 (2): 157–63.
  6. ↑ Masood SN, Jamil N, Mumtaz SN, Masood MF, Muneer S (2011). "Congenital malformations in newborns of consanguineous and non-consanguineous parents". Pak J Med Sci. 27: 1–5.
  7. ↑ Tadmouri, GO; Nair, P; Obeid, T; et al. (2009). "Consanguinity and reproductive health among Arabs". Reproductive Health. 6: 17. doi: 10.1186/1742-4755-6-17 . PMC   2765422 . PMID   19811666.
  8. ↑ Sedehi M, Keshtkar A, Golalipour MJ. The Knowledge and the Attitude of Youth Couples On/Towards Consanguineous Marriages in the North of Iran. J Clin Diagnostic Res 2012;6(7):1233-6.
  9. ↑ Levesque, Roger J. R. (1999). Sexual Abuse of Children: A Human Rights Perspective. Indiana University Press. pp. 1,5–6,176–180.
  10. ↑ "United Nations Convention on the Rights of the Child". Office of the United Nations High Commissioner for Human Rights. 1989. Archived from the original on June 11, 2010.
  11. 1 2 Fareed, M; Afzal, M (2014). "Estimating the Inbreeding Depression on Cognitive Behavior: A Population Based Study of Child Cohort". PLOS ONE. 9 (10): e109585. Bibcode:2014PLoSO...9j9585F. doi: 10.1371/journal.pone.0109585 . PMC   4196914 . PMID   25313490.
  12. ↑ Maghsoudlou S, Cnattingius S, Bahmanyar S, et al. Consanguineous marriage, prepregnancy maternal characteristics and stillbirth risk: a population-based case-control study. Acta Obstetricia et Gynecologica Scandinavica [serial online]. October 2015;94(10):1095-1101. Available from: Academic Search Complete, Ipswich, MA. Accessed October 25, 2016.
  13. ↑ Bittles, Alan H. (1994). "The Role and Significance of Consanguinity as a Demographic Variable". Population and Development Review. 20 (3): 561–584. doi:10.2307/2137601. JSTOR   2137601.

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