β Thalassaemic trait and systemic lupus erythematosus

The association between SLE and haemoglobinopathies has been poorly explored to date. Sixteen cases have been reported describing the coexistence of sickle cell disease3 and SLE, but only Kaloterakis et al reported a case of sickle cell/b ˚ thalassaemia in a patient with SLE.4 In this study we found a greater prevalence of an associated SS in patients with SLE and b thalassaemia than in those patients with SLE without b thalassaemia. The same finding has already been reported by Montecucco et al in patients with RA with b thalassaemia.5 Reasons for this association are at present unknown. Further studies of patients with different connective tissue disorders should be performed to exclude the possibility that the association is fortuitous. In addition to SS, all major systemic complications were more prevalent in b thalassaemia patients with SLE. It is unclear whether the increased presence of SSA antibodies among those with b thalassaemia may have some role6 or whether a more severe disease with persistently reduced C3 and C4 levels is typical of patients with b thalassaemia. Both an increased incidence of atherosclerotic events (secondary to the chronic hypercoagulable state7 or to the homocistinaemia 8 9) and a reduced ability to bind immune complexes10 have been described in b thalassaemia subjects and might be responsible for a more aggressive disease in these subjects. In conclusion, in contrast with other systemic rheumatic diseases (RA, in particular), the prevalence of b thalassaemia in patients with SLE seems to be lower than in the general population. However, when the two conditions coexist, SLE seems to have a more severe course and to be more frequently associated with SS.