Consanguinity and mental retardation

Madhavan, Thuppal; Narayan, Jayanthi

doi:10.1111/j.1365-2788.1991.tb01042.x

Cited by 15 publications

(11 citation statements)

References 5 publications

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“…The study concluded that declines in IQ and the increase of mental retardation are consistent with rare recessive alleles associated with around 325 loci, whose likelihood of being transmitted into offspring increases with the relatedness of the parents. The study of Madhavan and Narayan (1991), which reported a similarly significantly high increase in the incidence of retardation, noted that within their sample the risks were highest in cases involving uncle-niece relationships.…”

Section: Deleterious Effects On Iq At Individual Data Levelsmentioning

confidence: 89%

Inbreeding depression and IQ in a study of 72 countries

Woodley

2009

Intelligence

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Section: Deleterious Effects On Iq At Individual Data Levelsmentioning

confidence: 89%

Inbreeding depression and IQ in a study of 72 countries

Woodley

2009

Intelligence

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“…In the offspring of first‐cousin matings, the prevalence of major congenital malformations (CM) is 2% to 2.5% higher than in children of unrelated parents; in Western countries, this more than doubles the CM risk ( and refs therein). Moreover, 3‐ to 5‐fold elevated intellectual disability (ID) risks have been reported for children whose parents are first cousins, but these estimates are based on few and mostly small studies with different designs, rendering direct comparisons difficult.…”

Section: Introductionmentioning

confidence: 99%

Effect of inbreeding on intellectual disability revisited by trio sequencing

Kahrizi

Hosseini

et al. 2018

Clinical Genetics

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In outbred Western populations, most individuals with intellectual disability (ID) are sporadic cases, dominant de novo mutations (DNM) are frequent, and autosomal recessive ID (ARID) is very rare. Because of the high rate of parental consanguinity, which raises the risk for ARID and other recessive disorders, the prevalence of ID is significantly higher in near‐ and middle‐east countries. Indeed, homozygosity mapping and sequencing in consanguineous families have already identified a plethora of ARID genes, but because of the design of these studies, DNMs could not be systematically assessed, and the proportion of cases that are potentially preventable by avoiding consanguineous marriages or through carrier testing is hitherto unknown. This prompted us to perform whole‐exome sequencing in 100 sporadic ID patients from Iran and their healthy consanguineous parents. In 61 patients, we identified apparently causative changes in known ID genes. Of these, 44 were homozygous recessive and 17 dominant DNMs. Assuming that the DNM rate is stable, these results suggest that parental consanguinity raises the ID risk about 3.6‐fold, and about 4.1 to 4.25‐fold for children of first‐cousin unions. These results do not rhyme with recent opinions that consanguinity‐related health risks are generally small and have been “overstated” in the past.

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“…Then, they can pass to their children in the form of ID. [ 14 16 17 ] The presence of other neurological disorders such as epilepsy, cerebral palsy, and severe mental illnesses in consanguineous relatives has also been found to be associated with ID in various studies. [ 14 18 19 ] A clinical study in South India has found that 30% of children with ID were born from parents who had a consanguineous marriage.…”

Section: Introductionmentioning

confidence: 99%

A Family Study of Consanguinity in Children with Intellectual Disabilities in Barwani, India

Lakhan

Bipeta

Yerramilli³

et al. 2017

Journal of Neurosciences in Rural Practice

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Background:Intellectual disability (ID) can be inherited in families through consanguineous marriage. The ID in an individual can be associated with the ID, epilepsy, and mental illness in their parents. Such connections can be seen more closely among consanguineous marriages in tribal and nontribal population in India.Objective:This study shows a few common patterns of the consanguineous relationship in the parents of children with ID in India.Materials and Methods:This is a case series research design. Extreme or deviant case sampling was applied. Data were collected in homes, camps, and clinical settings in the Barwani district of Madhya Pradesh, India. The patterns of consanguineous marriages and the relationship between children with ID and their relatives with ID, epilepsy, and mental illness were analyzed and reported with pedigree charts.Results:Multiple patterns of consanguineous marriages in tribal and nontribal populations were observed. ID was found to be associated in children with their relatives of the first, second, and third generations.Conclusion:ID may inherit in individuals from their relatives of the first, second, and third generations who have ID, epilepsy, or mental illness and married in the relationship. Appropriate knowledge, guidance, and counseling may be provided to potential couples before planning a consanguineous marriage.

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Consanguinity and mental retardation

Cited by 15 publications

References 5 publications

Inbreeding depression and IQ in a study of 72 countries

Inbreeding depression and IQ in a study of 72 countries

Effect of inbreeding on intellectual disability revisited by trio sequencing

A Family Study of Consanguinity in Children with Intellectual Disabilities in Barwani, India

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