Autosomal dominant
Alternative names:
genetics (autosomal dominant); inheritance (autosomal dominant)
Information:
Definition:
A single abnormal gene on one of the autosomal chromosomes (one of the first 22 "non-sex" chromosomes) from either parent can cause the disease. One of the parents will have the disease (since it is dominant) in this mode of inheritance and that person is called the CARRIER. Only one parent must be a carrier in order for the child to inherit the disease.
BACKGROUND:
The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome the abnormal gene resides on (autosomal or sex chromosome) and by whether the gene itself is dominant or recessive.
Autosomally inherited diseases are inherited through the non-sex chromosomes, pairs 1 through 22. Sex-linked diseases are inherited through one of the "sex chromosomes", the X chromosome (diseases are not inherited through the Y chromosome).
Dominant inheritance occurs when an abnormal gene from ONE parent is capable of causing disease even though the matching gene from the other parent is normal. The abnormal gene dominates the outcome of the gene pair.
Recessive inheritance occurs when BOTH matching genes must be abnormal to produce disease. If only one gene in the pair is abnormal the disease is not manifest or is only mildly manifest; however the disease can be passed on to the children.
STATISTICAL CHANCES OF INHERITING A TRAIT:
For an autosomal dominant disorder: If one parent is a carrier and the other normal there is a 50% chance a child will inherit the trait.
In other words, if it is assumed that 4 children are produced, one parent is carrier and exhibits disease, the STATISTICAL expectation is for:- 2 children normal
- 2 children with the disease
This does not mean that children WILL necessarily be affected; it does mean that EACH child has a 50:50 chance of inheriting the disorder.
RELATED TOPICS:
autosomal recessive
genetic counseling and prenatal diagnosis
sex-linked dominant
sex-linked recessive
For detailed information, see heredity and disease (genetics).
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