Extended cytogenetic follow-up of patients with myelodysplastic syndrome (MDS).

The prognostic significance of clonal karyotype status in myelodysplastic syndrome (MDS) is assessed after an extended follow-up period of 5 years. There are three karyotype, single abnormalities or multiple abnormalities at the time of referral. However, there is no correlation between the size of the abnormal clone and prognosis. Karyotype status has independent prognostic significance in 'high risk' MDS so that patients with a refractory anaemia with excess of blasts (RAEB)/RAEB in transformation (RAEB-t) and a normal karyotype survive significantly longer than those with an abnormal karyotype (P < 0.001) and do not differ significantly from patients with refractory anaemia (RA). Significant differences in survival according to karyotype status are also seen in patients with chronic myelomonocytic leukaemia (P < 0.001) but not in those with primary acquired sideroblastic anaemia and RA. Among patients studied sequentially, those who retained a normal karyotype survived significantly longer than those who developed an abnormality on follow-up (P < 0.001). The risk of leukaemic transformation was also increased in patients who presented with or subsequently developed a clonal karyotype abnormality compared with those who remained normal (P < 0.05).