Intellectual disability (ID) is a diagnosis given to persons who have life-long cognitive and adaptive impairments that commence in early life. ID affects about 1-3% of the population, thus nearly 1 million Canadians have an ID. The cause of ID is unknown in at least 40% of all cases. Recent reports have suggested that very tiny chromosome changes are the cause of many cases of ID. These tiny chromosome anomalies are usually not seen using routine microscopic analysis. However, recently developed microarray technology provides an opportunity to detect these very small changes.
Dr. Evica Rajcan-Separovic has used this technology to look for such abnormalities in 200 subjects with ID and have detected very small genetic changes in 16% cases. Some of the genetic abnormalities were seen in more than one individual. Her team plans to extend their array study to 400 more ID individuals in the next 6 years and to examine using molecular methods another 2000 subjects with ID to see if they can find additional individuals with the same abnormalities. By studying a larger number of individuals with the same chromosome change, they will be able to determine what physical features and medical issues are due to that genetic change.
Rajcan-Separovic's next step will be to develop Health Care Watches for each new condition identified. These will describe expected health issues, so that families and physicians can be better prepared to care for individuals with these new genetic syndromes. This approach will eliminate costly multiple testing and searching for answers, and should allow optimal care and health for persons with ID.