Hum. Hered. 27: 433-436 (1977)
Atypical (E‘i) and Fluoride-Resistant (E|) Cholinesterase Genes: Absent in a Native American Indian Population P h il ip J. G arry Department of Pathology and Clinical Nutrition Program. University of New Mexico School of Medicine, Albuquerque, N. Mex.
Key Words. Plasma cholinesterase • Genetic variants • American Indians • Population study
Identification of individuals who demonstrate abnormal resistance and hypersensitivity to the muscle relaxant suxamethonium (succinylcholine) has led to discovery of a number of genetic variants of serum cholinesterase (Enzyme Commission designation, acylcholine acyl-hydrolase EC 3.1.1.8). Because of pharmacogenetic interrelationships and increased interest in human genetic polymorphism, the frequency of serum cholinesterase mu tants has been determined in many populations for alleles of the E, locus, as well as, the E2 locus [1-6]. Alleles of the Ej locus control synthesis of serum cholinesterase variants and can be identified using selective inhibitors in the enzymatic assay, e.g.. dibucaine and sodium fluoride [7. 8]. It is gener ally agreed that at least four alleles exist at the E, locus: Ey for usual or normal esterase: Ey for atypical esterase: E[ lor fluoride-resistant type and Ej for the silent gene [9], A new allele at the E, locus has recently been reported and termed Ej [10.11], The Ej allele results in a 65-70% reduction in the number of circulating enzyme molecules and can be identified only when combined in the genotypic form Ej'Ej or EjEj. Altogether, these five alleles account for 15 different genotypes which can be identified by biochemical and/or pedigree studies. The C} variant of serum cholinesterase is controlled by the E., locus and can be identified only by electrophoretic techniques [12].
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Abstract. A population of 358 Navajo Indian children screened for serum cholinestera se variants failed to show the presence of either atypical or fluoride-resistant genes. This is the first significant anthropological observation of the absence of both variants in a native North American population.
434
G arry
In the spring of 1974. venous blood samples were obtained from 358 Navajo child ren enrolled in the Toyci Boarding School, an elementary school for Navajo children located in Steamboat, Arizona. Children ranged in age from 6 through 15 years and all lived at the school, although approximately one third returned to their Reservation home on any gevin weekend. Scrum cholinesterase genotypes were determined using sodium fluoride as a selective inhibitor in 0.05 molar Tris and phosphate buffers, pH 7.4. using 2.0 millimolar bulyrylthiocholine iodine as substrate (13,14], We did not examine specimens for the C J variant.
Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
All children examined were found to be homozygous for the usual form of the enzyme except for one child who was identified as heterozygous atypi cal (E“E|). This child was excluded from final data analysis because his father was known not to be Navajo. The complete absence of both atypical and fluoride-resistant genes in this native North American Indian population is similar to that in native South American populations where 491 individuals belonging to two Venezuelan and Bolivian tribes failed to demonstrate either the atypical or fluoride-re sistant gene [15], However. L isker el al. [16] found a frequency of 0.005 for the atypical gene, E", in 13 tribes of Mexican Indians. In an earlier report L isker et al. [17] found a frequency of 0.009 for the atypical gene. E,. in 377 Mexican Indians who belonged to 4 different linguistic groups. The latter report stated that the individuals examined were apparently ‘pure’ Indians, but blood group studies showed the existence of a small degree of admixture with Caucasians. Frequency of the fluoride-resistant gene was not determined in studies reported by L isker el al. [16, 17], T ashian el al. [18] screened a population of Xavante Indians of the Brazilian Mato Grasso and encoun tered no serum cholinesteiase variants. These findings suggest that both atyp ical and fluoride-resistant genes were either absent or had an extremely low frequency among ancestors of present day Amerindians. In an earlier study we noted the absence of atypical gene among III White Mountain Apache children while ascertaining frequencies of serum cholinesterase E, and Ej all eles in a cross-sectional representation of US Caucasian children to be 0.0177 and 0.0066, respectively [13, 14]. The frequency of atypical and fluorideresistant alleles in US Caucasian children is similar to reported frequencies for these two variants found in European countries [6], Our finding has practical significance and should be of interest to popu lation geneticists and anthropologists. Prolonged apnea due to suxametho nium sensitivity often occurs in individuals heterozygous and homozygous for the atypical and fluoride-resistant variants (Ej'E',: Ej'Ej'; E[E',). The chance of this happening among Navajo Indians should be extremly rare. The data
Plasma Cholinesterase Studies in Native American Indians
435
also indicate that the gene pool of this native Noth American Indian popu lation. like that of South American Indians, has remainde relatively stable with little admixture with those races, primarily Caucasian, demonstrating atypical and flouride-resistant genes.
References 1 Lubin, A .H.and G arry, P.J.: Sex and population differences in the incidence of a plasma cholinesterase variant. Science 173: 161-164 (1971). 2 W hittaker. M .: The frequency of the fluoride resistant gene in a population of British students. Acta Genet., Basel IS: 563-566 (1968). 3 W hittaker, M.: Frequency of a atypical pseudocholincstcrasc in groups of indivuals of different ethnographical origin. Acta Genet., Basel IS: 567-572 (1968). 4 M otulsky, A.C.and Morrow , A.: Atypical cholinesterase gene E“. Rarity in Ne groes and most Orientals. Science 159: 202-203 (1967). 5 Simpson, N.E.and K alow , W.: Comparisons of two methods for typing of serum cholinesterase and prcvalance of its variants in a Brazilian population. Am.J. hum. Genet. 17: 156-162 (1965). 6 A ltland , K.: Bucher, R.; K in, T.W .: Busch, H.: Brockelmann, C., and G oedde, H. W.: Population genetics studies on pseudocholinesterase polymorphism in Germany. Czechoslovakia, Finland and among Laps. Humangenetik S: 158-161 (1969). 7 K ai.ow , W.and G knest, K.: A method for the detection of atypical forms of human serum cholinesterase. Determination of dibucaine numbers. Can.J. Biochem..?.5: 339 346 (1957). 8 H arris, H.and W hittaker, M.: Differential inhibition of human serum cholineste rase with fluoride. Recognition of two new phenotypes. Nature, Lond. 191: 496-498 (1961). 9 LaD u, D.N.: Isoniazid and pseudocholinesterase polymorphism. Fed. Proc. J /: 1276— 1283 (1972). 10 G arry, P.J.: D ietz, A.A.: L ubrano, T.: F ord , PC.: J ames, K.. and R ubinstein, H. M.: New allele at cholinesterase locus I, .1.med.Genet. 13: 38-42 (1976). 11 R ubinstein, H.M .; D ietz, A. A.; L ubrano, T., and G arry. P.J.: Ej, a quantitative variant at cholinesterase locus I. Immunologic evidence. J. med. Genet. 13: 43-45 (1976). 12 H arris, H.; Hopkinson . D.A.. and R obson, E.B.: Two-dimensional electrophoresis of pseudocholinesterase components in normal human serum. Nature. Lond. 196: 1296-1298 (1962). 13 G arry, P. J.: A manual and automated procedure for measuring scrum cholinesterase activity and identifying enzyme variants. Clin.Chem. 77: 1972 198 (1971). 14 G arry, P.J.: O wen, G.M.. and L ubin , A .H .: Identification o f serum cholinesterase fluoride variants by differential inhibition in Tris and phosphate buffers. Clin.Chem. Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
IS : 105-109 (1972).
436
G arry
15 A rends, T.; D avis, A.A., and L ehmann, H.: Absence of variants of usual serum pscudocholinesterase (acylcholine acylhydrolase) in South American Indians. Acta Genet.. Basel 17: 13 16 (1976). 16 Liskir . R.: Z araie , G., and R odriguez , E.: Studies on several genetic hematological traits of the Mexican population. Am.J.phys. Anthrop. 27: 27 32 (1976). 17 Lisker, R.: M oral, D. D el, and Loria . A.: Frequency o f the atypical pseudocholine sterase in four Indian (Mexican) tribes. Nature, Loud. 202 : 815 (1964;. 18 T ashian, R .E .: Brewer, G .J.; L ehmann, H.: D avies. D .A .. and R ucknazel, D .L.: Further studies on Xavante Indians. Am.J . Genet. 19: 524 531 (1967).
Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
P hilip J . G arry, Ph.D.. Director, Clinical Nutrition Laboratory, Department of Path ology. University of New Mexico School of Medicine, Albuquerque, NM S71.ll (USA)
Atypical (E‘i) and Fluoride-Resistant (E|) Cholinesterase Genes: Absent in a Native American Indian Population P h il ip J. G arry Department of Pathology and Clinical Nutrition Program. University of New Mexico School of Medicine, Albuquerque, N. Mex.
Key Words. Plasma cholinesterase • Genetic variants • American Indians • Population study
Identification of individuals who demonstrate abnormal resistance and hypersensitivity to the muscle relaxant suxamethonium (succinylcholine) has led to discovery of a number of genetic variants of serum cholinesterase (Enzyme Commission designation, acylcholine acyl-hydrolase EC 3.1.1.8). Because of pharmacogenetic interrelationships and increased interest in human genetic polymorphism, the frequency of serum cholinesterase mu tants has been determined in many populations for alleles of the E, locus, as well as, the E2 locus [1-6]. Alleles of the Ej locus control synthesis of serum cholinesterase variants and can be identified using selective inhibitors in the enzymatic assay, e.g.. dibucaine and sodium fluoride [7. 8]. It is gener ally agreed that at least four alleles exist at the E, locus: Ey for usual or normal esterase: Ey for atypical esterase: E[ lor fluoride-resistant type and Ej for the silent gene [9], A new allele at the E, locus has recently been reported and termed Ej [10.11], The Ej allele results in a 65-70% reduction in the number of circulating enzyme molecules and can be identified only when combined in the genotypic form Ej'Ej or EjEj. Altogether, these five alleles account for 15 different genotypes which can be identified by biochemical and/or pedigree studies. The C} variant of serum cholinesterase is controlled by the E., locus and can be identified only by electrophoretic techniques [12].
Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
Abstract. A population of 358 Navajo Indian children screened for serum cholinestera se variants failed to show the presence of either atypical or fluoride-resistant genes. This is the first significant anthropological observation of the absence of both variants in a native North American population.
434
G arry
In the spring of 1974. venous blood samples were obtained from 358 Navajo child ren enrolled in the Toyci Boarding School, an elementary school for Navajo children located in Steamboat, Arizona. Children ranged in age from 6 through 15 years and all lived at the school, although approximately one third returned to their Reservation home on any gevin weekend. Scrum cholinesterase genotypes were determined using sodium fluoride as a selective inhibitor in 0.05 molar Tris and phosphate buffers, pH 7.4. using 2.0 millimolar bulyrylthiocholine iodine as substrate (13,14], We did not examine specimens for the C J variant.
Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
All children examined were found to be homozygous for the usual form of the enzyme except for one child who was identified as heterozygous atypi cal (E“E|). This child was excluded from final data analysis because his father was known not to be Navajo. The complete absence of both atypical and fluoride-resistant genes in this native North American Indian population is similar to that in native South American populations where 491 individuals belonging to two Venezuelan and Bolivian tribes failed to demonstrate either the atypical or fluoride-re sistant gene [15], However. L isker el al. [16] found a frequency of 0.005 for the atypical gene, E", in 13 tribes of Mexican Indians. In an earlier report L isker et al. [17] found a frequency of 0.009 for the atypical gene. E,. in 377 Mexican Indians who belonged to 4 different linguistic groups. The latter report stated that the individuals examined were apparently ‘pure’ Indians, but blood group studies showed the existence of a small degree of admixture with Caucasians. Frequency of the fluoride-resistant gene was not determined in studies reported by L isker el al. [16, 17], T ashian el al. [18] screened a population of Xavante Indians of the Brazilian Mato Grasso and encoun tered no serum cholinesteiase variants. These findings suggest that both atyp ical and fluoride-resistant genes were either absent or had an extremely low frequency among ancestors of present day Amerindians. In an earlier study we noted the absence of atypical gene among III White Mountain Apache children while ascertaining frequencies of serum cholinesterase E, and Ej all eles in a cross-sectional representation of US Caucasian children to be 0.0177 and 0.0066, respectively [13, 14]. The frequency of atypical and fluorideresistant alleles in US Caucasian children is similar to reported frequencies for these two variants found in European countries [6], Our finding has practical significance and should be of interest to popu lation geneticists and anthropologists. Prolonged apnea due to suxametho nium sensitivity often occurs in individuals heterozygous and homozygous for the atypical and fluoride-resistant variants (Ej'E',: Ej'Ej'; E[E',). The chance of this happening among Navajo Indians should be extremly rare. The data
Plasma Cholinesterase Studies in Native American Indians
435
also indicate that the gene pool of this native Noth American Indian popu lation. like that of South American Indians, has remainde relatively stable with little admixture with those races, primarily Caucasian, demonstrating atypical and flouride-resistant genes.
References 1 Lubin, A .H.and G arry, P.J.: Sex and population differences in the incidence of a plasma cholinesterase variant. Science 173: 161-164 (1971). 2 W hittaker. M .: The frequency of the fluoride resistant gene in a population of British students. Acta Genet., Basel IS: 563-566 (1968). 3 W hittaker, M.: Frequency of a atypical pseudocholincstcrasc in groups of indivuals of different ethnographical origin. Acta Genet., Basel IS: 567-572 (1968). 4 M otulsky, A.C.and Morrow , A.: Atypical cholinesterase gene E“. Rarity in Ne groes and most Orientals. Science 159: 202-203 (1967). 5 Simpson, N.E.and K alow , W.: Comparisons of two methods for typing of serum cholinesterase and prcvalance of its variants in a Brazilian population. Am.J. hum. Genet. 17: 156-162 (1965). 6 A ltland , K.: Bucher, R.; K in, T.W .: Busch, H.: Brockelmann, C., and G oedde, H. W.: Population genetics studies on pseudocholinesterase polymorphism in Germany. Czechoslovakia, Finland and among Laps. Humangenetik S: 158-161 (1969). 7 K ai.ow , W.and G knest, K.: A method for the detection of atypical forms of human serum cholinesterase. Determination of dibucaine numbers. Can.J. Biochem..?.5: 339 346 (1957). 8 H arris, H.and W hittaker, M.: Differential inhibition of human serum cholineste rase with fluoride. Recognition of two new phenotypes. Nature, Lond. 191: 496-498 (1961). 9 LaD u, D.N.: Isoniazid and pseudocholinesterase polymorphism. Fed. Proc. J /: 1276— 1283 (1972). 10 G arry, P.J.: D ietz, A.A.: L ubrano, T.: F ord , PC.: J ames, K.. and R ubinstein, H. M.: New allele at cholinesterase locus I, .1.med.Genet. 13: 38-42 (1976). 11 R ubinstein, H.M .; D ietz, A. A.; L ubrano, T., and G arry. P.J.: Ej, a quantitative variant at cholinesterase locus I. Immunologic evidence. J. med. Genet. 13: 43-45 (1976). 12 H arris, H.; Hopkinson . D.A.. and R obson, E.B.: Two-dimensional electrophoresis of pseudocholinesterase components in normal human serum. Nature. Lond. 196: 1296-1298 (1962). 13 G arry, P. J.: A manual and automated procedure for measuring scrum cholinesterase activity and identifying enzyme variants. Clin.Chem. 77: 1972 198 (1971). 14 G arry, P.J.: O wen, G.M.. and L ubin , A .H .: Identification o f serum cholinesterase fluoride variants by differential inhibition in Tris and phosphate buffers. Clin.Chem. Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
IS : 105-109 (1972).
436
G arry
15 A rends, T.; D avis, A.A., and L ehmann, H.: Absence of variants of usual serum pscudocholinesterase (acylcholine acylhydrolase) in South American Indians. Acta Genet.. Basel 17: 13 16 (1976). 16 Liskir . R.: Z araie , G., and R odriguez , E.: Studies on several genetic hematological traits of the Mexican population. Am.J.phys. Anthrop. 27: 27 32 (1976). 17 Lisker, R.: M oral, D. D el, and Loria . A.: Frequency o f the atypical pseudocholine sterase in four Indian (Mexican) tribes. Nature, Loud. 202 : 815 (1964;. 18 T ashian, R .E .: Brewer, G .J.; L ehmann, H.: D avies. D .A .. and R ucknazel, D .L.: Further studies on Xavante Indians. Am.J . Genet. 19: 524 531 (1967).
Downloaded by: Nagoya University 133.6.82.173 - 1/13/2019 9:38:19 AM
P hilip J . G arry, Ph.D.. Director, Clinical Nutrition Laboratory, Department of Path ology. University of New Mexico School of Medicine, Albuquerque, NM S71.ll (USA)
