Hb Oegstgeest [α104(G11)Cys → Ser (α1)]. A New Hemoglobin Variant Associated with a Mild α-Thalassemia Phenotype

Abstract

A microcytic hypochromic anemic state was observed in an 8-year old Black female of Surinam origin during pre-operative Hb S [β6(A3)Glu → Val] screening. Her high zinc protoporphyrin (ZPP) level suggested a chronic iron depletion but, in contrast, the high red blood cell (RBC) count (5.85 × 10¹²/L) was indicative of a possible coexisting thalassemia. No abnormal hemoglobin (Hb) bands were present on high performance liquid chromatography (HPLC) or alkaline electrophoresis and the Hb A₂ level was normal. Break point polymerase chain reaction (PCR) failed to reveal any of the common α-thalassemia (thal) mutations but selective DNA sequencing of both α-globin genes disclosed a TGC →AGC transversion at codon 104 of the α1 gene. Cystine at codon 104 is involved in α/β globin contact and has been described to be a critical amino acid of the α2 chain when substituted by a tyrosine (Hb Sallanches), inducing Hb H (β₄) disease in the homozygous state. Our heterozygous patient had a moderate anemia of 12.2 g/dL and a borderline haptoglobin suggesting some degree of hemolysis.

• Abnormal hemoglobin (Hb)
• α Chain