"The previously identified gene MECP2 was only found in approximately 80 per cent of patients with Rett syndrome," said Dr. Berge Minassian, the study's principal investigator, a Sick Kids neurologist and scientist, and an assistant professor in the Department of Paediatrics at U of T. "Our discovery suggests that a defective alternate form of the MECP2 gene causes Rett syndrome."
The protein produced by the new alternate gene is different than the protein that was first associated with Rett syndrome in 1999. In the current work, this novel molecule was found to be disrupted in some Rett syndrome patients while the original form of the protein remained intact. The new protein is also the predominant form in the brain, strongly indicating that it is the disease-relevant protein.
"Our group's interest in Rett syndrome is relatively recent," said Dr. John Vincent, co-principal investigator of the study, head of the Molecular Neuropsychiatry & Development laboratory at CAMH, and assistant professor in the Department of Psychiatry at U of T. "Our fresh look at this problem was less affected by established dogma, and allowed us this new insight."
Rett syndrome is a genetic neurological disorder that occurs almost exclusively in girls, as the gene is found on the X chromosome. Babies with Rett syndrome appear to develop normally until 6 to 18 months of age. They then enter a period of regression, losing speech and other skills they had acquired. Most of the children develop seizures, repetitive hand movements, developmental delay, and motor-control problems, and they often have autistic tendencies. Rett syndrome is believed to affect 1 in 10,000 females.
"Since the Rett syndrome genetic tests are used not only to confirm a diagnosis of Rett syndrome, but also for 'negative inclusion' in other developmental disabilities such as cerebral palsy, forms of mental retardation and autism, we expect this new discovery to have great clinical utility," added Dr. Minassian.
Kathy Hunter, president and founder of the International Rett Syndrome Association (IRSA), applauded the new paper: "This is truly an exciting time for Rett syndrome research and is a major leap forward in our understanding of how MECP2 works in the nervous system. This critical discovery may be put into immediate practice. This finding will gladden the hearts of the thousands of families that must meet the challenges of Rett syndrome everyday. It brings us all hope that we are closer to finding answers that can ease our struggles."
This research was enabled through the assistance of clinical collaborators Dr. Carolyn Schanen at Nemours Biomedical Research, Alfred I. duPont Hospital for Children in Delaware, Dr. Patrick MacLeod at the University of British Columbia, and Dr. Michael Friez at Greenwood Genetic Center in South Carolina. This research was supported by the Canadian Institutes of Health Research - Neuromuscular Research Partnership, The Hospital for Sick Children Foundation, and a U of T Dean's Award to Dr. Vincent.
The Hospital for Sick Children, affiliated with the University of Toronto, is Canada's most research-intensive hospital and the largest centre dedicated to improving children's health in the country. Its mission is to provide the best in family-centred, compassionate care, to lead in scientific and clinical advancement, and to prepare the next generation of leaders in child health. For more information, please visit www.sickkids.ca.
The Centre for Addiction and Mental Health is the largest addiction and mental health organization in Canada. CAMH is a Pan American Health Organization and World Health Organization Collaborating Centre and a teaching hospital fully affiliated with the University of Toronto. For more information, visit www.camh.net.
Founded in 1827, the University of Toronto is Canada's leading teaching and research university with more than 60,000 students and 300,000 alumni worldwide. The university comprises 31 divisions, colleges and faculties on three campuses. This includes 14 professional faculties, numerous research centres and Canada's largest university library system - the fifth largest research library in North America. For the tenth consecutive year, U of T has taken the top spot among medical/doctoral universities in the annual Maclean's magazine university ranking.
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