Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal disorder characterised by an unusual sensitivity of abnormal red cell population(s) to complement lysis, due to a complete or incomplete defect of various surface molecules, including CD55 and CD59. PNH has been associated with various hematological disorders. Using a newly introduced method, the Sephacryl gel test microtyping system, we investigated the presence of CD55 or CD59 defective red cell populations in several hematological disorders. It was also found that a large proportion of such patients possess CD55 deficient populations, while a smaller but still significant proportion possess CD59 deficient populations. Defective red cell populations were detected in normal subjects as well. These findings need further investigation. Nevertheless the Sephacryl Gel Test microtyping system although non specific, seems to be useful in screening for the PNH and/or "PNH-like" red cell defect in several hematological disorders.
Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative diseases that carry intrinsically the potential for leukemic transformation. The aims of this study were (1) to detect involvement of N- and K-ras mutations in codons 12 and 13 in the pathogenesis of the chronic and blastic phases of PV and ET, (2) to study the occurrence of microsatellite instability (MSI) in chromosomes 5 and 7 during the chronic phase and blastic transformation of the disease, and (3) to examine the incidence of leukemia in patients treated with hydroxyurea (HU). Samples of PV and ET patients were analyzed with a polymerase chain reaction. No N- or K-ras mutations were detected. A positive score for MSI in chromosome 7 was found in 1 patient with PV during leukemic transformation. Three of 69 patients developed acute myelogenous leukemia, 2 with PV and 1 with ET. As of this report, the overall incidence of leukemic transformation is 5.7% (2/35 patients) in PV and 3.3% (1/30 patients) in ET patients treated with HU. These results indicate that (1) MSI is a genetic marker that can be detected, even in a small group of patients, at the blastic phase of the disease and (2) no increased leukemogenicity was noted in this group of patients treated with HU.
A case of adult osteopetrosis Type I was diagnosed in a 22‐year‐old female. She presented for investigation of anaemia with ‘myelophthisic’characteristics and extramedullary haemopoiesis which was resistant to haematinics, nandrolone and low‐dose corticosteroids. She became progressively transfusion‐dependent with gradually worsening thrombocytopenia. She was successfully treated with recombinant erythropoietin. Anaemia as well as thrombocytopenia were corrected. There appeared to be a synergistic action of erythropoietin with steroids.
Trisomy 8 is the most common numerical chromosomal abnormality in myelodysplastic syndromes (MDS). Paroxysmal nocturnal haemoglobinuria (PNH) is an aquired haemolytic anaemia, clonal in nature, due to somatic mutation. PNH may evolve to aplastic anaemia, to MDS or to acute myeloid leukaemia. We present a patient who had trisomy 8 mosaicism at disease presentation who received therapy with all‐trans‐retinoic acid, responded to therapy, and developed PNH in the course of the disease. Cytogenetics at the time of PNH diagnosis showed a normal karyotype.
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