α THALASSAEMIA IN PAPUA NEW GUINEA

424 2.

Köberling J,

Tattersall R, eds. The genetics of diabetes. London: Academic Press,

1982. 3. Burnet FM. The clonal selection theory of acquired immunity. Cambridge: Cambridge University Press, 1959. 4. Adams DD, Knight JG. The H gene theory of inherited autoimmune disease. Lancet 1980; i: 396-98. 5. Bottazzo GF, Florin-Christensen A, Doniach D. Islet-cell antibodies in diabetes mellitus with autoimmune polyendocrine deficiencies. Lancet 1974; ii: 1279-83. 6. Irvine WJ, Gray RS, McCallum CJ. Pancreatic islet cell antibody as a marker for asymptomatic and latent diabetes and prediabetes. Lancet 1976; ii: 1097-1102. 7. Lendrum R, Walker G, Cudworth AG, et al. Islet-cell antibodies in diabetes mellitus. Lancet 1976; ii: 1273-76. 8. Nerup J, Anderson OO, Bendixen G, et al. Antipancreatic cellular hypersensitivity in diabetes mellitus. Diabetes 1971; 20: 424-27.

Preliminary Communication &agr;

THALASSAEMIA IN PAPUA NEW GUINEA

STEPHEN J. OPPENHEIMER D. R. HIGGS D. J. WEATHERALL JANE BARKER R. A. SPARK

Department of Tropical Paediatrics, Liverpool School of Tropical Medicine; Papua New Guinea Institute for Medical Research, Goroka, Eastern Highlands Province, Papua New Guinea; and Medical Research Council Molecular Haematology Unit, Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford

9. Adams DD. Thyroid-stimulating autoantibodies. Vitamin Horm 1980; 38: 119-203. 10. Adams DD. Autoimmune mechanisms. In: Davies TF, ed. Autoimmune endocrine disease. New York: Wiley, 1983: 1-39. 11. Lindstrom JM, Seybold ME, Lennon VA, et al. Antibody to acetylcholine receptor in myasthenia gravis. Neurology 1976; 26: 1054-59. 12. Jerne NK. The natural selection theory of antibody formation. Proc Natl Acad Sci USA 1955; 41: 849-53. 13. Weigert MG, Cesari IM, Yonkovich SJ, Cohn M. Variability in the lambda light chain sequences of mouse antibody. Nature 1970; 228: 1045-47. 14. Bernard O, Hozumi N, Tonegawa S. Sequences of mouse immunoglobulin light chain genes before and after somatic changes. Cell 1978; 15: 1133-44. 15. Gearhart PJ, Bogenhagen DF. Clusters of point mutations are found exclusively around rearranged antibody variable genes. Proc Natl Acad Sci USA 1983; 80: 3439-43. 16. Pyke DA, Nelson PG. Diabetes in identical twins. In: Creutzfeldt W, Kobberling J, Neel JV, eds. The genetics of diabetes mellitus. Berlin: Springer-Verlag, 1976: 194-202. 17. Gamble DR, Kinsley ML, Fitzgerald MG, et al. Viral antibodies in diabetes mellitus. Br Med J 1969; iii: 627-30. 18. Simpson NE. Multifactorial inheritance. A possible hypothesis for diabetes. Diabetes 1964; 13: 462-71. 19. Knight JG, Adams DD. The genetic basis of autoimmune disease. Ciba Foundn Symp 1982; 90: 35-56. 20. Benacerraf B, McDevitt HO. The histocompatibility-linked immune response genes. Science 1972; 175: 273-79. 21. Jerne NK. Towards a network theory of the immune system. Ann Inst Pasteur 1974; 125C: 373-89. 22. Loghem E van. Genetic studies of human immunoglobulins. In: Weir DM, ed. Handbook of experimental immunology, 3rd ed. Oxford: Blackwell, 1978: 11.1-11.6. 23. Adams DD, Adams YJ, Knight JG, et al. On the nature of the genes influencing the prevalence of Graves’ disease. Life Sci 1983; 31: 3-13. 24. Hodge SE, Anderson CE, Neiswanger K, et al. Close genetic linkage between diabetes mellitus and Kidd blood group. Lancet 1981; ii: 893-95. 25. McBride OW, Hieter PA, Hollis GF, et al. Chromosomal location of human x and &lgr; immunoglobulin light chain constant region genes. J Exp Med 1982; 155: 1480-90.

SEVERAL surveys have suggested that inherited red-cell disorders are common in Melanesia. t-3 As part of a study of anaemia in Madang on the north coast of Papua New Guinea, the haemoglobin constitution of 217 newborn infants was

26. Adams DD. The V gene theory of inherited autoimmune disease. J Clin Lab Immunol

analysed.

1978; 1: 17-24. 27.

Zakarija M. Immunochemical characterization of thyroid-stimulating antibody (TSAb) of Graves’ disease: evidence for restricted heterogeneity. J Clin Immunol 1983; 10: 77-85.

Knight JG, Adams DD. Genes determining autoimmune disease in New Zealand mice. J Clin Lab Immunol 1981; 5: 165-70. In vitro correlate for a clonal deletion mechanism of immune 29. Ishii N, Nagy ZA, Klein J. response gene controlled non-responsiveness. J Exp Med 1983; 157: 998-1005. 30. Mullbacher A. Neonatal tolerance induction to alloantigens alters major histocompatibility complex-restricted response patterns. Proc Natl Acad Sci USA 1981; 28.

78: 7689-91. 31. Mullbacher A, Blanden RV, Brenan M. Neonatal tolerance of

major histocompatibility complex antigens alters Ir gene control of the cytotoxic T cell response to vaccinia virus. J Exp Med 1983; 157: 1324-38. 32. Arakian H, Welsh J, Ebringer A, Entwistle CC. Ankylosing spondylitis, HLA-B27 and klebsiella. II. Cross-reactivity studies with human tissue typing sera. Br J Exp 33.

Pathol 1980; 60: 92-96. Zinkernagel RM, Doherty PC. Restriction of in vitro T cell-mediated cytotoxicity in lymphocytic choriomeningitis within a syngeneic or semiallogeneic system. Nature

1974; 248: 701-02. 34. Shevach EM, Paul WE, Green I. Histocompatibility linked immune response gene function in guinea pigs. J Exp Med 1972; 136: 1207-21. 35. Cudworth AG, Woodrow JC. Evidence for HLA-linked genes in juvenile diabetes mellitus. Br Med J 1975; iii: 133-35. 36. Vague PH, Melis C, Mercier P, et al. The increased frequency of the Lewis negative blood group in a diabetic population. Diabetologia 1978; 15: 33-36. 37. Raum D, Alper CA, Stein R, Gabbay KH. Genetic marker for insulin-dependent diabetes mellitus. Lancet 1979; i: 1208-10. 38. McCluskey J, McCann VJ, Hay PH, et al. HLA and complement allotypes in type 1 (insulin-dependent) diabetes. Diabetologia 1983; 24: 162-65. 39. Barbosa J, Bach FM, Rich SS. Genetic heterogeneity of diabetes and HLA. Clin Genet 1982; 21: 25-32. 40. Johnston C, Pyke DA, Cudworth AG, Wolf E. HLA-DR typing in identical twins with insulin-dependent diabetes: differences between concordant and discordant pairs. Br Med J 1983; 286: 253-55. 41. Mastsumoto H, Nakao Y, Miyazaki T, et al. IgG heavy chain allotypes (Gm) in autoimmune disorders. In: Dawkins RL, Christiansen FT, Zilko PJ, eds. Immunogenetics in rheumatology, Oxford: Excerpta Medica, 1982: 38-42. 42. Whittingham S, Matthews JD, Schanfield MS, et al. Effect of gene interaction on susceptibility to disease. Tissue Antigens 1981; 17: 252-54. 43. Craighead JE. Current views on the etiology of insulin-dependent diabetes mellitus. N

Engl J Med 1978; 299: 1439-45.

Haemoglobin Bart’s was detected in cord blood samples from 81% of 217 infants born in Madang on the north coast of Papua New Guinea. Analysis of the &agr; globin genes of 30 infants and adults from the same region showed that all but 3 were heterozygous or homozygous for the deletion form of &agr;+thalassaemia. None of 18 cord blood samples from infants born in Goroka in the Eastern Highlands Province had haemoglobin Bart’s, and in each case the &agr; globin genes were normal. Preliminary geographical and linguistic analyses of both groups suggest that the prevalence of a thalassaemia may be related to altitude rather than to linguistic grouping and hence that resistance to malaria may be at least one reason why &agr; thalassaemia is so common in some populations. Summary

INTRODUCTION

PATIENTS AND METHODS

Cord blood samples were collected from 217 infants born at Madang Provincial Hospital and from 18 born at Goroka Base Hospital in the Eastern Highlands Province (see accompanying figure). The red cells were washed three times and stored at - 45’C. Haemoglobin analysis by starch-gel electrophoresis, pH 8’6, and estimation of the relative amount of haemoglobin Bart’s by quantitative cellulose-acetate electrophoresis, pH 8 -9, were carried out by standard methods.3 The a globin genes were studied in the cord blood samples of the 18 infants born in Goroka, cord blood samples of 21 infants born in Madang, and blood samples from 9 adults in Madang. Preparation of DNA from buffy coats and analysis of the a globin genes after digestion with Bam Hl and hybridisation with an a-globin-specific probe were carried out as previously described.4,s RESULTS

Of the 217 infants born in Madang Hospital, 175 (81 %) had detectable haemoglobin Bart’s, with levels ranging from 0-8% to 11-0%. None of the 18 infants born in Goroka Hospital had detectable haemoglobin Bart’s. 2 Highlands infants born in Madang had no haemoglobin Bart’s. A subset of 183 results based on the language spoken6 and area of origin of the parents is shown in the table. In the three lowland Papuan linguistic groups (groups 1-3) the combined frequency of detectable haemoglobin Bart’s was 93% (103/111) and in the foothill ethnic groups (groups 4 and 5) the frequency was 47% (7/15), whereas none of the 20 ethnic Highlands infants had detectable haemoglobin Bart’s.

425

Papua New Guinea, showing distribution of major linguistic groups forming basis of this study.

To determine whether a high level of haemoglobin Bart’s at birth reflects the presence ofa thalassaemia in this population and to provide further information about the prevalence of a thalassaemia in these groups, a gene mapping was carried out on 48 samples. All the 18 samples from Highlands infants showed a normal a globin genotype (aalaa). Of the 30 samples from infants and adults from the Madang provinceh3 showed a normal a genotype, but the remainder were either heterozygous (-alaa) or homozygous (-al-a) for the deletion form of a thalassaemia. Of the 39 a thalassaemia chromosomes, 27 were of the - a 4-2 type, 10 were of the a3’type, and 2 were unclassified - a. We compared the a globin genotype with the level of haemoglobin Bart’s at birth in 31 infants; 20 infants with normal a globin genes (aalaa) had no haemoglobin Bart’s and 1 had 1’ 4% haemoglobin Bart’s; 4 0 thalassaemia heterozygotes (-alaa) had 0%,+ 2-1%, 2-3%, and 2 - 4% haemoglobin Bart’s; and 6 a thalassaemia homozygotes had haemoglobin Bart’s levels ranging from 4 - 7% to 8 - 2%. -

,

FREQUENCY OF HAEMOGLOBIN

(Hb) BART’S AT BIRTH IN THE

DIFFERENT LINGUISTIC GROUPS STUDIED

DISCUSSION

This

pilot study has shown that an extremely high proportion of newborn infants from the north New Guinea coastal lowland region have haemoglobin Bart’s. Globin gene

mapping analysis has confirmed that detectable haemoglobin Bart’s at birth is caused by the deletion form of a+ thalassaemia in this population. The apparent rarity of the more severe clinical phenotypes of a thalassaemia, the haemoglobin Bart’s hydrops syndrome and haemoglobin H disease, presumably reflects the rarity of aO thalassaemia determinants (ie, conditions in which both a globin genes are deleted on the same chromosome4) in this region. The deletion forms of a thalassaemia are distributed widely throughout Africa, the Mediterranean, the Middle East, the Indian subcontinent, and South-East Asia.4 The prevalence varies from 1-2% to 80%. The prevalence of 95% in the Madang/Adelbert linguistic group in our study is the highest yet reported. It seems likely that the deletion forms of a thalassaemia result from unequal crossing-over between homologous pairs of chromosomes 16, leaving one a gene on one of the pair and three on the other. However, in every population examined to date the single a globin gene chromosome is much commoner than the triplicated a gene arrangement. Hence, it seems likely that under certain circumstances the single a gene chromosome has come under strong selection. Although the selective factors that have maintained the high prevalence of the deletion forms of a thalassaemia are not known, their geographical distribution suggests that resistance to Plasmodium falciparum malaria may have had a role. Although the numbers of cases we studied are small, a thalassaemia is unevenly distributed among the population and the prevalence appears to be related to the altitude of residence of the various groups examined. Lowlands New Guinea has endemic malaria, ranging from hyperendemic to holoendemic, which was present before European contact.9 Highlands New Guinea, in contrast, had no malaria transmission over 2000 m and only seasonal Plasmodium vivax transmission over 1300 m before European contact;8 in the Eastern Highlands no malaria was recorded in early

surveys.10 It is possible, of course, that gene drift and isolation may have a role in the apparently varying prevalence of

426

thalassaemia in the areas studied. There are, however, several reasons why this is unlikely. The migratory and centrifugal spread of the trans-New-Guinea language throughout mainland New Guinea about 10 000 years ago not only gave rise to the closely related upland languages of groups 4-6 (see table) but also to the lowland languages of Madang Province (group 1)." Thus, the groups with the highest and lowest levels of a thalassaemia are linguistically

This work

a

more

closely

related than the other lowland groups.

Council,

Wellcome Trust.

Correspondence should be addressed to S. J. 0., Department of Tropical Paediatrics, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA. REFERENCES 1. Curtain

2.

Furthermore, with triaxial mapping ofABO and MNS blood

frequency, the New Guinea populations fall into four slightly overlapping groups. 12 On two-dimensional representation, the Madang and Sepik populations are separated from the Austronesians by the Highlanders. Thus, group

it also appears from blood group data that the groups with high prevalence of a thalassaemia are more closely related to the group with the lowest prevalence than they are to each other. A possible relation has been reported between altitude and the prevalence of (3 thalassaemia and glucose-6-phosphate dehydrogenase deficiency, two other red-cell disorders thought to afford heterozygous protection against P falciparum malaria, in Papua New Guinea. 1,13 If more extensive population studies of the type reported here demonstrate a similar relation for a thalassaemia, it may be possible to explain why this single-gene disease is so common throughout the world.

was supported by the Wellcome Trust, the Medical Research and the Rockefeller Foundation. S. J. 0. is supported by the

3.

CC, Kidson C, Gajdusek DC, Gorman JG. Distribution pattern, population genetics and anthropological significance of thalassemia and abnormal hemoglobins in Melanesia. Am J Phys Anthropol 1965; 20: 475-83. Beaven GH, Fox RH, Hornabrook RW. The occurrence of haemoglobin-J (Tongariki) and of thalassaemia on Karkar island and the Papua New Guinea mainland. Trans Roy Soc Lond (Biol) 1974; 268: 269. Booth K. Cord blood survey for haemoglobin Bart’s. Papua New Guinea Med J1981;

24: 264-66. 4. Weatherall DJ, Clegg JB. The thalassaemia syndromes, 3rd ed. Oxford: Blackwell Scientific Publications, 1981. 5. Old JM, Higgs DR. Gene analysis. In: Weatherall DJ, ed. The thalassaemias. Edinburgh: Churchill Livingstone, 1980: 74-102. 6. Wurm SA, Hattori S, eds. Language atlas of the Pacific area. Part I: New Guinea area, Oceania, Australia. Pacific Linguistic Series C: 66. Canberra: Australian Academy of Humanities, Japan Academy, 1981. 7. Higgs DR, Weatherall DJ. Alpha thalassemia. Curr Topics Hematol 1983; 4: 37-97. 8. Brittenham G, Lozoff B, Harris JW, et al. Alpha globin gene number: population and restriction endonuclease studies. Blood 1980; 55: 706-08. 9. Vines AP. An epidemiological sample survey of the highlands, mainland and island regions of the territory of Papua New Guinea. Port Moresby: Department of Health, Papua New Guinea, 1970. 10. Peters W, Christian SH, Jameson JL. Malaria in the highlands of Papua and New Guinea. Med J Aust 1958; ii: 782-87. 11. Wurm SA, ed. Papuan linguistic prehistory and past language migrations in the New Guinea area. In: New Guinea area languages and language study, vol 1. Papuan languages and the New Guinea linguistic scene. Series C, 38. Canberra: Australian National University, 1975; 935-56. 12. Booth PB, Simmons RT. Some thoughts on blood genetic work in Melanesia. Papua New Guinea Med J 1972; 15: 10-14. 13. Gorman JG, Kidson C. Distribution pattern of an inherited trait, red cell enzyme

deficiency in New Guinea and New Britain. Am J Phys Anthropol 1962; 20: 347-56.

which has sufficient inertia not to move significantly at the lowest frequencies measured. This mass is supported on the surrounding area of the mother’s skin by a ring platform of such an area that the fetal heartbeat sound waves in the skin underneath it are insufficient to move the mass. "Compliance-matching" gives the additional advantage that airborne noise would now interfere with the heart-sound signal only if it could enter the mother’s body. The skin-to-air interface is now working to the advantage of the system. The signal-to-noise ratio, defined as peak-to-peak valve-closure signal amplitude compared to baseline peak-to-peak signal, lies typically between 10:1and 100:11 (20-40 dB) when the fetal heart lies up to 7 cm below the mother’s skin surface (depth measured in 20 mothers at 30-41 weeks’ gestation with a Kontron Sigma 10 real-time ultrasound scanner). The residual "noise" appears to be physiological-ie, murmurs in blood vessels and valves and abdominal-muscle tremor (fig 2). The signal is well (>60 dB) above electrical noise. Nevertheless unwanted sound can still arise from cable movements; and in the prototypes this has been avoided by fitting a radiotelemetry transmitter. The fetal heartbeat was found to have frequency compo1 nents well outside the previously monitored band of 80-110 Hz.l and The improved signal-to-noise ratio wider bandwidth (20-250 Hz) reveals, in addition to the occurrence of the first and second fetal heart sounds, other details of valve function. Fetal heart-sound signals, abdominal electrocardiographic (ECG) signals, and a 60 Hz clock signal were simultaneously recorded in 8 mass

Methods and Devices NEW TRANSDUCER FOR DETECTING FETAL HEART SOUNDS: USE OF COMPLIANCE MATCHING FOR MAXIMUM SOUND TRANSFER

D. G. TALBERT JOHN D. P. SOUTHALL

DEWHURST

Department of Obstetrics and Bioengineering, Institute of Obstetrics, Queen Charlotte’s Hospital, Goldhawk Road, London W6 0XG THE

signal energy available from fetal heart sounds is greater than

commonly supposed, and the vibrations produced within the heart have a low frequency and contain components that are not audible with a simple stethoscope. A new transducer has been developed to "feel" these vibrations as well as to detect those at audible This high-energy signal with low-frequency components has not been previously exploited, largely because the vibrations are reflected at the boundary between the mother’s skin and the air. This is well known in ultrasound, where it is described as a mismatch of impedance. At the low frequencies associated with heart sounds a similar effect occurs, and it depends largely on the "compliance" (hardness) on either side of the surface. Air is very much "softer" than the mother, and little sound energy escapes to be picked up by a microphone. Moreover, the piezo-electric crystals within microphones that are used to convert these weak pressure waves into an electrical signal are "hard", and so placing them directly on the mother’s skin is also ineffective. This difficulty has been overcome by using a piezo-electric element in the form ofabar clamped at one end and effectively resting on the mother’s skin at the other (fig 1). Pressure waves from the fetal heart press on one end of the bar, causing it to bend and produce an electrical output. The force required to deflect the end varies as bar length -3 , and so by adjusting the length of the bar the force/displacement relationship can be varied. Sound transfer is maximum when this relationship is the same for the end of the bar as for the mother’s skin. The other end of the bar is attached by silicon-rubber clamps to a reference

frequencies.

Fig

I-Section

through the transducer.

The total weight is 100 g.