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.

CAMH Senior Scientist Dr. John Vincent and his team found a mutation in the gene NSUN2 among three sisters with , a finding to be published in the May issue of the .

The discovery was made after in a Pakistani family, in which three of seven siblings had intellectual disability as well as muscle weakness and walking difficulties, says Dr. Vincent, who heads the Molecular and Development Laboratory in the Campbell Family Mental Health Research Institute at CAMH.

Intellectual disability is a condition in which individuals have limitations in their mental abilities and in functioning in daily life. It affects one to three per cent of the population, and is often caused by .

Another study in the same journal, submitted together with the CAMH-led research, also identified NSUN2 gene mutations in Iranian and Kurdish families with intellectual disability. As with the Pakistani family, first cousin marriages in these families carrying the mutations increased the likelihood of intellectual disability among their children, and enabled researchers to focus on areas to map genes.

"The combined results from these two studies mean that NSUN2 is among the most common causes of intellectual disability resulting from recessive genes," says Dr. Vincent.

As a recessive disorder, a child must inherit one defective NSUN2 gene from each parent to develop intellectual disability. This gene, located on chromosome 5p, encodes a type of protein called an RNA .

At the cellular level, the researchers found that the mutated protein was prevented from reaching its target area within the nucleus of a cell. As a result, it was unable to perform its normal role in cell division and/or RNA methylation.

Collaborators from the Wellcome Trust Centre for Stem Cell Research in Cambridge, U.K., showed which type of brain cells were likely to be most affected by this mutation. They are called Purkinje cells, a type of neuron that responds to the neurotransmitter GABA. Purkinje cells also control motor coordination, which were affected in the Pakistani family.

"We speculate that the muscle effects may result from the accumulation of the NSUN2 protein outside its target area in the nucleus," says Dr. Vincent.

To date, Dr. Vincent's lab has identified five genes causing different forms of recessive intellectual disability.

Explore further: New gene for intellectual disability discovered

Related Stories

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 ...

New gene that causes intellectual disability discovered

May 12, 2011
A new study involving Canada's Centre for Addiction and Mental Health (CAMH) has found a gene connected with a type of intellectual disability called Joubert syndrome.

Intellectual disability is frequently caused by non-hereditary genetic problems

April 18, 2011
Mutations in a group of genes associated with brain activity frequently cause intellectual disability, according to a study led by scientists affiliated with the University of Montreal and the research centre at the Centre ...

Recommended for you

Scientists provide insight into genetic basis of neuropsychiatric disorders

July 21, 2017
A study by scientists at the Children's Medical Center Research Institute at UT Southwestern (CRI) is providing insight into the genetic basis of neuropsychiatric disorders. In this research, the first mouse model of a mutation ...

Scientists identify new way cells turn off genes

July 19, 2017
Cells have more than one trick up their sleeve for controlling certain genes that regulate fetal growth and development.

South Asian genomes could be boon for disease research, scientists say

July 18, 2017
The Indian subcontinent's massive population is nearing 1.5 billion according to recent accounts. But that population is far from monolithic; it's made up of nearly 5,000 well-defined sub-groups, making the region one of ...

Mutant yeast reveals details of the aberrant genomic machinery of children's high-grade gliomas

July 18, 2017
St. Jude Children's Research Hospital biologists have used engineered yeast cells to discover how a mutation that is frequently found in pediatric brain tumor high-grade glioma triggers a cascade of genomic malfunctions.

Late-breaking mutations may play an important role in autism

July 17, 2017
A study of nearly 6,000 families, combining three genetic sequencing technologies, finds that mutations that occur after conception play an important role in autism. A team led by investigators at Boston Children's Hospital ...

Newly discovered gene variants link innate immunity and Alzheimer's disease

July 17, 2017
Three new gene variants, found in a genome wide association study of Alzheimer's disease (AD), point to the brain's immune cells in the onset of the disorder. These genes encode three proteins that are found in microglia, ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

RobertKarlStonjek
not rated yet Apr 27, 2012
Purkinje cells are common and key neurons in the cerebellum, hence the coordination difficulties...

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.