Answer to Question #147143 in Genetics for Vaith

Question

Sickle cell anemia (S-anemia) is inherited as autosome incomplete dominant character. Homozygotes for dominant character die before puberty, the heterozygotes have subclinic anemia. The plasmodium can not use the S-hemoglobin and human with S-anemia has no malaria. What is the probability of the birth of children not stable to malaria, in a family, in which both parents are stable to malaria.

Answer 1

A cross between parents heterozygous, that is Ss for the sicle cell trait, stable from malaria will result into the birth of 3 offsprings with the sickle cell trait and one child without the sickle cell trait; that is 1SS, homozygote for the dominant trait, 2Ss, heterozygote for the sickle cell trait and 1ss, that completely lacks the sickle cell trait. Hence, the probability of giving birth to children unstable to malaria will be 1/4 or 0.25 in the F1 generation.