Odds of Passing Schizophrenia on to Children

As an example, take two first order relatives - a brother and a sister. The brother has schizophrenia (though he is doing remarkably well). What are the chances that the offspring of the non-affected sister will develop schizophrenia? Are the odds affected by the number of children born to the sister? How does this compare to the general population.

Thanks in advance for your response.

[HFHS MD - RG]

The search for genetic risk factor has been examined through studies of twins, of families, and of children of schizophrenic parents who were adopted by others.

Twin studies have shown a concordance of 33-78% among identical (monozygotic) twins, but only 8-28% in fraternal (dizygotic ) twins.

Family studies reveal that first-degree relatives of schizophrenic person have aproximately a fivefold to 10-fold greater chance of developing schizophrenia than nonrelatives.

Children have about 35% chance of schizophrenia if bothparents have schizophrenia compared to 1% lifetime risk if neither parent has schizophrenia.

Although the results from family studies are thought to indicate genetic influences, environmental actors cannot be discounted.

There is no indication from studies that number of offspring increases or decreases the risk of schizophrenia.

Sincerely,

HFHS MD - RG