When a Parent Has an Abnormal Gene
Inheritance Pattern |
Chance of Inheriting the Disorder |
Chance of Being a Carrier* |
|
Autosomal dominant |
50% for sons and daughters |
0% |
|
Autosomal recessive |
25% for sons and daughters if both parents are carriers* |
67% for children with no symptoms of the disorder if both parents are carriers 50% if only one parent has the gene |
|
X-linked dominant |
50% when the mother has the gene, usually only in daughters because the abnormal gene is often lethal in sons |
0% |
|
X-linked recessive |
50% for sons when the mother has the gene |
50% for daughters when the mother has the gene 100% for daughters when the father has the gene |
|
* Carriers have only one abnormal gene and usually have no symptoms of the disorder that the gene causes. |
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See also Carrier Screening and Inheritance of Single-Gene Disorders. |
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