Answer AND Explanation:
In man, codominance is seen in the inheritance of the ABO blood group alleles. the trait is controlled by more than two alleles for the same gene within a population. Such alleles are called multiple alleles and they occupy the same locus on homologous chromosomes.
Sickle cell anaemia is a disease of the humans which is inherited in an incomplete dominance way. The disease is transmitted through a recessive gene that leads to the synthesis of abnormal haemoglobin. In sickle cell anemia patients, haemoglobin A is entirely replaced by a different type called haemoglobin S.