Answer to Question #147144 in Genetics for Vaith

Question

Sickle cell anemia (S-anemia) and thalassemia are inherited as the incomplete autosome dominant characters. The genes of these diseases are non-linked. The heterozygous for S-anemia and thalassemia individuals do not have clinical symptoms. The carriers of S-anemia or thalassemia do not affect malaria. The diheterozygotes have crescent anemia. The homozygous for S-anemia and thalassemia individuals die in childhood. Determine the probability of the birth of healthy children in the family, in which one parent is heterozygous for both characters, and another is homozygous recessive.

Answer 1

In this type of cross, the F1 generation will produce a summary the following offsprings; 4 children all homozygous normal for both the traits, 4 diheterozygous individuals for both traits, 4 individuals normal for the sickle cell trait but heterozygous for thelasemia trait, and finally, 4 individuals normal for thelasemia but heterozygous for the sickle cell trait, hence more or less carriers for thalasemia trait. Since heterozygous individuals for both the traits show no clinical symptoms, all the F1 generation children are considered healthy for the diseases that are as a result of the two traits, hence the probability of healthy children in this family will be 12/16, that is 0.75.