Iron deficiency anemia interfering the diagnosis of compound heterozygosity for Hb constant spring and Hb Paksé: The first case report

Combined heterozygosity for hemoglobin Paksé, α-thalassemia and for hemoglobin E, β- thalassemia ̵ first appearance in Europe

Hemoglobinopathies are among the most common inherited diseases and they are believed to be one of the major etiologic factors contributing to anemia. Thalassemia is characterized by an altered hemoglobin (Hb) chain synthesis and may appear as alpha-(α-)thalassemia and/or beta-(β-)thalassemia. The clinical manifestations of thalassemia may range from asymptomatic to severe, with the potential to ultimately result in death. The search for an underlying cause was prompted by the discovery of an asymptomatic patient of Thai origin with microcytic anemia and no iron deficiency during a routine hematological examination. Genetic sequencing results revealed Hb Paksé, α2 CD 142 [A > T] (HBA2:c.429 A > T) and HbE β2 CD 26 [G > A] (HBB: c.79 G > A). It is essential that the identification and knowledge of Hb mutations facilitate the clinical recognition, genetic testing, and counseling of patients with thalassemia. The combination of two thalassemia Hb variants, one in the α-globin gene as Hb Paksé and one in β-globin gene as Hb E, in a single individual is occasionally described in East Asia. The first appearance of combined heterozygosity for Hb Paksé, and Hb E in Europe provides evidence that this is the result of a migration-caused occurrence.

Twelve Cases of Hb Manitoba [α102(G9)Ser→Arg]: the Fluctuation in the Variant Expression

Hb Manitoba [α102(G9)Ser→Arg] is a rare α chain variant with diverse ethnic origins. It is mildly unstable with an expression of around 10.0-14.2% in the heterozygous state in most literature. In this study, 12 cases of Hb Manitoba [11 cases carried Hb Manitoba II (HBA1: c.309C>A) and one case carried Hb Manitoba IV (HBA1: c.307A>C)] were detected during a wide-spectrum study of α chain variants in the UK. Fluctuation in variant expression from 6.9 to 15.2% of total Hb on high performance liquid chromatography (HPLC) would pose a diagnostic dilemma in routine laboratories. Focusing on the variant expression, the median of Hb Manitoba was around 11.5% of total Hb in three cases, apparently with normal hemoglobin (Hb), and normal red blood cell (RBC) indices. Two cases showed a higher expression (13.9 and 15.2%) and five cases showed a lower expression (6.9-9.9%). The common α-thalassemia (α-thal) -α^3.7 (rightward) deletion coexisted with one case of increased Hb Manitoba expression. Iron (or other nutrient) deficiency was likely the cause of decreased Hb Manitoba percentage in this study. The α73(EF2)Val→Val (α2) (HBA2: c.222G>T) polymorphism is published for the first time and coexisted with two cases. The Cap +14 (C>G) (HBA2: c.-24C>G) polymorphism coexisted with another case in a heterozygous state. In conclusion, the fluctuation in variant expression can cause a diagnostic dilemma, especially in routine laboratories. Screening for the common -α^3.7 deletion and iron deficiency is recommended when an α chain variant is suspected.

Iron deficiency anemia interfering the diagnosis of compound heterozygosity for Hb constant spring and Hb Paksé: The first case report

BACKGROUND

Diagnosis of thalassemia or hemoglobinopathy concomitant with iron deficiency anemia (IDA) is challenging.

METHOD

We report a case of 43-year-old female whose diagnosis of compound heterozygosity for hemoglobin Constant Spring (HbCS) and Hb Paksé became apparent after the treatment of IDA.

RESULTS

Prior to treatment, Hb analysis using isoelectric focusing (IEF) showed HbA 95.6%, HbA₂ 2.7%, and HbCS 1.7% compatible with heterozygous HbCS. After 4 months of oral iron therapy resulting in an improved Hb level, her HbCS level was substantially increased to 8.7% on IEF suggesting homozygous HbCS. Subsequent DNA analysis using multiplex amplification refractory mutation system analysis revealed compound heterozygosity for HbCS and Hb Paksé.

CONCLUSION

This case demonstrated that IDA can significantly reduce HbCS/Hb Paksé levels and probably mask the diagnosis of homozygous HbCS, homozygous Hb Paksé or the compound heterozygosity for both hemoglobinopathies by hemoblogin analysis. The test should be repeated after resolution of IDA, or molecular testing should be performed to confirm the diagnosis.