We describe an insertion variant on the α1-globin gene (HBA1) identified in a 49-year-old woman of Jurassian ancestry presenting with macrocytosis and erythrocytosis. The variant resulted in a peak of 15.5% of the total hemoglobin (Hb) on high performance liquid chromatography (HPLC). Stability and oxygen affinity testing revealed that the variant was stable and had an increased oxygen affinity. Molecular genetic testing detected the heterozygous sequence variant Hb Bakersfield [α50(CE8)His→0; Arg-Ser-His- inserted between 49(CE7) and 51(CE9) of α1; HBA1: c.151_152insGGAGCC (p.Ser50_His51insArgSer)] in the index patient, one of her sons, as well as in two of her grandchildren, who showed a similar hematological pattern.
Keywords: Erythrocytosis; HBA1; Hb Bakersfield; insertion; oxygen affinity; p50.