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Genes determine physical and behavioral traits, with offspring inheriting one gene for each trait from each parent. Autosomal dominant genes can cause diseases or disorders, and mutations in these genes have a 50% chance of being passed on to offspring.
Most traits, both physical and behavioral, are passed on from parents to offspring, although some changes can arise due to a mutation or an error in the genetic code. The genes found within the cells of all organisms carry the information necessary for all traits to be expressed. During sexual reproduction, offspring inherit one gene for each trait from one parent and another copy from the other parent. Autosomal dominant genes are one way genes are inherited. The term autosomal dominant genesis is often used to describe the method of transmission of certain diseases and disorders.
Genes are the basis for all characteristics of an organism and exist in more than one form, called alleles. The different alleles for each gene code for different types of the same trait. For example, eye color is determined by the same gene, but differences in color are due to different alleles of this gene.
Not all alleles of a gene are expressed equally. Often, when a cell has different alleles for the same gene, one allele takes precedence over the other. The characteristic that is expressed is dominant over the one that is not. Continuing with the simplified eye color example, brown eye color is dominant over blue eye color. If a person has one allele for brown eyes and one allele for blue eyes, he will have brown eyes.
All genes exist on long strands of DNA called chromosomes. Sexually reproducing organisms have two types of chromosomes, autosomes and sex chromosomes. Sex chromosomes are the two chromosomes that determine the sex of the organism, while autosomes are all the other chromosomes. Autosomal dominant genes are inheritance of characteristics found on autosomes, not sex chromosomes.
Diseases and disorders can be caused by a mutation, or error, in a gene that runs through families. Autosomal dominant inheritance of a disease or disorder means that the abnormal gene is on one of the autosomes and the allele is dominant to the unchanged form. In these cases, only one copy of the abnormal gene is needed for the disease or disorder to be expressed in the offspring.
If a parent has a mutation in a dominant allele of a gene, there is a 50% chance that a child will also have the abnormal gene. Since the mutation is found on one of the autosomes, the sex of the offspring will not influence the outcome of the disease or disorder. A common example of a disorder caused by autosomal dominant genes is Huntington’s disease, or Huntington’s disease.
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