29. Heredity

Most children with cystic fibrosis are born to normal parents. Children with cystic fibrosis are homozygous for the recessive gene (cc). What can you conclude about the genotypes of the normal parents?

A genetic counselor has been consulted by a couple that is concerned about a dominant form of syndactyly (fused fingers or toes) in the male partner, Paul. Paul has syndactyly, as do his three brothers. His mother, his maternal grandparents, and his paternal grandfather do not have syndactyly, but his father and paternal grandmother do. The counselor constructs a pedigree spanning three generations for Paul’s family. Draw this pedigree and show the phenotype and genotype for each person.