The association of anaemia and haemoglobinuria as a clinical syndrome was first recognized goyearsago by P. Strubing. By the 1930s there had been some 28 papers describing the clinical features of PNH, including the classical papers by Hijmans van den Bergh (1911) and Marchiafava & Nazari (1911). Dacie's first contribution was made in 1938, when, in a paper with Israels and Wilkinson, he gave a detailed description of the case of a 34-yr-old woman investigated in 1937 at the Manchester Royal Infirmary, and who was recognized as having PNH by the presence of anaemia of a chronic haemolytic type, persistent haemoglobinaemia, haemoglobinuria which was predominantly nocturnal, and persistent haemosiderinuria. Dacie carried out extensive serological studies on this patient. He noted autohaemolysis of whole blood allowed to clot at 37°C and demonstrated that the patient's red cells underwent lysis when incubated at 37°C with her own serum as well as with normal serum at a pH of 7.0-7.2; he speculated that the clinical picture of severe haemolytic anaemia was due to an abnormality of the red cells that made them sensitive to a thermolabile lytic agent present in serum. These observations, made independently at about the same time as those of Ham (1937), formed the basis for the acidified-serum lysis test which became recognized as a diagnostic test for PNH. The effect of pH on in vitro lysis of PNH red cells was further studied by Dacie & Richardson in 1943 ; they confirmed that lysis was maximal at pH 7.2, while it was inhibited when the pH was above 8 or below 6. Dacie's interest in PNH continued, so that in a paper published in 1963 (Dacie, 1963) he was able to review 48 patients who had been referred to himover a 17-yr period; by the present time (1g71), 73 patients have been investigated at the Royal Postgraduate Medical School (Fig I).In reviewing this large series it becomes apparent that PNH is a broadly-based eponym which represents a wide spectrum. At one end is the classical form of PNH: a small percentage of these cases had a typical presentation with severe haemolysis associated with haemoglobinuria which was, at least in some cases, characteristically nocturnal in rhythm. In other cases haemoglobinuria has been transient or did not occur at all. Some patients presented with somewhat more obscure forms of anaemia or with symptoms referable to the complications of the disease, namely, abdominal pain, venous thrombosis, headache, jaundice, irondeficiency, thrombocytopenic purpura and aplastic anaemia. In some cases there were marked hyperplasia of the bone marrow, high reticulocyte count, and normal or almost normal leucocyte and platelet count. More frequently, there has been a variable degree of impairment of marrow function, resulting in leucopenia, thrombocytopenia and reticulocytopenia; at times this has been only slight or moderate; at other times there has been severe pancytopenia.The various manifestations of a complex relationship of PNH and aplastic anaemia have
