Chromosome 16 contains the genetic codes for the zeta and alpha hemoglobin chains.
Each chromosome has two loci alpha chains α1 and α2. This equals four gene loci coding for the alpha hemoglobin chain. See the image for a visual representation of these loci.
In the genotypic notation of alpha thalassemia an "α" represents the presence of an alpha locus. A "-" represents a deletion of a locus.
The notation for the normal number of alpha loci is αα/αα.
As mentioned, alpha chains are found in Hb F and Hb A. The amount of Hb A in an unaffected adult is typically 95–98%.”
