How does One get The Disease?

Everyone has a genotype resulting from a combinationof haemoglobin from both parents. Haemoglobin strands are designated as: HBA, HBC, HBS, etc. The commonest haemoglobin disorder found in Africa is the 'S' haemoglobin (HBS). Other types are not as common and do not give rise to major health problems as HBS. HBC is the next common HB disease found in Africa. The normal HB strand is the HBA.

A person inherits two strands of HB from his parents so each individual has two identical or non-identical HB forms. Generally, HB forms are AA, AS, SS, SC, CC, and so on. In the context of this discourse, we would consider the likely outcomes from combinations of the first three forms, which are predominant in Nigeria.

Common Genotypes:

GENE       TYPE         DESCRIPTION
   AA          Normal      The person with this type of gene has normal blood.
   SS         Sickler        The person is a sickler.
   AS         Trait           The person has sickle cell traits but will be healthy as the HBA balances the                                       effect of the HBS.

It is worthy of note that a child born of a couple each having the trait (Gene AS) may result in Gene SS, this is sickle cell anaemia. The scheme below presents all probable outcomes from the three Genotypes.

Chance Occurrence Of Genotype In The Offspring

Combination 1: AS-to-AS	Combination 2: AA-to-AS
Combination 3: AA-to-AA All the children born of AA-to-AA parents will have Normal (AA) gene.	Combination 4: SS-to-SS In an SS-to-SS union, all the children will be Sicklers .
Combination 5: AA-to-SS In an AA-to-SS union, all the children will be Carriers .	Combination 6: AS-to-SS