A disease is said to show incomplete penetrance when some individuals express the associated trait while others do not even though they carry the disease-causing gene. For instance, some people with a mutation in the BRCA1 or BRCA2 gene will develop cancer during their lifetime, other people will not.
Compare: complete penetrance
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... polydactyly is controlled by a dominant allele it is accompanied by incomplete penetrance hence not observed in majority of the population. The gene doesnot penetrate or ...
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