Hillary is 8 years old and has neuronal ceroid lipofuscinosi…
Hillary is 8 years old and has neuronal ceroid lipofuscinosis, also known as Batten disease. It is autosomal recessive, and its symptoms include vision loss, loss of coordination, dementia and seizures. Her younger brother Alex is 6 years old and is healthy, as are her parents and grandparents. Given what you know about the mode of inheritance and their phenotypes, Hillary’s parents must be and their genotype must be . Draw out a Punnett square with Hillary’s parents genotypes. If they have another child, the chance that the child has Batten disease is . The chance that the child is a carrier is . The chance that the child is healthy and not a carrier is . Think about Hillary’s brother Alex who is healthy and does NOT have Batten disease. Given that he is healthy, Alex’ genotype can NOT be . With this information, the remaining genotype options for Alex indicate that he has a of being a carrier for Batten disease.