Slide show: How genetic disorders are inherited
Illustration of autosomal dominant inheritance pattern
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In an autosomal dominant disorder, the mutated gene is located on one of the first 22 pairs of chromosomes (autosomes). You only need one copy of the mutated gene to be affected by this type of disorder.

A person with an autosomal dominant disorder — in this case, the father — has a 50 percent chance of passing the mutated copy of the gene (and having an affected child) and a 50 percent chance of passing the nonmutated copy of the gene (and having an unaffected child).

Huntington's disease and Marfan syndrome are two examples of autosomal dominant disorders. Mutations to BRCA1 and BRCA2 genes — which have been associated with breast cancer — also are transmitted in this pattern.

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