Study links 26 novel genes to intellectual disability

April 11, 2017, Centre for Addiction and Mental Health
Credit: CC0 Public Domain

Researchers at the Centre for Addiction and Mental Health (CAMH) and Queen's University have identified 26 new genes linked to intellectual disability. Currently most patients with intellectual disability receive no molecular diagnosis, which significantly affects their health and shortens their lifespan.

The study, published online today in Molecular Psychiatry, has implications for the diagnosis and clinical care of those affected, and also adds to our growing knowledge of brain development and functioning. It may eventually lead to personalized treatments for affected individuals. Interestingly, some of the genes identified are thought to be connected with autism spectrum disorders.

"This is the largest study of its kind on to come out of North America," said Dr. John Vincent, team leader and Senior Scientist who heads the MiND (Molecular Neuropsychiatry and Development) Laboratory in the Campbell Family Mental Health Research Institute at CAMH. The study was jointly led with Prof. Muhammad Ayub of Queen's University.

More than one in 100 children worldwide are affected by intellectual disability, which is characterized by significant limitations in learning that also affect their day-to-day lives. Frequently, intellectual disability also accompanies symptoms of , and many genes have been found to be shared by the two illnesses.

The study involved 192 families from Pakistan and Iran with more than one affected family member. Intellectual disability is frequently caused by recessive genes, meaning that an affected child gets a defective copy of the gene from each parent.

The families in the study all had a history of marriage among relatives, which occurs quite commonly in communities in South Asia, the Middle East and Africa. Studying families with this background, and multiple affected individuals, can enable researchers to identify that would otherwise remain hidden.

The Canadian research team pinpointed mutations related to intellectual disability in half of these 192 families, in 72 different genes. The identification of 26 new genes adds to 11 new genes that the team had previously linked to intellectual disability.

Implications for diagnosis and care

One immediate implication of the study is to prevent future cases of intellectual disability, the researchers note. Unaffected family members and relatives could be genetically screened to see if they carry these mutations, and provided with counselling on the risks of "within family" marriages.

A broader goal is to develop diagnostic screening tools that are also relevant to populations in which "within " marriages are rare, such as Canada, USA, Japan, China and Europe. Ultimately, this information would be used to plan more personalized treatment.

While 26 genes may seem a substantial number, there are likely hundreds of genes that, when defective, may lead to intellectual disability. "The strategy we have used speeds up the process of identifying disease genes and of enabling diagnostic labs to deliver more accurate information for clinicians and families," says Dr. Vincent.

This strategy involves various genetic techniques, including microarray genotyping and whole exome sequencing, and studying families with a history of marriage among relatives.

"There's an opportunity now to further explore the functioning and biological pathways of these genes, and to help complete the picture of how the central nervous system works," says Dr. Vincent. "Knowing the involved is a big step forward, but understanding how they function is also crucial before we can start planning treatments or even cures."

Explore further: Two new genes linked to intellectual disability

More information: R Harripaul et al, Mapping autosomal recessive intellectual disability: combined microarray and exome sequencing identifies 26 novel candidate genes in 192 consanguineous families, Molecular Psychiatry (2017). DOI: 10.1038/MP.2017.60

Related Stories

Two new genes linked to intellectual disability

March 31, 2014
Researchers at the Centre for Addiction and Mental Health have discovered two new genes linked to intellectual disability, according to two research studies published concurrently this month in the journals Human Genetics ...

New form of intellectual disability discovered

April 27, 2012
Researchers at the Centre for Addiction and Mental Health (CAMH) led a study discovering a gene for a new form of intellectual disability, as well as how it likely affects cognitive development by disrupting neuron functioning.

New gene for intellectual disability discovered

July 15, 2011
A gene linked to intellectual disability was found in a study involving the Centre for Addiction and Mental Health (CAMH) – a discovery that was greatly accelerated by international collaboration and new genetic sequencing ...

Seven genes for X-linked intellectual disability

February 13, 2015
X-linked intellectual disability is a disorder that predominantly affects men and can have highly variable clinical manifestations. Scientists at the Max Planck Institute for Molecular Genetics in Berlin have found seven ...

Gene that causes intellectual disability when mutated finally identified

July 29, 2015
At least half of those with an intellectual disability across the world do not have a formal diagnosis. However, thanks to new DNA sequencing technology, along with the expertise and perseverance of University of Adelaide ...

Recommended for you

Suicide risk in abused teen girls linked to mother-daughter conflict

October 18, 2018
Teenage girls who were maltreated as children are more likely to entertain suicidal thoughts if the relationship with their mother is poor and the degree of conflict between the two of them high.

Study shows how bias can influence people estimating the ages of other people

October 17, 2018
A trio of researchers from the University of New South Wales and Western Sydney University has discovered some of the factors involved when people make errors in estimating the ages of other people. In their paper published ...

Infants are more likely to learn when with a peer

October 16, 2018
Infants are more likely to learn from on-screen instruction when paired with another infant as opposed to viewing the lesson alone, according to a new study.

Researchers use brain cells in a dish to study genetic origins of schizophrenia

October 16, 2018
A study in Biological Psychiatry has established a new analytical method for investigating the complex genetic origins of mental illnesses using brain cells that are grown in a dish from human embryonic stem cells. Researchers ...

Income and wealth affect the mental health of Australians, study shows

October 16, 2018
Australians who have higher incomes and greater wealth are more likely to experience better mental health throughout their lives, new research led by the Bankwest Curtin Economics Centre has found.

Study suggests biological basis for depression, anxiety, sleep disturbances in older adults

October 15, 2018
UC San Francisco researchers, in collaboration with the unique Brazilian Biobank for Aging Studies (BBAS) at the University of São Paulo, have shown that the earliest stages of the brain degeneration associated with Alzheimer's ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.