Trisomy 13 in humans causes Patau syndrome and is usually a lethal condition. Retinoblastoma (RB) is an autosomal dominant type of childhood cancer caused by mutations in the RB gene on Ch 13. Consider a family in which a man with a very rare adult onset form of RB and a normal woman had two sons and a daughter. One son was karyotypically normal but had RB, the daughter had Patau syndrome and RB, and the second son had Patau syndrome but not RB. (Hint) Draw out the chromosomes with the appropriate alleles for RB on paper first. What are the genotypes and karyotypes of the mother and father? Describe one scenario explaining the cellular events by which the daughter might have arisen.