Galanello R, Cao A
Istituto di Clinica e Biologia dell'Età Evolutiva, Ospedale Regionale, Cagliari, Italy.
Ann N Y Acad Sci. 1998 Jun 30;850:325-33. doi: 10.1111/j.1749-6632.1998.tb10489.x.
Thalassemia intermedia encompasses a number of clinical conditions ranging in severity from beta-thalassemia carrier state to transfusion-dependent thalassemia major. The molecular bases of thalassemia intermedia, only partially defined, are very heterogeneous, but in general any factor able to reduce the globin-chain imbalance results in a milder form of thalassemia. These factors are the presence of a silent or mild beta-thalassemia allele, associated with a high residual beta-globin production, and the coinheritance of alpha-thalassemia or of genetic determinants that increase the gamma-chain production. Less frequent mechanisms are double heterozygosity for beta-thalassemia and triplicated alpha genes, and the presence of a hyperunstable hemoglobin variant. However, for a consistent number of beta zero-thalassemia homozygotes with a thalassemia intermedia phenotype the modifying factor has not been defined yet. In contrast, there are simple beta-thalassemia carriers who, for unknown reasons, have an unusually severe clinical phenotype.
中间型地中海贫血包括一系列临床病症，严重程度从β地中海贫血携带者状态到依赖输血的重型地中海贫血不等。中间型地中海贫血的分子基础仅部分明确，非常异质，但一般而言，任何能够减少珠蛋白链失衡的因素都会导致症状较轻的地中海贫血形式。这些因素包括存在一个沉默或轻度β地中海贫血等位基因，与高残留β珠蛋白产生相关，以及α地中海贫血或增加γ链产生的遗传决定因素的共同遗传。不太常见的机制是β地中海贫血的双重杂合性和α基因的三重复制，以及存在高度不稳定的血红蛋白变体。然而，对于相当数量具有中间型地中海贫血表型的β0地中海贫血纯合子，其修饰因子尚未明确。相比之下，有一些单纯的β地中海贫血携带者，原因不明，却具有异常严重的临床表型。
