- Email: [email protected]
α-THALASSAEMIA NOMENCLATURE AND ABNORMAL HAEMOGLOBINS
1024 AMNION FOR ULCERS
SIR,-The vasculogenic property of human amnion, or extraembryonic fetal membranes (discussed in your March 31 editorial), has made it an attractive dressing in venous ulceration, where several microvascular abnormalities have been described. In our controlled study2 on ulcers prepared for skin grafting by the application offresh unmodified human amnion or by a conventional method, amnion controlled infection and promoted healthy granulation tissue. Disappointingly amnion-treated ulcers, once healed, were just as likely to break down subsequently as were ulcers conventionally treated. The beneficial response to amnion may be transient, and too much should not be expected from this line of the essential difficulty in ulcer management is not the achievement of healing but the prevention of breakdown. Perhaps chorion, with its reputedly greater vasculogenic potential, will prove to be more useful than amnion in the long-term control of venous ulceration. treatment:
Departments of Surgery and Pathology,
T.
J. EGAN J. O’DRISCOLL
Regional Hospital, Limerick, Eire
ANTI-HBc TESTING IS RELIABLE FOR BLOOD DONOR SCREENING
SIR,-We agree with Dr Barbara and colleagues (Feb 11, p 346) HBsAg carriers without anti-HBc antibodies are the ones most likely to transmit HBV infection. However, donors who are HBsAg negative and anti-HBc positive (without anti-HBs antibodies) are also infectious.3,4 Concentration of such sera5 has revealed that some HBsAg was in fact present at a non-detectable level, and we that
have confirmed this. In our institution HBV contamination is prevented by routinely screening all donors for HBsAg and anti-HBcAb by ’Ausria II’ and ’Corab’ (Abbott). If anti-HBcAb is detected we test for anti-HBsAb (’Ausab’; Abbott). All blood units that are HBsAg positive and/or anti-HBc positive are discarded. For the preparation of specific immunoglobulins this donor screening strategy is better and less expensive than screening all donors for anti-HBsAb. HEPATITIS B MARKER STUDIES
would have excluded 3165 dangerous donors (598+2561+6) and only Iwould have remained undetected. Moreover we have found 6 donors who were first detected as anti-HBcAb positive alone and, in the ensuing month, found to be HBsAg positive and anti-HBcAb ,
positive. Regional Blood Transfusion Centre and Central Immunology Laboratory, Hôpital Purpan, 31052 Toulouse, France
W. SMILOVICI J. DUCOS A. MARINIERE
AMENORRHOEA, VEGETARIANISM, AND/OR LOW FAT
SIR,-The relation reported by Dr Brooks and colleagues between vegetarianism and amenorrhoea (March 10, p 559) may be explained by the fact that a vegetarian diet is low in fat, as the Colorado workers note that hormonal precursors may be affected by reduced intake of meat. We found that athletes who began their training before menarche ate significantly fewer calories, less fat, and less saturated fat than did their post-menarche-trained teammates.1 Consistent with these dietary differences the pre-menarche athletes were also leaner than their post-menarche-trained teammates. The pre-menarche athletes had menarche significantly later (15-1±0-55 vs 12 8:t0’2years) and had a higher incidence of oligoamenorrhoea, and amenorrhoea than did the post-menarche-trained a
athletes.I
Amenorrhoeic athletes have low levels of oestrogen and low to low-normal gonadotropins.2-4 Nutritional status and a vegetarian, low-fat diet can influence the production and excretion of oestrogen in women, resulting in a decreased plasma concentration of oestrogen.Leanness is associated with a decrease in the extraglandular conversion of androgen to oestrogen,and the metabolism of oestrogen to less potent forms. Although some grazing animals are infertile because of consumption of plants rich in phyto-oestrogens, as cited by Brooks et al, most cattle breed satisfactorily on herbage. Pertinent to athletes, however, are the females of a very lean breed of cattle, the Charolais or double-muscled cattle, which have troubles with puberty, fertility, and sexuality: "Les femmelles presentant 1’hypertrophie musculaire sont manifestement atteintes de troubles physiologiques concernant leur puberte, leur fertilite et leur sexualite en general". The bulls are not very fertile either. Excessive leanness8seems implicated, as for athletes and undernourished women.9, 10 Harvard Center for Population Studies, Cambridge, Massachusetts, 02138, USA
ROSÉ E. FRISCH
&agr;-THALASSAEMIA NOMENCLATURE AND ABNORMAL HAEMOGLOBINS Since January, 1979, we have tested 446 072 blood donations from 107 985 donors (table). Of the 11 donors that were "HBsAg positive only" 4 came from the same blood collection site, a prison. Prisoners, like drug addicts, are a high risk population. Among "normal" blood donors HBsAg positivity in isolation is very rare. Our results differ from those of Barbara et al who found 5 antiHBc negative donors among 114 HBsAg positive donors. Their results may be explained by lack of sensitivity of the technique they used. We believe that our strategy is the best; if one marker has to be used (for economic reasons for example) it must be anti-HBcAb.6 Since 1979, screening for HBsAg alone would have excluded only 609 dangerous donors (11+598) while screening for anti-HBcAb 1. 2.
Faulk WP, Matthews RN, Stevens PJ, Bennett JP, Burgos H, Hsi B-L. Human amnion as an adjunct in wound healing. Lancet 1980; i: 1156-58. Egan TJ, O’Driscoll J, Thakar DR. Human amnion in the management of chronic ulceration of the lower limb: a clinico-pathologic study. Angiology 1983; 34: 197-203.
3.
Hoofnagle JH, Seeff LB, Bales ZB, et al. Type B hepatitis after transfusion with blood containing antibody to hepatitis B core antigen. N Engl J Med 1978; 298: 1379-83. 4. Lander JJ, Gitnick GL, Gelb LH, et al. Anticore antibody screening of transfusion blood. Vox Sang 1978; 34: 77-80. 5. Katchaki JN, Brouwer R, Siem TH. Anti-HBc and blood infectivity. N Engl J Med 6.
1978; 298: 1422. Chataing B, Ducos J, Smilovici W, Trepo C. In- International forum. Vox Sang 1983; 44: 62-64.
SIR,-The nomenclature suggested by Professor Lehmann and Dr Carrell (March 10, p 552) has suddenly stripped the terminology for a-thalassaemia of complex ambiguities and deserves universal adoption. Clinicians and laboratory workers will welcome it. 1. Frisch
RE, von Gotz-Welbergen A, McArthur JW, et al. Delayed menarche and amenorrhea of college athletes in relation to age of onset of training. JAMA 1981; 246: 1559-63. 2. Frisch RE, von Gotz-Welbergen A, McArthur JW, et al. Annual meeting of Endocrine Society (June, 1981, Cincinnati): abstr 147. 3. Schwartz B, Cumming DC, Riordan E, Selye M, Yen SS, Rebar RW Exercise associated amenorrhea: a distinct entity? Am JObstet Gynecol 1982; 143: 859-61. 4. Dale E, Gerlach DH, Wilhite AL. Menstrual dysfunction in distance runners. Obstet
Gynecol 1979; 54: 47-53. BR, et al. Estrogen excretion patterns and plasma levels in vegetarian and omnivorous women. N Engl J Med 1982; 307: 1542-47. 6. Siiteri PK, MacDonald PC. The role of extra-glandular estrogen in human endocrinology. In: Geiger SR, Astwood EB, Greep RO, eds. Handbook of physiology. New York: American Physiological Society, 1973: 615-29. 7. Fishman J, Boyar RM, Hellmen L. Influence of body weight on estradiol metabolism in young women. J Clin Endocrinol Metab 1975; 41: 989-91. 8. Vissac B, Perreau B, Mauleon P, Menissier F. Étude du caractère culard IX: Fertilité des femelles et aptitude maternelle. Ann Génét Sélection Animale 1974; 6: 35-48. 9. Frisch RE, McArthur JW. Menstrual cycles: Fatness as a determinant of minimum weight for height necessary for their maintenance or onset. Science 1974; 185: 5. Goldin
949-51. 10.
Vigersky RA, Andersen AE, Thompson RH, Loriaux DL. Hypothalamic dysfunction in secondary amenorrhea associated with simple weight loss. N Engl J Med 1977, 297: 1141-45.
1025 Ever since van Enk et al’ described fifteen pregnancies with 13 live births in two Ghanaian adults with sickle cell anaemia (SS) and suggested that the benign obstetric history could be due to the proven associated a-thalassaemia, the high incidence of this gene in West Africans and people of their descent across the Atlantic has been widely acknowledged. While recently investigating a Ghanaian adult with periodic idiopathic intravascular haemolysis I received this report: "The patient has a-thalassaemia type 1 equivalent to African homozygous a-thalassaemia type 2, with G-6-PD total deficiency." Following Lehmann and Carrell the thalassaemia diagnosis would be "2a-thalassaemia(trans)", indicating at a glance how many genes were involved. In West Africa where qualitative and quantitative defects in haemoglobin formation abound (1 in 3 healthy adults carry the trait 2) interaction of a-thalassaemia with 0-chain mutants will be frequent. Such interaction reduces the amount of abnormal haemoglobin in the trait and was indeed part of the reasoning behind Lehmann and Carrell’s hypothesis (now proven) of the duplication of the a-globin gene in some communities.33 Quantifying the proportion of abnormal haemoglobin i’n the common haemoglobin traits is therefore helpful in unmasking concomitant a-thalassaemia. For instance, in 82 consecutive cases of sickle cell trait that I have counselled in the past 24 months here in London 36 (44%) had just one-quarter of the total haemoglobin as sickle haemoglobin (mean 25%, range 20-28%). Some of these had haemoglobin H inclusion bodies in the erythrocytes, with reduced haemoglobin A2 - Wells and Itanowere the first to demonstrate that the proportion of sickle haemoglobin (S) in a group of unselected subjects with sickle cell trait (heterozygote AS) could be as low as 25%, and family studies of this ratio suggested that it was under genetic control.5 The three known peaks of haemoglobin S proportion in the West African sickle cell trait are around 25%, around 30%, and around 38%. The different a-thalassaemia carrier states are very difficult to identify by haematological or haemobut if one had the resources for restriction globin endonuclease analysis would it be considered merely academic to try to demonstrate (as Brittenham et al did for Indian sickle cell trait 7) whether the 25% S sickle cell trait phenotype from West Africa was invariably associated with Lehmann and Carrell’s 2a-thalassaemia, the 30% S sickle cell trait phenotype with their 1 a-thalassaemia, and the 38% sickle cell trait phenotype with no a-thalassaemia genes at all?
analysis,
BUPA Medical Centre, Webb House,
King’s Cross, London N1 9TA
relative to the numbers of cycling cells initially added to the cultures.l,2 Variations in the BrdU/cell ratio can alter SCE frequencies by a factor of nearly two. 1,2 Palmer and co-workers used 0 - 5 ml of blood with a BrdU final concentration of 30 mol/1. They provide no information about the number of lymphocytes in the 0 - 5 ml sample. Since many disease states can alter lymphocyte responses to mitogens such as phytohaemagglutinin and since chlorambucil lowers peripheral lymphocyte counts, it is possible that in preparations from Behcet’s patients (treated and untreated) the BrdU/cycling-lymphocyte ratio was higher than that in the controls. This could account for most if not all of the observed increase in SCE frequency. Such difficulties in interpretation can be reduced by making preliminary lymphocyte counts and then standardising the number of lymphocytes in each culture.2,3This does not eliminate problems associated with differential lymphocyte response to mitogens, but it does at least represent an attempt to avoid misinterpretations of data. In view of the increasing enthusiasm for the use of SCE counts to indicate environmental chromosome damage and to assess effects of medical treatments, critical attention must be given to the details of the methods used. The report of Palmer et al and your editorial raise other issues. The editorial alluded to the transience of the SCE "phenomenon" following acute exposure to mutagenic agents as a limitation of the procedure, thus reiterating the original conclusion of Stetka and Wolff.4 It did not, however, refer to a later study which demonstrated that long-lived increases in SCE frequency (>5 months) were by repeated exposures to low doses of mitomycin-C. This study revealed the cumulative effects of multiple exposures and also the appearance of a subpopulation of lymphocytes with greatly increased SCE frequencies, cells subsequently referred to as "high frequency cells" or HFCs.3 We agree with Palmer et al that monitoring of SCEs during chemotherapy may indicate patients’ individual susceptibility to chromosome damage. HFCs might represent an unusually repairdeficient and/or drug-resistant clone of cells in which genetic damage due to drug exposure has accumulated. If so, then SCE analysis would be not only useful but also perhaps critical in determining a patient’s drug regimen, as the appearance of HFCs might indicate increased risk of secondary neoplasia.
induced
Division of Human Genetics, State University of New York and Children’s Hospital, Buffalo, NY 14222, USA
at
Buffalo
R. M. BANNERMAN D. G. STETKA
F. I. D. KONOTEY-AHULU
SISTER CHROMATID EXCHANGE LYMPHOCYTES
FREQUENCIES
TREATMENT OF HAIRY-CELL LEUKAEMIA WITH RECOMBINANT HUMAN &agr;2-INTERFERON
IN
SiR,—Dr Palmer and colleagues (Feb 4, p 246) describe apparent increases in sister chromatid exchange (SCE) frequencies in
peripheral blood lymphocytes of untreated patients with Behçet’s syndrome, and greater apparent increases following treatment with chlorambucil. These findings are of great interest, as emphasised in the accompanying editorial. However, interpretation of these results may be clouded by a possible technical artifact. Observed SCE frequencies are partly dependent upon the amount of bromodeoxyuridine (BrdU) present in the growth medium, 1. van Enk KA, Lang A, White JM, Lehmann H Benign obstetric history in women with sickle cell anaemia associated with &agr;-thalassaemia Br Med J 1972; iv: 524-26. 2 Konotey-Ahulu FID, Rmgelhann B. Sickle cell anaemia, sickle cell thalassaemia, sickle cell haemoglobin C disease and asymptomatic haemoglobin C thalassaemia in one Ghanaian family. Br Med J 1969; i: 607-12. 3. Lehmann H, Carrell RW. Differences between &agr;- and &bgr;-thalassaemia: possible duplication of the &agr;-chain gene. Br Med J 1968, iv 748-50. 4. Wells IC, Itano HA. Ratio of sickle-cell anemia hemoglobin to normal hemoglobin in sicklemics. J Biol Chem 1951; 188: 65-74 5. Neel JV, Wells IC, Itano HA. Familial differences in the proportion of abnormal hemoglobin present in the sickle cell trait. JClin Invest 1951; 30: 1120-24 6 Weatherall DJ. The diagnostic features of the different forms of thalassaemia. In. Weatherall DJ, ed. The thalassaemias Edinburgh: Churchill Livingstone. 1983: 1-26 7. Brittenham G, LozoffB, Harris JW, Kan JW, Dowy AM, Nayudu NVS. Alpha globin gene number population and restriction endonuclease studies Blood 1980, 55: 706-08
SiR,-Partly purified leucocyte a-interferon has been reported to be successful for induction of remission in hairy-cell leukaemia.6 We describe here a patient with hairy-cell leukaemia who achieved a complete remission after treatment with recombinant human a2-interferon (rHuIFN-a). In November, 1982, a 52-year-old man was referred because of pancytopenia and splenomegaly. His white-blood-cell count (WCC) 1-4x10/1 with 70% lymphocytes, positive for acid was phosphatase and tartrate. In December splenectomy was done, after which his WCC rose to 7 - 9 x 109/1 still with 72% lymphocytes. The platelet count rose from 44 to 288x 109/l. The histology of the 1. 2
Stetka DG, Carrano AV. The interaction of Hoechst 33258 and Brd U substituted DNA in the formation of sister chromatid exchanges Chromosoma 1977; 36: 21-31. Carrano AV, Minkler JL, Stetka DG, Moore DH II. Variation in the baseline sister chromatid exchange frequency in human lymphocytes Environ Mut 1980; 2:
325-37 3 Carrano AV, Moore DH. The rationale and
methodology for quantifying sister chromatid exchange in humans. In: Heddle J, ed. Mutagenicity: New horizons in genetic toxicology. New York. Academic Press, 1982. 4. Stetka DG, Wolff S. Sister chromatid exchange as an assay for genetic damage induced by mutagenic-carcinogens I. In vivo test for compounds requiring metabolic activation Mutat Res 1976; 41: 333-42. 5 Stetka DG, Minkler J, Carrano AV Induction of long-lived chromosome damage, as manifested by sister chromatid exchange, in lymphocytes of animals exposed to mitomycin C. Mutat Res 1978; 51: 383-96 6. Quesada JR, Reuben J, Hanning JT, Hersh EM, Gutterman JU. Alpha interferon for induction of remission in hairy-cell leukaemia. N Eng J Med 1984, 310: 15-18.
SIR,-The vasculogenic property of human amnion, or extraembryonic fetal membranes (discussed in your March 31 editorial), has made it an attractive dressing in venous ulceration, where several microvascular abnormalities have been described. In our controlled study2 on ulcers prepared for skin grafting by the application offresh unmodified human amnion or by a conventional method, amnion controlled infection and promoted healthy granulation tissue. Disappointingly amnion-treated ulcers, once healed, were just as likely to break down subsequently as were ulcers conventionally treated. The beneficial response to amnion may be transient, and too much should not be expected from this line of the essential difficulty in ulcer management is not the achievement of healing but the prevention of breakdown. Perhaps chorion, with its reputedly greater vasculogenic potential, will prove to be more useful than amnion in the long-term control of venous ulceration. treatment:
Departments of Surgery and Pathology,
T.
J. EGAN J. O’DRISCOLL
Regional Hospital, Limerick, Eire
ANTI-HBc TESTING IS RELIABLE FOR BLOOD DONOR SCREENING
SIR,-We agree with Dr Barbara and colleagues (Feb 11, p 346) HBsAg carriers without anti-HBc antibodies are the ones most likely to transmit HBV infection. However, donors who are HBsAg negative and anti-HBc positive (without anti-HBs antibodies) are also infectious.3,4 Concentration of such sera5 has revealed that some HBsAg was in fact present at a non-detectable level, and we that
have confirmed this. In our institution HBV contamination is prevented by routinely screening all donors for HBsAg and anti-HBcAb by ’Ausria II’ and ’Corab’ (Abbott). If anti-HBcAb is detected we test for anti-HBsAb (’Ausab’; Abbott). All blood units that are HBsAg positive and/or anti-HBc positive are discarded. For the preparation of specific immunoglobulins this donor screening strategy is better and less expensive than screening all donors for anti-HBsAb. HEPATITIS B MARKER STUDIES
would have excluded 3165 dangerous donors (598+2561+6) and only Iwould have remained undetected. Moreover we have found 6 donors who were first detected as anti-HBcAb positive alone and, in the ensuing month, found to be HBsAg positive and anti-HBcAb ,
positive. Regional Blood Transfusion Centre and Central Immunology Laboratory, Hôpital Purpan, 31052 Toulouse, France
W. SMILOVICI J. DUCOS A. MARINIERE
AMENORRHOEA, VEGETARIANISM, AND/OR LOW FAT
SIR,-The relation reported by Dr Brooks and colleagues between vegetarianism and amenorrhoea (March 10, p 559) may be explained by the fact that a vegetarian diet is low in fat, as the Colorado workers note that hormonal precursors may be affected by reduced intake of meat. We found that athletes who began their training before menarche ate significantly fewer calories, less fat, and less saturated fat than did their post-menarche-trained teammates.1 Consistent with these dietary differences the pre-menarche athletes were also leaner than their post-menarche-trained teammates. The pre-menarche athletes had menarche significantly later (15-1±0-55 vs 12 8:t0’2years) and had a higher incidence of oligoamenorrhoea, and amenorrhoea than did the post-menarche-trained a
athletes.I
Amenorrhoeic athletes have low levels of oestrogen and low to low-normal gonadotropins.2-4 Nutritional status and a vegetarian, low-fat diet can influence the production and excretion of oestrogen in women, resulting in a decreased plasma concentration of oestrogen.Leanness is associated with a decrease in the extraglandular conversion of androgen to oestrogen,and the metabolism of oestrogen to less potent forms. Although some grazing animals are infertile because of consumption of plants rich in phyto-oestrogens, as cited by Brooks et al, most cattle breed satisfactorily on herbage. Pertinent to athletes, however, are the females of a very lean breed of cattle, the Charolais or double-muscled cattle, which have troubles with puberty, fertility, and sexuality: "Les femmelles presentant 1’hypertrophie musculaire sont manifestement atteintes de troubles physiologiques concernant leur puberte, leur fertilite et leur sexualite en general". The bulls are not very fertile either. Excessive leanness8seems implicated, as for athletes and undernourished women.9, 10 Harvard Center for Population Studies, Cambridge, Massachusetts, 02138, USA
ROSÉ E. FRISCH
&agr;-THALASSAEMIA NOMENCLATURE AND ABNORMAL HAEMOGLOBINS Since January, 1979, we have tested 446 072 blood donations from 107 985 donors (table). Of the 11 donors that were "HBsAg positive only" 4 came from the same blood collection site, a prison. Prisoners, like drug addicts, are a high risk population. Among "normal" blood donors HBsAg positivity in isolation is very rare. Our results differ from those of Barbara et al who found 5 antiHBc negative donors among 114 HBsAg positive donors. Their results may be explained by lack of sensitivity of the technique they used. We believe that our strategy is the best; if one marker has to be used (for economic reasons for example) it must be anti-HBcAb.6 Since 1979, screening for HBsAg alone would have excluded only 609 dangerous donors (11+598) while screening for anti-HBcAb 1. 2.
Faulk WP, Matthews RN, Stevens PJ, Bennett JP, Burgos H, Hsi B-L. Human amnion as an adjunct in wound healing. Lancet 1980; i: 1156-58. Egan TJ, O’Driscoll J, Thakar DR. Human amnion in the management of chronic ulceration of the lower limb: a clinico-pathologic study. Angiology 1983; 34: 197-203.
3.
Hoofnagle JH, Seeff LB, Bales ZB, et al. Type B hepatitis after transfusion with blood containing antibody to hepatitis B core antigen. N Engl J Med 1978; 298: 1379-83. 4. Lander JJ, Gitnick GL, Gelb LH, et al. Anticore antibody screening of transfusion blood. Vox Sang 1978; 34: 77-80. 5. Katchaki JN, Brouwer R, Siem TH. Anti-HBc and blood infectivity. N Engl J Med 6.
1978; 298: 1422. Chataing B, Ducos J, Smilovici W, Trepo C. In- International forum. Vox Sang 1983; 44: 62-64.
SIR,-The nomenclature suggested by Professor Lehmann and Dr Carrell (March 10, p 552) has suddenly stripped the terminology for a-thalassaemia of complex ambiguities and deserves universal adoption. Clinicians and laboratory workers will welcome it. 1. Frisch
RE, von Gotz-Welbergen A, McArthur JW, et al. Delayed menarche and amenorrhea of college athletes in relation to age of onset of training. JAMA 1981; 246: 1559-63. 2. Frisch RE, von Gotz-Welbergen A, McArthur JW, et al. Annual meeting of Endocrine Society (June, 1981, Cincinnati): abstr 147. 3. Schwartz B, Cumming DC, Riordan E, Selye M, Yen SS, Rebar RW Exercise associated amenorrhea: a distinct entity? Am JObstet Gynecol 1982; 143: 859-61. 4. Dale E, Gerlach DH, Wilhite AL. Menstrual dysfunction in distance runners. Obstet
Gynecol 1979; 54: 47-53. BR, et al. Estrogen excretion patterns and plasma levels in vegetarian and omnivorous women. N Engl J Med 1982; 307: 1542-47. 6. Siiteri PK, MacDonald PC. The role of extra-glandular estrogen in human endocrinology. In: Geiger SR, Astwood EB, Greep RO, eds. Handbook of physiology. New York: American Physiological Society, 1973: 615-29. 7. Fishman J, Boyar RM, Hellmen L. Influence of body weight on estradiol metabolism in young women. J Clin Endocrinol Metab 1975; 41: 989-91. 8. Vissac B, Perreau B, Mauleon P, Menissier F. Étude du caractère culard IX: Fertilité des femelles et aptitude maternelle. Ann Génét Sélection Animale 1974; 6: 35-48. 9. Frisch RE, McArthur JW. Menstrual cycles: Fatness as a determinant of minimum weight for height necessary for their maintenance or onset. Science 1974; 185: 5. Goldin
949-51. 10.
Vigersky RA, Andersen AE, Thompson RH, Loriaux DL. Hypothalamic dysfunction in secondary amenorrhea associated with simple weight loss. N Engl J Med 1977, 297: 1141-45.
1025 Ever since van Enk et al’ described fifteen pregnancies with 13 live births in two Ghanaian adults with sickle cell anaemia (SS) and suggested that the benign obstetric history could be due to the proven associated a-thalassaemia, the high incidence of this gene in West Africans and people of their descent across the Atlantic has been widely acknowledged. While recently investigating a Ghanaian adult with periodic idiopathic intravascular haemolysis I received this report: "The patient has a-thalassaemia type 1 equivalent to African homozygous a-thalassaemia type 2, with G-6-PD total deficiency." Following Lehmann and Carrell the thalassaemia diagnosis would be "2a-thalassaemia(trans)", indicating at a glance how many genes were involved. In West Africa where qualitative and quantitative defects in haemoglobin formation abound (1 in 3 healthy adults carry the trait 2) interaction of a-thalassaemia with 0-chain mutants will be frequent. Such interaction reduces the amount of abnormal haemoglobin in the trait and was indeed part of the reasoning behind Lehmann and Carrell’s hypothesis (now proven) of the duplication of the a-globin gene in some communities.33 Quantifying the proportion of abnormal haemoglobin i’n the common haemoglobin traits is therefore helpful in unmasking concomitant a-thalassaemia. For instance, in 82 consecutive cases of sickle cell trait that I have counselled in the past 24 months here in London 36 (44%) had just one-quarter of the total haemoglobin as sickle haemoglobin (mean 25%, range 20-28%). Some of these had haemoglobin H inclusion bodies in the erythrocytes, with reduced haemoglobin A2 - Wells and Itanowere the first to demonstrate that the proportion of sickle haemoglobin (S) in a group of unselected subjects with sickle cell trait (heterozygote AS) could be as low as 25%, and family studies of this ratio suggested that it was under genetic control.5 The three known peaks of haemoglobin S proportion in the West African sickle cell trait are around 25%, around 30%, and around 38%. The different a-thalassaemia carrier states are very difficult to identify by haematological or haemobut if one had the resources for restriction globin endonuclease analysis would it be considered merely academic to try to demonstrate (as Brittenham et al did for Indian sickle cell trait 7) whether the 25% S sickle cell trait phenotype from West Africa was invariably associated with Lehmann and Carrell’s 2a-thalassaemia, the 30% S sickle cell trait phenotype with their 1 a-thalassaemia, and the 38% sickle cell trait phenotype with no a-thalassaemia genes at all?
analysis,
BUPA Medical Centre, Webb House,
King’s Cross, London N1 9TA
relative to the numbers of cycling cells initially added to the cultures.l,2 Variations in the BrdU/cell ratio can alter SCE frequencies by a factor of nearly two. 1,2 Palmer and co-workers used 0 - 5 ml of blood with a BrdU final concentration of 30 mol/1. They provide no information about the number of lymphocytes in the 0 - 5 ml sample. Since many disease states can alter lymphocyte responses to mitogens such as phytohaemagglutinin and since chlorambucil lowers peripheral lymphocyte counts, it is possible that in preparations from Behcet’s patients (treated and untreated) the BrdU/cycling-lymphocyte ratio was higher than that in the controls. This could account for most if not all of the observed increase in SCE frequency. Such difficulties in interpretation can be reduced by making preliminary lymphocyte counts and then standardising the number of lymphocytes in each culture.2,3This does not eliminate problems associated with differential lymphocyte response to mitogens, but it does at least represent an attempt to avoid misinterpretations of data. In view of the increasing enthusiasm for the use of SCE counts to indicate environmental chromosome damage and to assess effects of medical treatments, critical attention must be given to the details of the methods used. The report of Palmer et al and your editorial raise other issues. The editorial alluded to the transience of the SCE "phenomenon" following acute exposure to mutagenic agents as a limitation of the procedure, thus reiterating the original conclusion of Stetka and Wolff.4 It did not, however, refer to a later study which demonstrated that long-lived increases in SCE frequency (>5 months) were by repeated exposures to low doses of mitomycin-C. This study revealed the cumulative effects of multiple exposures and also the appearance of a subpopulation of lymphocytes with greatly increased SCE frequencies, cells subsequently referred to as "high frequency cells" or HFCs.3 We agree with Palmer et al that monitoring of SCEs during chemotherapy may indicate patients’ individual susceptibility to chromosome damage. HFCs might represent an unusually repairdeficient and/or drug-resistant clone of cells in which genetic damage due to drug exposure has accumulated. If so, then SCE analysis would be not only useful but also perhaps critical in determining a patient’s drug regimen, as the appearance of HFCs might indicate increased risk of secondary neoplasia.
induced
Division of Human Genetics, State University of New York and Children’s Hospital, Buffalo, NY 14222, USA
at
Buffalo
R. M. BANNERMAN D. G. STETKA
F. I. D. KONOTEY-AHULU
SISTER CHROMATID EXCHANGE LYMPHOCYTES
FREQUENCIES
TREATMENT OF HAIRY-CELL LEUKAEMIA WITH RECOMBINANT HUMAN &agr;2-INTERFERON
IN
SiR,—Dr Palmer and colleagues (Feb 4, p 246) describe apparent increases in sister chromatid exchange (SCE) frequencies in
peripheral blood lymphocytes of untreated patients with Behçet’s syndrome, and greater apparent increases following treatment with chlorambucil. These findings are of great interest, as emphasised in the accompanying editorial. However, interpretation of these results may be clouded by a possible technical artifact. Observed SCE frequencies are partly dependent upon the amount of bromodeoxyuridine (BrdU) present in the growth medium, 1. van Enk KA, Lang A, White JM, Lehmann H Benign obstetric history in women with sickle cell anaemia associated with &agr;-thalassaemia Br Med J 1972; iv: 524-26. 2 Konotey-Ahulu FID, Rmgelhann B. Sickle cell anaemia, sickle cell thalassaemia, sickle cell haemoglobin C disease and asymptomatic haemoglobin C thalassaemia in one Ghanaian family. Br Med J 1969; i: 607-12. 3. Lehmann H, Carrell RW. Differences between &agr;- and &bgr;-thalassaemia: possible duplication of the &agr;-chain gene. Br Med J 1968, iv 748-50. 4. Wells IC, Itano HA. Ratio of sickle-cell anemia hemoglobin to normal hemoglobin in sicklemics. J Biol Chem 1951; 188: 65-74 5. Neel JV, Wells IC, Itano HA. Familial differences in the proportion of abnormal hemoglobin present in the sickle cell trait. JClin Invest 1951; 30: 1120-24 6 Weatherall DJ. The diagnostic features of the different forms of thalassaemia. In. Weatherall DJ, ed. The thalassaemias Edinburgh: Churchill Livingstone. 1983: 1-26 7. Brittenham G, LozoffB, Harris JW, Kan JW, Dowy AM, Nayudu NVS. Alpha globin gene number population and restriction endonuclease studies Blood 1980, 55: 706-08
SiR,-Partly purified leucocyte a-interferon has been reported to be successful for induction of remission in hairy-cell leukaemia.6 We describe here a patient with hairy-cell leukaemia who achieved a complete remission after treatment with recombinant human a2-interferon (rHuIFN-a). In November, 1982, a 52-year-old man was referred because of pancytopenia and splenomegaly. His white-blood-cell count (WCC) 1-4x10/1 with 70% lymphocytes, positive for acid was phosphatase and tartrate. In December splenectomy was done, after which his WCC rose to 7 - 9 x 109/1 still with 72% lymphocytes. The platelet count rose from 44 to 288x 109/l. The histology of the 1. 2
Stetka DG, Carrano AV. The interaction of Hoechst 33258 and Brd U substituted DNA in the formation of sister chromatid exchanges Chromosoma 1977; 36: 21-31. Carrano AV, Minkler JL, Stetka DG, Moore DH II. Variation in the baseline sister chromatid exchange frequency in human lymphocytes Environ Mut 1980; 2:
325-37 3 Carrano AV, Moore DH. The rationale and
methodology for quantifying sister chromatid exchange in humans. In: Heddle J, ed. Mutagenicity: New horizons in genetic toxicology. New York. Academic Press, 1982. 4. Stetka DG, Wolff S. Sister chromatid exchange as an assay for genetic damage induced by mutagenic-carcinogens I. In vivo test for compounds requiring metabolic activation Mutat Res 1976; 41: 333-42. 5 Stetka DG, Minkler J, Carrano AV Induction of long-lived chromosome damage, as manifested by sister chromatid exchange, in lymphocytes of animals exposed to mitomycin C. Mutat Res 1978; 51: 383-96 6. Quesada JR, Reuben J, Hanning JT, Hersh EM, Gutterman JU. Alpha interferon for induction of remission in hairy-cell leukaemia. N Eng J Med 1984, 310: 15-18.