Biology of Humans 4th Edition by Judith Goodenough,Betty McGuire

Exercise 12

George and Sue have an infant, Sammy, who is lethargic, is vomiting, and has liver disease. Sammy is diagnosed with galactosemia, an autosomal recessive disorder in which the affected individuals are unable to metabolize the milk sugar galactose. Sammy is placed on a diet free of lactose and galac- tose and slowly recovers. George and Sue would like to have a second child. What are the chances that the second child will have galactosemia? (Hint: What are the genotypes of George and Sue? Use a Punnett square to determine the expected results of a cross with those genotypes.)