Mutant genes that affect several organ systems and bodily functions frequently show variable expressivity. A phenomenon referred to as phenotypic variation. The most striking example of phenotypic variability is manifest in an autosomal dominant condition characterized by the appearance of café au lait spots on the skin and cutaneous and subcutaneous neurofibromas. These symptoms are associated with which of the following?

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Von Recklinghausen disease, also known as type I neurofibromatosis, is characterized by café au lait spots and neurofibromas, and it shows variable expressivity. This woman's history of chronic hepatitis B infection and cirrhosis greatly increase her risk for hepatocellular carcinoma. This diagnosis is confirmed by the microscopic description of the liver biopsy findings, which are classical for hepatocellular carcinoma. This tumor usually arises in a cirrhotic liver and, worldwide, hepatitis B infection is a major cause of cirrhosis. In such individuals, hepatitis virus DNA integration into host DNA can be demonstrated and is strongly suspected of having a role in the initiation of hepatocellular carcinoma. There are other factors that are also suspected of having a role but given this woman's medical history and the high prevalence of hepatocellular carcinoma in hepatitis B-positive populations viral-mediated oncogenesis is the most likely scenario.

Mutant Genes That Affect Several Organ Systems and Bodily Functions