Monosomy 7 in childhood: a myeloproliferative disorder

Between 1976 and 1979 a myeloproliferative disease associated with cells monosomic for chromosome number 7 in the bone marrow was seen in six boys aged 5 1/2 months to 8 years (median 10 months). Presenting features included hepatosplenomegaly (5/6), respiratory infections (4/6), pallor (2/6) and skin infections (1/6). Haematological features included a leucoerythroblastic anaemia with leucocytosis and thrombocytopenia, and a hyperplastic marrow with a slight excess of blasts. Fetal haemoglobin was normal in four patients and mildly raised in the other two. Neutrophil function tests showed defective chemotaxis with reduced killing, despite a normal NBT test. Cytogenetic analysis of the marrow showed a preponderance of cells with monosomy 7; the blood lymphocytes were cytogenetically normal. In three patients the disease progressed to acute myeloid leukaemia (AML) after 3 weeks to 23 months; the only patient who remitted did so in response to 6-mercaptopurine and prednisolone, but relapsed 16 months later. A fourth child developed massive splenomegaly which initially responded to 6-mercaptopurine and prednisolone, but progressed to myelofibrosis 11 months later. A fifth child died from anaemia and respiratory infection without progression to leukaemia and the sixth patient has not yet developed leukaemia. Monosomy 7 is the diagnostic criterion of one of the more common myeloproliferative states in childhood and carries a high risk of progression to AML. The acute phase is usually resistant to chemotherapy, but even in responsive cases treatment does not result in elimination of the abnormal clone. Allogeneic bone marrow transplantation should be considered in cases with a suitable donor.