The Importance of the Genetic Picture and Globin Synthesis in Determining the Clinical and Haematological Features of Thalassaemia Intermedia

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Abstract
Summary. Twelve carriers of thalassaemia intermedia were studied. Their clinical and haematological picture was distinctly different from that in both heterozygotes and haematological picture was distinctly different from that in both heterozygotes and homozygotes for β thalassaemia. Several genetic patterns were found responsible for thalassaemia intermedia: β/δβ thalassaemia, α2β/β thalassaemia, β/β thalasaemia-heterocellular HPFH. In a few subjects the genetic picture indicated that the patients were homozygous for β thalassaemia, in spite of the mildness of the clinical sitution. The lack of genetic uniformity was reflected in very wide Hb A2 (2.5–8.7%) and Hb F (7.5–96.9%) ranges, as opposed to the noticeable degree of biochemical uniformity indicated by the very similar imbalance of globin chain synthesis: 0.33–0.54 for the non-α/α chain ratio in the peripheral blood. The mean for this parameter (0.43 ± 0.05) was significantly different (P<0.001) from that observed in heterozygous carriers (0.60 ± 0.10) and homozygous carriers (0.11 ± 0.05) for β thalassaemia. The marrow blood displayed a comparable pattern. It is therefore suggested that the severity of thalassaemia is attributable to the degree of chain synthesis imbalance.
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