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.