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Effect of inbreeding on intellectual disability revisited by trio sequencing
Author(s) -
Kahrizi Kimia,
Hu Hao,
Hosseini Masoumeh,
Kalscheuer Vera M.,
Fattahi Zohreh,
Beheshtian Maryam,
Suckow Vanessa,
Mohseni Marzieh,
Lipkowitz Bettina,
Mehvari Sepideh,
Mehrjoo Zohreh,
Akhtarkhavari Tara,
Ghaderi Zhila,
Rahimi Maryam,
Arzhangi Sanaz,
Jamali Payman,
Falahat Chian Milad,
Nikuei Pooneh,
Sabbagh Kermani Farahnaz,
Sadeghinia Farnaz,
Jazayeri Roshanak,
Tonekaboni S. Hassan,
Khoshaeen Atefeh,
Habibi Haleh,
Pourfatemi Fatemeh,
Mojahedi Faezeh,
KhodaieArdakani MohammadReza,
Najafipour Reza,
Wienker Thomas F.,
Najmabadi Hossein,
Ropers HansHilger
Publication year - 2019
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/cge.13463
Subject(s) - consanguinity , inbreeding , exome sequencing , intellectual disability , genetics , biology , disease gene identification , medicine , gene , mutation , population , environmental health
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.