John has thalassemia major. Both of John’s parents have normal red blood cells. John also has a brother and a sister, but neither have been tested for the thalassemia trait. John’s wife, Linda, has normal red blood cells. Both of Linda’s parents have normal red blood cells. Linda’s maternal grandfather (her mother’s father) has normal red blood cells, while her maternal grandmother (her mother’s mother) has the thalassemia trait. Linda’s fraternal grandfather (her father’s father) had thalassemia major, while her fraternal grandmother (her father’s mother) had normal red blood cells. Once the pedigree is assembled, label the genotypes of each individual using a capital “T” to represent the dominant allele and a lower case “t” to represent the recessive allele and create a key to identify which version is the thalassemia allele. If more than one genotype is possible for an individual, list all possible genotypes.
