1) Retinoblastoma, a malignant tumor of the eye, can be inherited as an autosomal dominant
trait. Penetrance in such families is 80% (4/5’ths). Ms. R’s paternal grandmother, father,
and brother had retinoblastoma, but Ms. R herself is unaffected. She is 12 weeks
pregnant. What is the risk of retinoblastoma in Ms. R’s fetus?