Reference no: EM133497393

Case: Huntington disease is a progressive brain disorder that causes uncontrolled movements and reduced cognition over time. Huntington's is inherited in an autosomal dominant manner. Many couples who have a family history of this disorder seek out the help of a genetic counsellor to determine their probability of producing affected children.

Grayson and Anna are considering starting a family. However, Huntington disease is known to run in Grayson's family. His grandfather, Earl, had the disorder, and passed it on to Grayson's mother, Emily. Emily is one of three children produced by Earl and his wife, Christina. She is the only affected child. Grayson's father, Matthew, does not have Huntington's. Anna does not have any family history of Huntington's, and Grayson has not shown any signs of the disorder.

a) Construct a pedigree to represent the transmission of the Huntington's trait through Grayson's family tree. Indicate the genotype of each individual in your diagram using "H" to represent the dominant allele, and "h" to represent the recessive allele.

b) Based on the information provided, what is the probability that Grayson and Anna will have an affected child? (Use a Punnett Square to illustrate your answer)