MANY different imitations giving rise to anaemia in mice have now bccn rcportcd and their genctic and hacmatological features have recently been reviewed (Russell and Bcrnstein, I 966; I'inkerton and Bannerman, 1967). In some instances, such as the hereditary spherocytosis of the deer mouse and the autoimmune hacmolytic anaemia of the NZUjB1 strain of house mouse, they mimic human disorders, and their study offers the possibility of insight into mechanisms of human disease. Other mutants provide the opportunity to isolatc and study single, genetically-controlled, steps in haemopoiesis. Sex-linked (or, preferably, X-linked) anaemia of mice (gene symbol, sla) first appeared in the male offspring of the daughter of a male who was irradiated with 5 0 0 r. of X-rays, and this finding and the results of subsequent linkage studies were reported by Falconer and Isaacson (1962). Grewal (1962) gave a general description of the anaemia and compared it with thalassaemia. We have reported preliminary findings on the nature and mechanism of the anaemia Cooper, 1964, 1966; Pinkerton, Kreimer-Uirnbaum and Bannerman, 1966), and we now describe in detail the haematological findings, including the effects of age and various forms of treatment, and discuss possible analogies between X-linked mouse anaemia and the human hypochromic anaemias.
MATERIALS AND METHODSThc mice studied were descendants of a small breeding stock from a mixed strain, kindly presented by Dr. D. S. Falconer. Most of the investigations reported here have been carried out on animals inbred from the original stock by brother-sister matings. It has sometimes been necessary to use as controls normal first generation hybrid males from crosses with the inbred C~7B1/6 Jax strain; this has been occasioned by the presence in our original stock of the X-linked mutation, 'Brindled', lethal shortly after birth in the male, in repulsion to sla (to which it is quite closely linked; Falconer and Isaacson, 1962). Although strain differences may affect the blood picture in mice (Russell, Neufeld and Higgins, 1951), careful comparison between normal non-anaemic males of our partially inbred strain and the first generation hybrids with the C57B1/6 Jax strain revealed no detectable differences.The animals were maintained on Rockland rat and mouse diet, the constitution of which is shown in Table I; tap water was given ad libitum Body weights were regularly recorded to the nearest 0.1 g.Serial observations were made from the time of weaning (21-28 days) to more than 300 days of age in 64 anaemic hemizygous male mice, 45 homozygous female mice, 69 heterozygous female carriers and I I I normal male mice of the mixed strain or the hybrid mentioned above.