Sickle cell anaemia is an inherited blood disorder in which there is not much available red blood cells to carry oxygen.
The individual is homozygous recessive because such inherited the two deleterious allele SS.
For an individual to have inherited sickle cell anaemia from the parents, it means the two parents are carriers.
The father have AS gene and the mother have AS gene which is the carrier of sickle cell anaemia gene, the individual inherited the deleterious alleles from the phenotypically normal parents.
The parents of the individual displaying the sickle cell anemia (SS) are phenotypically normal parents meaning, both parents are carriers of the (AS) gene which is a recessive trait for sickle cell anemia.
The individual took up the SS allele from both parents which makes him/her homozygous recessive. An individual is said to be homozygous recessive if that individual carries two copies of the same recessive allele.
Homozygous dominant is when an individual carries two copies of the same dominant allele (e.g AA).
