Most of these occur within the PH domain however substitutions located within the SH2 domain have also been described in patients with a variety of diseases including the myeloproliferative neoplasms, a group of disease characterised by excessive JAK-STAT signalling resulting in hyperplasia of specific mature blood lineages11,13,20,38,39 and idiopathic erythrocytosis40,41 (Fig. 5a). This evidence concerns the gene SOAT1 and myeloproliferative disorder.