At one end of the spectrum are individuals who, except for mild anaemia, are symptom free. At the other, there are patients who have haemoglobin values in the 5-7 g/dL range and who develop marked splenomegaly, severe skeletal deformities due to expansion of bone marrow, and, as they get older, become heavily iron loaded because of increased intestinal absorption of iron. Recurrent leg ulceration, arthritis, folate deficiency, symptoms due to extramedullary haemopoietic tumour masses in the chest and skull, gallstones and a marked proneness to infection are particularly characteristic of this group of thalassaemias. Because
Table 6.3 ß-Thalassaemia intermedia.
Mild forms of ß-thalassaemia
Homozygosity for mild ß+-thalassaemia alleles
Compound heterozygosity for two mild ß+-thalassaemia alleles
Compound heterozygosity for a mild and more severe ß-thalassaemia allele
Inheritance of a- and ß-thalassaemia
ß+-thalassaemia with a0-thalassaemia (—/aa) or a+-thalassaemia (-a/aa or -a/-a) ß+-thalassaemia with genotype of HbH disease (—/-a)
ß-Thalassaemia with elevated y-chain synthesis
Homozygous ß-thalassaemia with heterocellular HPFH Homozygous ß-thalassaemia with Gy or Ay promoter mutations Compound heterozygosity for ß-thalassaemia and deletion forms of HPFH
Compound heterozygosity for ß-thalassaemia and ß-chain variants HbE/ß-thalassaemia
Other interactions with rare ß-chain variants Heterozygous ß-thalassaemia with triplicated a-chain genes (aaa) Dominant forms of ß-thalassaemia Interactions of ß and (Sß)+ or (8ß)°-thalassaemia of the heterogeneity of these disorders, it is possible to determine the course that is likely to evolve in an individual patient only by following the patient very carefully from early childhood. The haemoglobin constitution of the intermediate forms of P-thalassaemia is similar to that found in the major forms.
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