Answer to Question #349722 in Genetics for Vasuki

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

Hb^A - normal hemoglobin allele, Hb^S - abnormal hemoglobin allele. The heterozygotes for the sickle cell anemia allele (Hb^AHb^S) cross will lead to the birth of 50% heterozygous offspring with subclinic anemia (Hb^AHb^S), 25% homozygotes (Hb^AHb^A) without sickle cell trait and 25% homozygotes (Hb^SHb^S) with sickle cell anemia. Thus, in a family, in which both parents are stable to malaria (heterozygous for sickle cell anemia, Hb^AHb^S), the probability of giving birth to children susceptible to malaria (homozygous for the normal hemoglobin allele, Hb^AHb^A) will be 25%.