Prevalence of erythrocyte haemoglobin H inclusions in unselected patients with clonal myeloid disorders.

Patients with clonal myeloid disorders, especially myelodysplastic syndromes (MDS), may acquire alpha-thalassaemia. To estimate the prevalence of this erythrocyte phenotype, we examined brilliant cresyl blue-stained blood smears from 201 patients with neoplastic myeloid disorders and 282 controls (195 non-clonal anaemia, 62 with medical illnesses without anaemia and 25 healthy persons). Haemoglobin H inclusions were detected in 8/100 patients with MDS (8%) and 2/81 (2.5%) patients with myeloproliferative disorders, but in none of the acute leukaemia patients or controls. We conclude that the emergence of thalassaemic clones may be relatively common in the disordered marrow milieu of MDS.