The gene for sickle-cell anaemia in homizygous condition is lethal and produces sickle cell trait in heterozygous carrier. Explain.

Explanation

The disease sickle cell anaemia is caused by a gene ` Hb^(S)` . Normal or healthy gene `Hb^(A)` . Is dominant The carriers (heterozygotes ` -Hb^(A)//Hb^(S))` Show signs of mild anaemia. They are said to have sickle -cell trait. The homozygotes with recessive gene `Hb^(s)` however, die of fatal anaemia. Thus, the gene for sickle cell anaemia. Thus, the gene for sickle cell anaemia is lethal in homozygous conditions and produces sickle - cell trait in heterozygous carrier.