|| homozygous Hb Crete
|| Heterozygous Hb Crete
|| Normal hemoglobin
is a SNP for the Hemoglobin beta HBB
gene, which is responsible for the protein beta-globin, a component of hemoglobin inside red blood cells. Usually, hemoglobin contains two subunits of beta-globin and two subunits of alpha-globin. Variations in the HBB gene can be unnoticeable, while others may affect a persons health, resulting in various hemoglobin disorders such as beta thalassemia, sickle cell disease, and hemoglobin C.
In 1979, a new mutant hemoglobin with high oxygen affinity was discovered in a Greek family and called Hemoglobin Crete [PMID 36184], but the patients were heterozygous only for Hb Crete and often also had mutations for beta-thalassemia which affects the same gene. This mutant Hb was identified as resulting from a Ala129Pro missense mutation in HBB and identified by sequencing as rs34139813 (G->C) [PMID 15658190]. In 2005, a homozygous Hb Crete individual without any additional beta-thalassemia mutations was identified [PMID 15885607].
The Hb Crete phenotype (both homozygous and heterozygous) is associated with erythrocytosis and microcytosis. Hb Crete patients may have functional anemia, with a thalassemic-like phenotype as a result of a deficit of beta-globin chains. Patients may also have elevated cardiac output ultimately leading to cardiac insufficiency [PMID 15885607].
[PMID 11300350] Hb Mont Saint Aignan [beta128(H6)Ala-->Pro]: a new unstable variant leading to chronic microcytic anemia.