Genotype-phenotype correlation in Iranian patients with Hb H disease.

Thalassemia is the most common genetic disorder in Iran. Some α-globin genotypes leading to Hb H disease may cause severe anemia and dependence on regular blood transfusions. In this study, 40 patients were analyzed for the molecular basis and the genotype-phenotype correlation of Hb H disease in Iran. α-Globin molecular analysis was performed by polymerase chain reaction (PCR) followed by agarose gel electrophoresis, reverse hybridization test strips or DNA sequencing. The most frequently observed α-globin genotypes were -α(3.7)/- -(MED) in 10 patients (25%), - -(20.5)/α(-5nt)α in six patients (15%) and - -(20.5)/-α(3.7) in four patients (10%). A subset of the identified Hb H genotypes, including - -(MED)/α(CS)α, - -(MED)/α(PolyA2)α and α(CS)α/α(CS)α, was associated with a need for regular or irregular blood transfusions. Our findings provide a basis for predicting phenotype severity by identifying the Hb H genotype and making more selective decisions for prenatal diagnosis.