Researchers have identified a gene that causes a particular type of intellectual disability called 'Joubert syndrome'.
Joubert syndrome, which is a ciliopathy, affects brain functioning, resulting in intellectual deficits, movement and coordination problems and other symptoms such as kidney and eye problems.
Statistics reveal that the syndrome affects approximately 1 in 100,000 children, although this is likely to be a significant underestimate of the true prevalence.
Ciliopathies are caused by genetic defects to a part of the cell called the cilium. The cilium is crucial as it is involved with cell signalling pathways during cell development in different parts of the body.
The other ciliopathy gene identified in this study leads to a condition called nephronopthisis, which is also associated with kidney and eye problems.
"A defect in any aspect of this molecular pathway may have very similar effects at the clinical level," says Dr. Vincent, head of the Centre for Addiction and Mental Health's Molecular Neuropsychiatry and Development Laboratory.
Vincent's team found defects in the TCTN2 gene occurring in a family in Pakistan, in which four siblings had Joubert syndrome. According to them, the syndrome occurs when a child inherits a defective copy of the gene from each parent.
Vincent had previously discovered the CC2D2A gene, which is also associated with Joubert syndrome. Defects on this gene account for about 9 pc of cases of Joubert syndrome.
Till date, 10 genes have been connected with Joubert syndrome.
The study has been published in the current issue of Cell.