Coexistence of three hemoglobins with different alpha-chains in two unrelated children (with family studies indicating polymorphism in the number of alpha-globin genes in the Sardinian population)

In each of two families from Sardinia, Italy, we have found segregation for two alpha-chain hemoglobin variants, which we have identified as G Philadelphia [alpha 68 (E17) Asn leads to Lys] and J Sardinia [alpha 50 (CE8) His leads to Asp], respectively. One family also shows segregation for the beta-thalassemia trait. One subject in one family and two subjects in the other family have in their red cells both hemoglobin variants, G and J, in addition to HbA. One of the subjects, a newborn baby, has six major hemoglobin components; alpha 2A beta 2, alpha 2A gamma 2, alpha 2G beta 2, alpha 2G gamma 2, alpha 2J beta 2, alpha 2J gamma 2. These three cases are to be added to three previous cases in the literature in whom three different alpha-chains have been found in the same blood. These findings prove that the alpha-chain locus is duplicated in the Sardinian population, as it is in other populations. The relative amounts of the various hemoglobin species found in members of our two families, through three and four generations respectively, suggest that chromosomes with and without duplication may coexist in the same population.