The autosomal dominant disorder neurofibromatosis Type I (NF1) causes benign tumors in individuals who have the NF1 allele (N). Nearly every individual who is either NN or Nn will show some clinical symptoms of the disorder yet individuals can have widely different symptoms with some individuals being severely affected while others have few tumors. Based on this description, NF1 appears to have ______________.
a) incomplete dominance
b) variable expressivity
c) incomplete penetrance
d) pleiotropy
Ans: b) variable expressivity
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Answer the following statement true (T) or false (F)