Title: Genes and Inherited Diseases
Headings: Genes and Inherited Diseases
Genes and Inherited Diseases
What is a Gene?
What is an Inherited Disease?
When Do Inherited Diseases Appear?
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Content: When Do Inherited Diseases Appear? Genetic disorders are typically inherited (passed down) in either a dominant or recessive manner. We each have two copies of every gene on our 22 numbered chromosomes. In addition, females have two copies of all the genes on the X chromosome, whereas males have one copy of the X chromosome genes and one copy of the Y chromosome genes. When a disorder is dominant, the disease can occur when there are DNA mistakes in only one of the two gene copies. This means that if a parent has the DNA change, there is a 50-50 chance that it will be passed on to each child. When a disorder is recessive, there must be mistakes in both copies of the gene for the disorder to occur. This means that both parents must carry at least one copy of the specific gene change in order to produce an affected child. If both parents have one changed copy, there is a 1 in 4, or 25% chance, that a child may inherit both changed copies at the same time, causing the disorder in the child. Parents who have only one changed gene copy usually do not display any symptoms of the disorder and may not even know they carry a gene change.