When a Parent Has an Abnormal Gene
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 (each parent has one abnormal gene)* | 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. | ||
See also Carrier Screening Carrier Screening Genetic screening is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder. Hereditary genetic disorders are disorders of chromosomes or... read more and Inheritance of Single-Gene Disorders Inheritance of Single-Gene Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more . | ||