Several genes confirmed as responsible for schizophrenia and manic depressive illness

A group of researchers at the Centre de recherche Universite Laval Robert-Giffard, led by Dr. Michel Maziade, has just published what they are calling important scientific results on the identification of the genes involved in the causes of schizophrenia and manic depressive illness.

The team of researchers, whose work is funded by the Medical Research Council of Canada, Hydro-Quebec and the Fonds de la recherche en sante du Quebec, has confirmed that several genes are responsible for schizophrenia and manic depressive illness. Their results orient research into four specific regions of the chromosomes where there is a strong probability of finding these genes (chromosomes 11q, 3q, 18q and 6p).

This major step in research into schizophrenia and manic depressive illness, which began in 1990, has been reached after investigating about 20% of the genome in a sizeable sample of 650 members from large families in eastern Quebec that have been severely affected by these diseases over a number of generations.

Some of these results have been observed by other international groups as part of their systematic search of the genome. However, no other research group has been able to find such a set of strong genetic linkage signals in a comparable population, with only 20% of the genome examined. This achievement demonstrates the innovative nature of a number of methodological aspects of the study, as well as the genetic homogeneity of the eastern Quebec population.

These results add significantly to international knowledge and have made the following points even clearer: 1) certain of these genetic linkage signals are specific to each of these diseases, but the results suggest that some of the susceptibility genes are common to schizophrenia and manic depressive illness; 2) some of these genetic linkage trends have been observed in just one of the genealogical trees under study; 3) some results have been observed in most of the large families of the sample; 4) and some very large families show more than one linkage signal.

These results will influence international studies and contribute toward a better understanding of the complex nature of the genetic transmission of the two diseases.

So far, Dr. Maziade and his colleagues have published their research in a number of scientific journals, such as the American Journal of Medical Genetics, the British Journal of Psychiatry and the American Journal of Psychiatry. Other scientific journals will be reporting the results of the Quebec research in coming months.

The next steps in the study involve reviewing the genome and tripling the sample, in order to increase the statistical power to detect additional linkages to the defective genes. These studies will guarantee a better understanding of the causes of schizophrenia and manic depressive illness, and will ultimately lead to the development of early diagnostic tests and new curative treatments.

This research is expected to generate very important human, social and economic benefits. In Canada, each year, about 10% of the federal and provincial health budgets are spent on the direct costs of severe psychiatric illnesses, while 7% of hospital beds are occupied by people with schizophrenia.

In the United States, according to the National Foundation for Brain Research, the costs of psychiatric brain disorders are more than $136 billion, consisting of $62 billion in direct costs and $74 billion in indirect costs. Divided over a population of 238 million, this represents an annual cost of US $546, or approximately 5% of the average income of a worker.

For more Information (in French for the most part):

Also: For an interview with Dr. Maziade, M.D., FRCPC, Helene Bourque, Centre de recherche Universite Laval Robert-Giffard, (418) 663-5741, Internet:

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