8. Imagine that a geneticist has identified two disorders that appear to be caused by the same chromosomal defect and are affected by genomic imprinting: blindness and numbness of the limbs. A blind woman (whose mother suffered from numbness) has four children, two of whom, a son and daughter, have inherited the chromosomal defect. If this defect works like Prader-Willi and Angelman syndromes, what disorders do this son and daughter display? What disorders would be seen in their sons and daughters?
In Prader-Willi and Angelman syndromes the type of symptom exhibited in the offspring depends upon which parent contributes the defective chromosome.
In this case children receiving a defective chromosome from the father will suffer from numbness and children receiving a defective chromosome from the mother will be blind.
The pedigree below helps to sort out how the imprinting works.