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Disparate response of monozygotic twins to hepatitis B virus infection
Volume 91 Number 2
Brief clinical and laboratory observations
tion will be delayed. The lack of clinical signs in this infant suggests that the signs associated with "acute" acidosis are related to the central nervous system acidosis which takes several hours to develop. The NH~C1 loading test in this infant demonstrated that he had normal distal acidification mechanisms but that he spilled bicarbonate into his urine until the serum bicarbonate concentration was between 16 and 11 mEq/l. These findings are consistent with a diagnosis of proximal renal tubular acidosis and are similar to the findings of other children with adrenogenital syndrome. ~ Our patient fits into the clinical spectrum of Type IV renal tubular acidosis as defined by Sebastian, McSherry, and Morris. ~ Particular care should be taken in performing NH~C1 loading tests in infants with suspected proximal renal tubular acidosis, since significant bicarbonaturia may continue during the test and further deplete body buffers. As Edelmann and associates' pointed out, the dosage of ammonium chloride should be calculated to lower the total CO~ content to a desired level assuming equal distribution of the acid load throughout total body water. The use of body surface area as a reference point for the calculation of dosage is inappropriate because it provides too high of a dose per total body water for the small
Disparate response of monozygotic twins to hepatitis B virus infection C. J. Peters, M.D., La Jolla, Calif.,
W. C. Reeves, M.D., M.S.P.H.,*
265
infant, since the ratio of total body water to surface area is less in smaller infants. Thus, a standard dose of 150 mEq/m'-' is not appropriate and should be replaced, as Edelmann originally suggested, by a dose calculated on the basis of total body water and existing buffers.
REFERENCES 1. Edelmann CM Jr, Boichis H, Rodriguez-Soriano J, and Stark H: The renal response of children to acute ammonium chloride acidosis, Pediatr Res 1:452, 1967. 2. Comroe H Jr: Physiology of respiration, ed 2, Chicago, 1974, Yearbook Medical Publishers, Inc, p 67. 3. Schmidt CF: Effect of carotid sinus and carotid body reflexes upon respiration, Anesth Analg 19:261, 1940. 4. Asch MJ, Dell RB, Williams GS, Cohen M, and Winters RW: Time course for the development of respiratory compensation in metabolic acidosis, J Lab Clin Med 73:610, 1969. 5. Mitchell RA, Carman CT, Severinghaus JW, Richardson BW, Singer MM, and Shnider S: Stability of cerebrospinal fluid pH in chronic acid base disturbances in blood, J Appl Physiol 20:443. 1965. 6. Oetliker OH, and Zurbrugg RP: Renal tubular acidosis in salt-losing syndrome of congenital adrenal hyperplasia (CAH), J Clin Endocrinol Metab 31:447, 1970. 7. Sebastian A, McSherry E, and Morris RC Jr: Metabolic acidosis with special reference to the renal acidoses, in Brenner BM, and Rector FC Jr: The kidney, Philadelphia, 1976, WB Saunders Company, p 647.
ATTEMPTS to characterize human serum protein polymorphisms resulted in the discovery of Australian antigen (now known as hepatitis B surface antigen or HBsAg). Even after its identification as a marker of hepatitis B virus infection, chronic HBs antigenemia was regarded as a genetic trait. Blumberg and associates 1 and Carbonara and associates ~ have presented studies interpreted as showing autosomal recessive inheritance of HBs antigenemia. We present here studies of a twin pair discordant for HBs antigenemia.
Seattle, Wash., and R. H. Purcell, M.D., Abbreviations used HBs: hepatitis B surface HBsAg: HBs antigen HBV: hepatitis B virus
Bethesda, Md. From the Department of Cellular and Developmental Immunology, Scripps Clinic and Research Foundation, Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, and Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health. *Reprint address: Departmentof Epidemiology, School of Public Health and Community Medicine, SC-36, University of Washington, Seattle, WA 98195.
METHODS We have previously described gel diffusion, counterelectrophoresis, and complement fixation tests for HBsAg. :' The Ausria radioimmunoassay for HBsAg was performed according to manufacturer's directions with values less than 2.1 times control considered negative.
266
Brief clinical and laboratory observations
Antibody to H g s A g was measured by a radioimmunoprecipitation test? I m m u n o g l o b u l i n levels were determined by radial immunodiffusion, and results were expressed relative to the international reference standard. Blood typing was performed with commercial reagents. Haptoglobulin s genotypes were determined by starch gel electrophoresis. The " L " statistic of Nixon was calculated for dermal ridges. 6'~ CASE REPORT
While studying the epidemiology of hepatitis in Panama City, Panama, we obtained blood samples from the family of F. B., a 10-year-old boy with hepatitis. When first seen he had been ill for approximately two weeks with a typical history of fever, malaise, nausea, and dark urine culminating in scleral ieterus. Positive findings were limited to jaundice, hepatomegaly, and serum glutamic-oxalaeetic transaminase concentration of 920 U/ml. He had no history of injection, dental work, or blood transfusion, but hepatitis cases had occurred in his school. Serum did not contain HBsAg when tested by gel diffusion, counterelectrophoresis, complement fixation, or radioimmunoassay. We detected antiHBs by radioimmunoprecipitation. Serum IgM concentration was 437 IU/ml in the initial sample and had decreased to 135 IU/ mI 4 weeks Iater. Subsequent tests for HBsAg and anti-HBs performed one month and 2 years later gave identical results. The patient's twin brother, J. B., had serum HBsAg detectable by complement fixation, counterelectrophoresis, and gel diffusion. His HBsAg persisted through two years at a complement fixation trier of 1:512. Serum glutamic pyruvic transaminase concentration remained normal. Serial serum samples from the patient's mother remained negative for HBsAg and anti-HBs. The father was unavailable for testing. Similarly, other family members, tested for HBsAg and anti-HBs at the same time intervals as the index case, remained either consistently HBsAg, anti-HBs positive, or negative over the two years. The twins were physically indistinguishable. They appeared to be of mixed Spanish and Indian ancestry typical of the Panamanian population. The physician in attendance at their birth examined the placenta and informed the mother that the twins were identical. Their fingerprints had the same general pattern and the discriminant function of Nixon was L = -4.9. For comparison, none of 121 dizygotic twins yielded a value less than --3.5, while 20% of 103 monozygotic twins were below that value. Both twins had blood type O, C +, c +, D +, E - , e + , M +, N +, K - , k + , Fy ~-, Fyb+ and both haptoglobin genotypes were 2.2. DISCUSSION When first sampled, the propositus, F. B., probably had suffered from hepatitis A. Two weeks after onset of hepatitis B, HBsAg is usually detectable by radioimmunoassay; anti-HBs is usually not yet present. The elevated serum IgM level also suggests hepatitis A infection.* His apparently monozygous twin, J. B., maintained the same
The Journal of Pediatrics August 1977
HBsAg titer for two years and must be regarded as a carrier. There was no indication of when either first encountered HBV, but their disparate responses are well documented. When the relationship of HBsAg to HBV infection and later to the HB virion was established, the early interpretations ' -~ of serum HBsAg as a simple " M e n d e l i a n recessive trait" became suspect. The difficulties of proving or disproving this mode of inheritance in h u m a n populations have been discussed. ~ ~o The data presented here, however, strongly support the contention that two genetically identical h u m a n beings have encountered HBsAg with chronic antigenemia resulting in one and an antibody response in the other. This observation offers independent support to open population studies 1.... w h i c h indicated that the interactions between host genome and a variety of epidemiologic factors ultimately determine the chronic carrier state. REFERENCES
1. Blumberg BS, Friedlaender JS, Woodside A, Sutnick AI, and London WT: Hepatitis and Australia antigen: AutosomaI recessive inheritance of susceptibility to infection in humans, Proc Nat Acad Sci USA 62:1108-1115, 1969. 2. Carbonara AO, Trinchieri G, Bedarida G, and Filippi G: A caucasian population with a high frequency of Au 'carriers': Genetic analysis of the condition, Vox Sang 19:228, 1970. 3. Peters CJ, Reeves WC, Rivera V, and Johnson KM: Epidemiology of hepatitis B antigen in Panama, Am J Epidemiol 98:391, 1973. 4. Lander JJ, Giles JP, Purcell RH, and Krugman S: Viral hepatitis, type B (MS-2 strain). Detection of antibody after primary infection, N Engl J Med 285:303, 1971. 5. Smithies O: An improved procedure for starch-gel electrophoresis: Further variations in the serum proteins of normal individuals, Biochem J 71:585, 1959. 6. Nixon WLB: On the diagnosis of twin-pair ovularity and the use of dermatoglyphic data, in Gedda L, editor: Novanti anni delle leggi Mendeliane, Rome, 1955, Instituto Gregorio Mendel, pp 235-245. 7. Hold SB: Inheritance of dermal ridge patterns, in Penrose LS, Brown HL, editorsi Recent advances in human genetics, Boston, 1961, Little Brown & Company, pp 101-119. 8. Peters C J, and Johnson KM: Serum immunoglobin levels in Australia antigen positive and Australia antigen negative hepatitis, Clin Exp Immunol 11:381-391, 1972. 9. Edwards JH: The genetic basis of common disease, Am J Med 34:627, 1963. 10. Petrakis N, Lederberg J: Genetic predisposition to hepatitis, in Vyas GN, Perkins HA, Schmid R, editors: Hepatitis and blood transfusion, New York, 1972, Grune & Stratton, Inc, pp 85-93. 11. Reeves WC, Peters C J, Moon TE, and Purcell RH: Familial clustering of hepatitis B surface antigen among Panamanian Indians, J Infect Dis 131:67, 1975. 12. Szmuness W, Harley E J, and Prince AM: Intrafamilial spread of asymptomatic hepatitis B, Am J Med Sci 270:293, 1975.
Brief clinical and laboratory observations
tion will be delayed. The lack of clinical signs in this infant suggests that the signs associated with "acute" acidosis are related to the central nervous system acidosis which takes several hours to develop. The NH~C1 loading test in this infant demonstrated that he had normal distal acidification mechanisms but that he spilled bicarbonate into his urine until the serum bicarbonate concentration was between 16 and 11 mEq/l. These findings are consistent with a diagnosis of proximal renal tubular acidosis and are similar to the findings of other children with adrenogenital syndrome. ~ Our patient fits into the clinical spectrum of Type IV renal tubular acidosis as defined by Sebastian, McSherry, and Morris. ~ Particular care should be taken in performing NH~C1 loading tests in infants with suspected proximal renal tubular acidosis, since significant bicarbonaturia may continue during the test and further deplete body buffers. As Edelmann and associates' pointed out, the dosage of ammonium chloride should be calculated to lower the total CO~ content to a desired level assuming equal distribution of the acid load throughout total body water. The use of body surface area as a reference point for the calculation of dosage is inappropriate because it provides too high of a dose per total body water for the small
Disparate response of monozygotic twins to hepatitis B virus infection C. J. Peters, M.D., La Jolla, Calif.,
W. C. Reeves, M.D., M.S.P.H.,*
265
infant, since the ratio of total body water to surface area is less in smaller infants. Thus, a standard dose of 150 mEq/m'-' is not appropriate and should be replaced, as Edelmann originally suggested, by a dose calculated on the basis of total body water and existing buffers.
REFERENCES 1. Edelmann CM Jr, Boichis H, Rodriguez-Soriano J, and Stark H: The renal response of children to acute ammonium chloride acidosis, Pediatr Res 1:452, 1967. 2. Comroe H Jr: Physiology of respiration, ed 2, Chicago, 1974, Yearbook Medical Publishers, Inc, p 67. 3. Schmidt CF: Effect of carotid sinus and carotid body reflexes upon respiration, Anesth Analg 19:261, 1940. 4. Asch MJ, Dell RB, Williams GS, Cohen M, and Winters RW: Time course for the development of respiratory compensation in metabolic acidosis, J Lab Clin Med 73:610, 1969. 5. Mitchell RA, Carman CT, Severinghaus JW, Richardson BW, Singer MM, and Shnider S: Stability of cerebrospinal fluid pH in chronic acid base disturbances in blood, J Appl Physiol 20:443. 1965. 6. Oetliker OH, and Zurbrugg RP: Renal tubular acidosis in salt-losing syndrome of congenital adrenal hyperplasia (CAH), J Clin Endocrinol Metab 31:447, 1970. 7. Sebastian A, McSherry E, and Morris RC Jr: Metabolic acidosis with special reference to the renal acidoses, in Brenner BM, and Rector FC Jr: The kidney, Philadelphia, 1976, WB Saunders Company, p 647.
ATTEMPTS to characterize human serum protein polymorphisms resulted in the discovery of Australian antigen (now known as hepatitis B surface antigen or HBsAg). Even after its identification as a marker of hepatitis B virus infection, chronic HBs antigenemia was regarded as a genetic trait. Blumberg and associates 1 and Carbonara and associates ~ have presented studies interpreted as showing autosomal recessive inheritance of HBs antigenemia. We present here studies of a twin pair discordant for HBs antigenemia.
Seattle, Wash., and R. H. Purcell, M.D., Abbreviations used HBs: hepatitis B surface HBsAg: HBs antigen HBV: hepatitis B virus
Bethesda, Md. From the Department of Cellular and Developmental Immunology, Scripps Clinic and Research Foundation, Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, and Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health. *Reprint address: Departmentof Epidemiology, School of Public Health and Community Medicine, SC-36, University of Washington, Seattle, WA 98195.
METHODS We have previously described gel diffusion, counterelectrophoresis, and complement fixation tests for HBsAg. :' The Ausria radioimmunoassay for HBsAg was performed according to manufacturer's directions with values less than 2.1 times control considered negative.
266
Brief clinical and laboratory observations
Antibody to H g s A g was measured by a radioimmunoprecipitation test? I m m u n o g l o b u l i n levels were determined by radial immunodiffusion, and results were expressed relative to the international reference standard. Blood typing was performed with commercial reagents. Haptoglobulin s genotypes were determined by starch gel electrophoresis. The " L " statistic of Nixon was calculated for dermal ridges. 6'~ CASE REPORT
While studying the epidemiology of hepatitis in Panama City, Panama, we obtained blood samples from the family of F. B., a 10-year-old boy with hepatitis. When first seen he had been ill for approximately two weeks with a typical history of fever, malaise, nausea, and dark urine culminating in scleral ieterus. Positive findings were limited to jaundice, hepatomegaly, and serum glutamic-oxalaeetic transaminase concentration of 920 U/ml. He had no history of injection, dental work, or blood transfusion, but hepatitis cases had occurred in his school. Serum did not contain HBsAg when tested by gel diffusion, counterelectrophoresis, complement fixation, or radioimmunoassay. We detected antiHBs by radioimmunoprecipitation. Serum IgM concentration was 437 IU/ml in the initial sample and had decreased to 135 IU/ mI 4 weeks Iater. Subsequent tests for HBsAg and anti-HBs performed one month and 2 years later gave identical results. The patient's twin brother, J. B., had serum HBsAg detectable by complement fixation, counterelectrophoresis, and gel diffusion. His HBsAg persisted through two years at a complement fixation trier of 1:512. Serum glutamic pyruvic transaminase concentration remained normal. Serial serum samples from the patient's mother remained negative for HBsAg and anti-HBs. The father was unavailable for testing. Similarly, other family members, tested for HBsAg and anti-HBs at the same time intervals as the index case, remained either consistently HBsAg, anti-HBs positive, or negative over the two years. The twins were physically indistinguishable. They appeared to be of mixed Spanish and Indian ancestry typical of the Panamanian population. The physician in attendance at their birth examined the placenta and informed the mother that the twins were identical. Their fingerprints had the same general pattern and the discriminant function of Nixon was L = -4.9. For comparison, none of 121 dizygotic twins yielded a value less than --3.5, while 20% of 103 monozygotic twins were below that value. Both twins had blood type O, C +, c +, D +, E - , e + , M +, N +, K - , k + , Fy ~-, Fyb+ and both haptoglobin genotypes were 2.2. DISCUSSION When first sampled, the propositus, F. B., probably had suffered from hepatitis A. Two weeks after onset of hepatitis B, HBsAg is usually detectable by radioimmunoassay; anti-HBs is usually not yet present. The elevated serum IgM level also suggests hepatitis A infection.* His apparently monozygous twin, J. B., maintained the same
The Journal of Pediatrics August 1977
HBsAg titer for two years and must be regarded as a carrier. There was no indication of when either first encountered HBV, but their disparate responses are well documented. When the relationship of HBsAg to HBV infection and later to the HB virion was established, the early interpretations ' -~ of serum HBsAg as a simple " M e n d e l i a n recessive trait" became suspect. The difficulties of proving or disproving this mode of inheritance in h u m a n populations have been discussed. ~ ~o The data presented here, however, strongly support the contention that two genetically identical h u m a n beings have encountered HBsAg with chronic antigenemia resulting in one and an antibody response in the other. This observation offers independent support to open population studies 1.... w h i c h indicated that the interactions between host genome and a variety of epidemiologic factors ultimately determine the chronic carrier state. REFERENCES
1. Blumberg BS, Friedlaender JS, Woodside A, Sutnick AI, and London WT: Hepatitis and Australia antigen: AutosomaI recessive inheritance of susceptibility to infection in humans, Proc Nat Acad Sci USA 62:1108-1115, 1969. 2. Carbonara AO, Trinchieri G, Bedarida G, and Filippi G: A caucasian population with a high frequency of Au 'carriers': Genetic analysis of the condition, Vox Sang 19:228, 1970. 3. Peters CJ, Reeves WC, Rivera V, and Johnson KM: Epidemiology of hepatitis B antigen in Panama, Am J Epidemiol 98:391, 1973. 4. Lander JJ, Giles JP, Purcell RH, and Krugman S: Viral hepatitis, type B (MS-2 strain). Detection of antibody after primary infection, N Engl J Med 285:303, 1971. 5. Smithies O: An improved procedure for starch-gel electrophoresis: Further variations in the serum proteins of normal individuals, Biochem J 71:585, 1959. 6. Nixon WLB: On the diagnosis of twin-pair ovularity and the use of dermatoglyphic data, in Gedda L, editor: Novanti anni delle leggi Mendeliane, Rome, 1955, Instituto Gregorio Mendel, pp 235-245. 7. Hold SB: Inheritance of dermal ridge patterns, in Penrose LS, Brown HL, editorsi Recent advances in human genetics, Boston, 1961, Little Brown & Company, pp 101-119. 8. Peters C J, and Johnson KM: Serum immunoglobin levels in Australia antigen positive and Australia antigen negative hepatitis, Clin Exp Immunol 11:381-391, 1972. 9. Edwards JH: The genetic basis of common disease, Am J Med 34:627, 1963. 10. Petrakis N, Lederberg J: Genetic predisposition to hepatitis, in Vyas GN, Perkins HA, Schmid R, editors: Hepatitis and blood transfusion, New York, 1972, Grune & Stratton, Inc, pp 85-93. 11. Reeves WC, Peters C J, Moon TE, and Purcell RH: Familial clustering of hepatitis B surface antigen among Panamanian Indians, J Infect Dis 131:67, 1975. 12. Szmuness W, Harley E J, and Prince AM: Intrafamilial spread of asymptomatic hepatitis B, Am J Med Sci 270:293, 1975.