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A new HbA2 variant, HbA2 Victoria δ24 (B6) Gly→Asp; was identified in a patient with β-thalassemia. Family studies indicated that the mutant δ gene was trans to the gene for β-thalassemia.

The occurrence of the A?T chain (i.e. A?75 Ile? Thr) in different populations was evaluated through a study of 4250 cord blood samples and blood samples from more than 350 SS1 patients. High frequencies were observed in Italy, Yugoslavia, Turkey, Holland, but also in Japan, Vietnam, and India. The chain is (nearly) absent in the Black population of Ghana and Kenya, and low frequencies were observed in China and Australian aborigines. Only a few adult SS patients (18 out of 357) were A?T heterozygotes. The chromosomes with the A?T globin gene were mapped through an evaluation of the presence of 10 different restriction sites. The A?T chromosomes from different populations were closely related and had the same subhaplotypes of [--++?-+] (Hinc II 5' to e; Xmn I 5' to G?; Hind III in G? and A?; Hinc II in and 3' to ?ß), quite different from the subhaplotypes seen for A?T negative chromosomes.2 This suggests a common ancestor which may have originated in Southern Europe. An evaluation of the ? chain production by both chromosomes in SS patients and ß-thalassemia heterozygotes was possible for subjects with an A?T heterozygosity. It was concluded that in ß-thalassemia trait, the ? chain synthesis is directed for about two-thirds by the thalassemic chromosome and for about onethird by the normal chromosome; the contribution by the normal chromosome decreases with a decrease in total ? chain production.

The switch from γ (fetal) to β (adult) globin production was studied by the analysis of globin synthesis in chronically cannulated ovine fetuses and newborn lambs. The γ/α globin synthesis ratio decreased from 0·98 ± 0·11 (s.d.) (n= 4 samples) at 100–120 days of gestation to 0·15± 0·07 (n= 4) in lambs of 150–156 days post-conception, and the β/α synthesis ratio increased from 0·04 ± 0·06 (n= 4) to 1·13 ± 0·21 (n= 4) over the same period. In bilaterally adrenalectomized fetuses, which survived in uterountil 151–156 days, the γ/α and β/α synthesis ratios were 0·64 ± 0·14 (n= 3) and 0·25 ± 0·07 (n= 3) respectively in the 150- to 156-day period. Bilateral adrenalectomy did not affect the time of onset of β globin synthesis, but significantly decreased the rate. In one bilaterally adrenalectomized fetus the infusion of increasing concentrations of cortisol restored the rate of β globin synthesis to normal. Treatment of three intact fetuses with 100 μg cortisol/h for 3 weeks, from 100 to 121 days, did not affect the timing or rate of switch from γ to β globin synthesis. Thus fetal adrenal secretions, probably cortisol, affected the rate of change of γ to β globin synthesis but other factors must have been involved in the initiation of the switch.J. Endocr.(1985) 104, 165–170

Rats recovering from a systemic graft-vs.-host reaction (GVHR) possess factors in the serum which can inhibit the production of a local GVHR. After incubation in vitro for 1 h at 37 degrees C these factors reduce the GVH-producing potential of parental spleen or lymph node cells to 24% of control cells treated with normal serum. These factors appear within 1 wk after initiation of a systemic GVHR and some residual activity persists for up to 8 mo. The serum activity was present in the globulin fraction and was completely removed by absorption with spleen, lymph node, or kidney homogenates from either parental strain rats. These studies indicate that during the course of a systemic GVHR, serum factors directed against the host appear in the circulation and tend to inhibit the production of further GVHR by a second challenge of either parental strain cells.