Moreover, a low amount of maternal cell contamination in the fetus specimen for the prenatal diagnosis of hemoglobin Barts hydrops fetalis as well as the rare multiplicated α-globin genes can be identified using this method.
Mutations at the alpha-globin locus are the most common class of mutations in humans, with deletion of all four adult alpha-globin genes resulting in the perinatal lethal condition haemoglobin Barts hydrops fetalis.
The number of alpha-globin chains in the HbA molecule, and the absence as well as the varied forms of alpha thalassemia are inherited quantitatively as follows: four alpha-globin chains and the absence of alpha thalassemia result from GbGbGcGc; either GbGbGcOc or GbObGcGc yields three alpha-globin chains and asymptomatic alpha thalassemia minor; any one of three genotypes, GbGbOcOc, GbObGcOc or ObObGcGc, yields two alpha-globin chains and mild alpha thalassemia minor; either GbObOcOc or ObObGcOc yields one alpha-globin chain and severe alpha thalassemia minor; ObObOcOc produces no alpha-globin chain and the fetal alpha thalassemia major.