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Inherited Disorders and Birth Defects

Mental illness inheritance risks

06/16/1999

Question:

Mental illness runs in my family. What are the risks, based on the latest research, that a child I give birth to would inherit schizophrenia or manic depression? Two brothers of mine are diagnosed as schizophrenics. One uncle was manic depressive. Also how does this risk compare to other risks of birth defects (for example Down`s Syndrome or deafness)? I am 40 years old, if that makes a difference in the stats.

Answer:

Schizophrenia is a brain disorder that affects how a person thinks, feels and acts. The person can have hallucinations, delusions (false ideas), inappropriate emotional responses, and disordered thinking. It affects about 1% of the general population.

Schizophrenia has a significant genetic component - but the genetics are complex. Researchers think that there may be a number of genes involved - thus a person may inherit a tendency to develop schizophrenia. Environmental events such as infections and stresses may also be involved and trigger the disorder. If a parent has schizophrenia his/her children would be at increased risk of also developing schizophrenia - about 10 times greater than the general population.

Manic depression, or bipolar disease, is another serious mental disorder that has both mania (excessively high moods) and depression (very low, helpless moods). The genetic component is similar to schizophrenia, in that it can run in families and that a person may inherit a `tendency` to develop the disorder. Here again, a first-degree relative would be at higher risk - thus if a parent has the disorder his/her children may be at increased risk to also have the disorder.

From your family history, it would be very appropriate for you to talk to a geneticist or genetic counselor to work out the specific risk figures for your children to have a mental illness. Because the genetics are very complex, it is impossible to be more specific using the internet. You can ask your doctor or contact the National Society of Genetic Counselors below to locate a genetics center near you. Also, the National Mental Health Association has an excellent website for additional information.

Finally, in comparison to other birth defects - the ones you asked about - the risk to have a baby with Down syndrome at age 40 is about 1 in 106. The risk of having a child with deafness depends on the family history and the type of deafness. There are many inherited forms of deafness. If there is no history of deafness, the risk should be low.

Related Resources:

National Mental Health Association
National Society of Genetic Counselors Resource Center

For more information:

Go to the Inherited Disorders and Birth Defects health topic, where you can:

Response by:

Judith A Westman, MD Judith A Westman, MD
Associate Professor, Clinical Internal Medicine, Pediatrics and Medical Biochemistry
College of Medicine
The Ohio State University