In cases in which the beta-thalassemia trait is associated with other features, the molecular lesion has been found either in the gene encoding the transcription factor TFIIH (beta-thalassemia trait associated with tricothiodystrophy) or in the X-linked transcription factor GATA-1 (X-linked thrombocytopenia with thalassemia) [14,15]. This evidence concerns the gene GATA1 and beta thalassemia.