[Alpha-thalassemia with Hb G-Philadelphia incidentally discovered during HbA1c testing]

Hemoglobin G-Philadelphia is an alpha-globin chain variant resulting from the substitution of asparagine by lysine at position 68 [α68(E17) Asn→Lys]. This hemoglobin (Hb) variant is generally clinically silent; however, its identification may be challenging, particularly when present in the homozygous state and co-inherited with the -α3.7 deletion. We report the case of a 28-year-old woman from southeastern Morocco presenting with refractory hypochromic microcytic anemia (Hb 10,6 g/dL, MCV 60.5 fL, MCH 20.3 pg). Owing to a family history of type 2 diabetes mellitus, HbA1c testing was performed and revealed a hemoglobin variant eluting in the D window (87.44 %) on the Bio-Rad D-100 HPLC system. Further laboratory investigations (HPLC Variant II, capillary electrophoresis, and acid pH gel electrophoresis) confirmed the presence of homozygous Hb G-Philadelphia. Molecular analysis confirmed the variant and demonstrated its association with mild α-thalassemia. Family study revealed that the daughter is a heterozygous carrier of Hb G-Philadelphia and a cis -α3.7 α-thalassemia trait.