sickle cell anaemia is a here is a hereditary disease due to a recessive gene which changes normal haemoglobin (Hb-A) to abnormal haemoglobin (Hb-S). The red blood cells of people with sickle cell anaemia or sickle shaped. What are the possible phenotypes of the offspring of a man who is also heterozygous? Show your working
The man is heterozygous for sickle cell anaemia, meaning he has one normal allele (Hb-A) and one abnormal allele (Hb-S). Let's represent this using the letters A (normal allele) and S (abnormal allele).
Possible genotypes of the man:
- AS
Possible genotypes of the woman:
- AS
Now let's determine the possible combinations of alleles for their offspring:
- AA (25% chance): Normal haemoglobin, no sickle cell anaemia
- AS (50% chance): Carriers of the sickle cell trait, do not have sickle cell anaemia
- SS (25% chance): Have sickle cell anaemia
Therefore, the possible phenotypes of the offspring are:
- 25% chance of no sickle cell anaemia (AA)
- 50% chance of being carriers of the sickle cell trait (AS)
- 25% chance of having sickle cell anaemia (SS)