Study finds large proportion of intellectual disability is not genetically inherited

September 26, 2012

New research published Online First in The Lancet suggests that a high proportion of severe intellectual disability results from genetic causes that are not inherited. These findings are good news for parents, indicating a low risk of passing on the disorder to further children.

affects between 1% and 2% of children worldwide. Although a handful of genes that appear to cause some cases of intellectual disability have been identified, the of the disorder in most people remains unclear, especially those with non-syndromic types which have no obvious physical signs and cause up to 50% of intellectual disability worldwide.

Some evidence suggests that de novo (new) , that show up for the first time in affected children but are not found in their parents, might be a common cause of the disorder.

As a joint effort by the German Network led by André Reis from the Institute of Human Genetics, University of Erlangen-Nuremberg, Germany, the current study used a new technique known as exome sequencing to look for mutations that are not inherited but newly formed in 51 children with unexplained severe non-syndromic intellectual disability (an IQ <50) and their unaffected parents from nine centres across Germany and one center from Switzerland.

The researchers found that children with intellectual disability carried a significantly higher number of likely disease-causing mutations in their genome than those without the disorder. New mutations in both 11 known and six new were estimated to cause intellectual disability in up to 55% of the cases studied.

"Although believed to be relatively common in intellectual disability, these results suggest that only a small proportion of cases of sporadic intellectual disability are likely to be inherited in autosomal recessive fashion (affected children inherit one copy of the faulty from each parent)", explains Reis.

Writing in a linked Comment, Jozef Gecz and Eric Haan from the University of Adelaide in Australia point out, "Copy number variant profiling and whole-exome sequencing should resolve most (>60%) cases of severe intellectual disability. The remaining cases might be more complex, with contributions from multiple genes, environmental factors, or mutations in non-coding regions of the genome. Whole-genome sequencing technology has the potential to become the first-line diagnostic test for many disorders, and particularly intellectual disability."

Explore further: Intellectual disability is frequently caused by non-hereditary genetic problems

More information: www.thelancet.com/journals/lan … (12)61480-9/abstract

Related Stories

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 ...

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 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.

Most common form of inherited intellectual disability may be treatable

May 17, 2011
Advancements over the last 10 years in understanding intellectual disability (ID, formerly mental retardation), have led to the once-unimaginable possibility that ID may be treatable, a review of more than 100 studies on ...

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, ...

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.