A gene linked to intellectual disability-a broad term describing individuals with limitations in mental abilities and in functioning in daily life due to genetic defects-has been discovered.
CAMH Senior Scientist Dr. John Vincent and colleagues identified defects on the gene, MAN1B1, among five families in which 12 children had intellectual disability.
The individuals affected had similar physical features, and all had delays in walking and speaking. Some learned to care for themselves, while others needed help bathing and dressing. In addition, some had epilepsy or problems with overeating.
All were found to have two copies of a defective MAN1B1 gene, one inherited from each parent. These were different types of mutations on the same gene - yet the outcome, intellectual disability, was the same in different families - confirming that this gene was the cause of the disorder.
"This mutation was seen in five families, which is one of the most seen so far for genes causing this form of recessive intellectual disability," said Dr. Vincent, who last year made a breakthrough by identifying the PTCHD1 gene responsible for autism.
To date, MAN1B1 is the eighth known gene connected with recessive intellectual disability, but there are likely many more involved. "We would like to screen children with intellectual disability in a western population," said Dr. Vincent.
The study will be published in the American Journal of Human Genetics.