Thalassemia is highly prevalent in Taiwan, but limited data are available about the association between genotypes and clinical manifestations in Taiwanese patients with Hb H disease. Here, we studied α-globin gene abnormalities and clinical features in Taiwanese patients with Hb H disease. Of the 90 patients, sixty-four (71.1%) were deletional and twenty-six (28.9%) were nondeletional Hb H disease. The () type of -thalassemia mutation was detected in the majority of patients (>95%). The most common genotype was (), followed by (). After further investigation of the genotype-phenotype correlation in 68 patients, we found that patients with nondeletional Hb H disease had more severe clinical features than those with deletional Hb H disease, including younger age at diagnosis, more requirement of blood transfusions, and larger proportion of patients with splenomegaly, hepatomegaly or jaundice. This is probably a consequence of the lower hemoglobin levels and the higher Hb H levels. The clinical severity was highly variable even among patients with an identical genotype, and the diversity was much more profound among patients with () genotype. Therefore, predicting the phenotype directly from the genotype in Hb H disease remains relatively difficult in Taiwan.
