" Our lives begin to end when we remain silent about things that matter "
... Dr Martin Luther King

M ental I llness Concerns All carers

genetics and inheritance

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Basic genetics... and/or ... with pictures

Relationship to an individual with schizophrenia Recurrence Risk (%) *

General population no relatives with Schizophrenia 1%

Parents with one child a sufferer, effect on subsequent child 1- 6 %

brothers and sisters 7- 14 %

offspring where one parent has schizophrenia 6- 16 %

Offspring of two parents who both have the illness 35 - 46 %

Second Degree Relative (e.g. Aunt /uncle) 2-8 %

Third Degree Relative (e.g. First cousin) 1-6 %

individuals whose schizophrenic symptoms develop earlier and are more severe may have more genes for schizophrenia, which would increase the risk to their relatives. Data on recurrence risks vary depending on the study, as well as many other factors. Therefore the above table gives only very general figures for the chance of an individual developing schizophrenia

The chance of an individual developing schizophrenia also decreases as they become older and remain symptom free. This is because people normally show symptoms of schizophrenia in their early 20s, if they are male, or late 20s, if they are female. For example, a person over 55 who is symptom free has basically no chance of developing schizophrenia, while a person over 40 has a much-reduced risk (26). Additionally, recurrence risks can be complicated by the presence of other related mental illnesses in the family such as schizoaffective disorder.

why does schizophrenia not 'die out'. Sufferers marry and conceive less than the general population.
But mutations add to the inheritance pool. Especially paternal genes where the father is over forty - sperm is being continually made - unlike ovaries which don't add from the beginning - and late paternal age sperm are more likely to carry mutations.

Dr. E. Fuller Torry (not a genetic counselor, but a well-known schizophrenia researcher and advocate, who has family experience ) has noted in his book "Surviving Schizophrenia " the following regarding genetic inheritance of schizophrenia,
"A majority of individuals who develop schizophrenia -- 63 percent -- do not have any family history of schizophrenia in first-degree (parents and siblings) or second-degree (grandparents, aunts, and uncles) relatives". Dr. Torrey also notes, however, that "the more relatives you have with schizophrenia, the higher your risk is of developing it.
From a practical point of view this means that if your sister is your only close relative with schizophrenia, your own risk is very low.
If, on the other hand, your uncle and sister both have schizophrenia, then your risk is higher.
And if you are unfortunate enough to come from one of the relatively rare families that are heavily loaded with the disorder
(e.g., mother, aunt, grandfather, and two siblings affected), then your own risk is substantially higher
and you should give serious consideration to the question of having children."

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Relationship to an individual with schizophrenia	Recurrence Risk (%) *
General population no relatives with Schizophrenia	1%
Parents with one child a sufferer, effect on subsequent child	1- 6 %
brothers and sisters	7- 14 %
offspring where one parent has schizophrenia	6- 16 %
Offspring of two parents who both have the illness	35 - 46 %
Second Degree Relative (e.g. Aunt /uncle)	2-8 %
Third Degree Relative (e.g. First cousin)	1-6 %
individuals whose schizophrenic symptoms develop earlier and are more severe may have more genes for schizophrenia, which would increase the risk to their relatives. Data on recurrence risks vary depending on the study, as well as many other factors. Therefore the above table gives only very general figures for the chance of an individual developing schizophrenia
The chance of an individual developing schizophrenia also decreases as they become older and remain symptom free. This is because people normally show symptoms of schizophrenia in their early 20s, if they are male, or late 20s, if they are female. For example, a person over 55 who is symptom free has basically no chance of developing schizophrenia, while a person over 40 has a much-reduced risk (26). Additionally, recurrence risks can be complicated by the presence of other related mental illnesses in the family such as schizoaffective disorder.
why does schizophrenia not 'die out'. Sufferers marry and conceive less than the general population. But mutations add to the inheritance pool. Especially paternal genes where the father is over forty - sperm is being continually made - unlike ovaries which don't add from the beginning - and late paternal age sperm are more likely to carry mutations.
Dr. E. Fuller Torry (not a genetic counselor, but a well-known schizophrenia researcher and advocate, who has family experience ) has noted in his book "Surviving Schizophrenia " the following regarding genetic inheritance of schizophrenia, "A majority of individuals who develop schizophrenia -- 63 percent -- do not have any family history of schizophrenia in first-degree (parents and siblings) or second-degree (grandparents, aunts, and uncles) relatives". Dr. Torrey also notes, however, that "the more relatives you have with schizophrenia, the higher your risk is of developing it. From a practical point of view this means that if your sister is your only close relative with schizophrenia, your own risk is very low. If, on the other hand, your uncle and sister both have schizophrenia, then your risk is higher. And if you are unfortunate enough to come from one of the relatively rare families that are heavily loaded with the disorder (e.g., mother, aunt, grandfather, and two siblings affected), then your own risk is substantially higher and you should give serious consideration to the question of having children."