Ann. Hum. Genet., Loizd. (1979), 43, 7

7

Printed {n Great Britain

Human aconitase polymorphism in three samples from northeastern Brazil BY ELIANE S. AZEVfiDO, MARIA CHRISTINA B. OLYMPIO DA SILVA, ANGELA MARIA V. MUNIZ DIAS LIMA, EMMANOEL FELIX FONSECA, MARIA MENDES CONCEICAO

Laboratbrio de Gene'tica MCdica, Hospital Prof.Edgard Santos, 40.000 - Salvador, Bahia, Brasil, and Departamento de Biologia, Univ. Federal de Sergipe INTRODUCTION

Two electrophoretic isozyme patterns of human aconitase (E.C. 4 . 2 . 1 . 3 ) have been shown to be controlled by two different loci (Slaughter, Hopkinson & Harris, 1975; Povey et al. 1976). Both ACON,, (mitochondrial) and ACON, (soluble)show some rare variants in Europeans and in Kigerians, but in the latter the frequency of the three most common variants of ACOIV, constitutes a polymorphism (Slaughter et al. 1975). More recently, by means of cell hybridization studies, the ACONs locus has been assigned to chromosome 9 in man (Povey et al. 1976). However, only one other human population survey of ACON, gene frequencies has been reported (Teng et al. 1978) since this genetic polymorphism was first described. In the present paper ACON, gene frequencies are reported in three negroid populations from northeastern Brazil. MATERIAL AND METHODS

Samples The material studied is made up of samples drawn from three different sources. Sample I (newborn liver) was obtained at the Maternidade Tsylla Balbino in Salvador, Bahia. The newborn were either stillborn or had died in the postnatal period. The material was stored at, - 10 "C for about 2 years prior to this investigation (Azevedo, Silva & Tavares-Neto, 1975). Sample I1 (placenta) was also collected at the Maternidade Tsylla Balbino, but from all births. The placenta samples were collected only a few days before the electrophoretic study was done. Sample I11 (placenta) was collected in Aracaju, capital of the State of Sergipe, which is located 320 km north of Salvador. The placenta samples were refrigerated after collection in the delivery room, and subsequently frozen during temporary storage (nearly 30 days) before transportation to the laboratory in Salvador. During transportation from Aracaju to Salvador the samples were kept in iceboxes and refrozen after arrival in the laboratory. The electrophoretic study was carried out a few days later. Race The newborn were subjectively classified into two groups, light and dark, according to the visual degree of Black mixture (Azevedo et al. 1975). I n Samples I1 and I11 the newborns' mothers were also classified for race according to Krieger et ale's(1965) classification modified by Azeddo (1975). 0003-4800/79/0000-4302 $01.00 0 1979 University College London

8

ELIAXE S. A Z E T ~ DASD O

OTHERS

Table 1 . LirCt. cico,iitcise (L4C'0A7&)phenotypes, gene freyzremies and racial distrihutioti of 313 netvborns from Salvador, Baltiu, Brazil Obs.

ACOS, I ACOS, 4 - I ACOX, 4

273 28 3

270.69

9

9.29

0

0.08

I

0.55

I

szm

xcos, 2 - I -ACOX', 2

-4C0Ns +- 2 ACON, 6 - I

10

Esp."

Pl1cnotyprs

ELIANE S. A Z E V ~ DAND O

32'41 0'97

OTHERS

Finally, the luck of enzyme activity in the samples was a matter of great concern. It seems that the longer the storage time (2 years), the greater the frequency of samples without activity (1 2 %,. while in the freshest sample, only 6-2 yo had no activity. Nevertheless, 6 . 2 yo is still a high frequency. If there is some sort of silent allele in the system, it is a matter that cannot be conclnrltd from the present study. SCMIMARY

Huinan aconitase (ACOXs) pol5-morphism was studied in three samples from northeastern Brazil. Two of the samples were collected in the State of Bahia and one in the State of Sergipe. The main characteristic of the samples was given by different degrees of Black admixture. The results showed that the more negroid the samples the higher the frequencies of the alleles ACO,T',4, AC'OL1~~ and &4COAY!.These findings fit well with the known ACOAL gene frequencies in present-day Sigerians and with the past history of Yoruba slaves in Bahia. JVc are gratefiil to JVipberto Cuiilia AzevGdo, l-anilson Silva Souza, Maria Auxiliadora Machado and Jose TRvares S r t o for helping in collecting the samples, and to Dr Jose Maria Magalliiies Neto, Director of fiIatcri~idadeTqy11a Ralbiiio. for giviiig 11s permission to carry out the work.

REFERENCES

,SLEV&T,O. E. S . ( 1 9 i 5 ) .0 bistema gen6tico das desidrogenases alco6licas em mestipos da Bahia e em brancos europem. Thes~s,t-iiiv.Fed. Bahia, Brazil. AZLV&I)O. E. S.. S I L ~ A31. . C. B. 0. & TAVARES-XETO, J. (1975). Human alcohol dehydrogenase A D H , , A D H , aiid A D H , locv i n 5 mixed population of Bahia, Brazil. Ann. H u m . Genet., Lond. 39, 321. KRIELEH. H., MORTOS,S . E., MI, fif. P., AZEV&DO, E. S., FREIRE-MAIA,N.& YASUDA,N. (1965). Racial admixture 111 Xortlicvtstcrn Brazil. A n n . H u m . Genet., Lond. 29, 113. Povm, S., SLAT-GHTER. C . X.,Wusow. D. E., GORMLEY, I. P., BVCKTON, K. E., PERRY,P. & BOBROW, M. ( 1 9 7 6 ) . E\idencc for the assignment of the loci A K , , A K , and ACON, to chromosome 9 in man. Ann. Hum. Genet, Lond. 39, 413. SALZASO.F. &I. 8: FREIRE-JIAIA, IT.(1970). Problems in H u m a n Biology. A Study of Brazilian Populations, pp. 38-45 Detroit : JVayne State University Press. SL~IXHTER, C . X.. H o r ~ ~ i s s oD. x , -4.& HARRIS, H. (1975). Aconitase polymorphism in man. Ann. Hum. Genet., Lond. 39. 193. TESG,T.S., TAT,S. G.. SG, T. Br LOPEZ,C. G. (1978).Red cell glyoxalase I and placental soluble aconitase polymorphisins in the three major ethnic groups of Malaysia. J ap. J . H u m . Genet. 23, 211. \ ~ E a c ; m ,P. (1976). Trade Relations between the Bight of Benin and Bahia f r o m t?Le 17th to 19th century, pi'. 1 - 7 . Ibadaii IJni\ ersity Press.

Human aconitase polymorphism in Brazil

9

Table 3. Placenlal aconitase (ACON,) phenotypes, gene frequencies and racial distribut~o?~ of 147 newborns and newborns’ mothers from Aracuju, Sergipe, Brazil Phenotypes

ACON, I ACON, 4 - I ACON, 4

Obs.

I43 3 I

Exp.*

142’04 4’91 0.05

Gene frequencies : ACONA = 0.9829;ACON; = 0.0171 Racial distribution of newborns :t Light, n = I 10 (0.846) ; dark, n = 20 (0’154) Racial distribution of newborns’ mothers :I. Light, 12 = 93 (0.715); medium, 12 = 28 (0.215);dark, 72 = 9 (0.070)

* 7

Expected under Hardy-Weinberg equilibrium. Seventeen newborns were not classified for race. Seventeen mothers were not classified for race.

placental samples are given in Tables 2 and 3. I n Sample I1 20 showed no aconitase activity and in Sample I11 12 showed no activity. DISCUSSION

The population of northeastern Brazil is characterized by a tri-racial mixture of Europeans, mostly Portuguese, African Negroes and native Indians (Krieger et al. 1965). Unfortunately, there are no accurate historical records of the original racial groups of the slaves brought to Brazil as all documents related to slavery in Brazil were publicly burnt on 18 December 1890 by decree of the Minister of Finances. However, there are some studies showing that the strong predominance of Yoruba customs in Bahia is explained by a massive arrival of Nago-Yoruba slaves after 1770 (Verger, 1976). However, the slave traffic to Brazil probably started since the first half of the sixteenth century, and for nearly three centuries the city of Salvador, in Bahia, was the main port for arrival and distribution of slaves (Salzano & Freire-Maia, 1970). On the other hand, the occurrence of racial intercrosses in northeastern Brazil has its greatest evidence in the present-day population itself which shows a continuous variety of negroid phenotypes ranging from the ‘lightest white’ to the ‘darkest black’. I n the present work, in Samples I and T I , which are from Salvador-Bahia, the frequency of Clark newborn is higher than in Sample I11 which is from another State. Also, within the two samples from Salvador there are more dark newborns in Sample I than in Sample 11. These differences in the degree of black admixtures in the three samples, are in parallel with the observed variations in the ACON, gene frequencies : the higher the frequency of dark newborns, the higher the frequencies of ACONg, ACON; and ACON; alleles (see Tables 1 , 2 and 3). Sample 111,for example, has the lowest frequency of dark newborns, as well as the lowest frequency of ACOIY,4, and absence of ACON; and ACON; alleles. These findings fit well with the ACON, gene frequencies in present-day Nigerians (Slaughter et al. 1975) and with the past history of Yoruba slaves in Bahia (Verger, 1976). These data also suggest that the ACON, gene frequencies in the Portuguese may be similar to what has been described for other European populations (Slaughter et al. 1975).If the ACON;, ACON; and ACOIV; alleles were also frequent in the Portuguese the effect of Black admixture on gene frequencies shown in Tables I , 2 and 3 would not be detectable.

10

ELIANE S. A Z E V ~ DAKD O

OTHERS

Finally, the lack of e n z p e actiritv in tht: samples was a matter of great concern. It seems that the longer the storage time ( 2 years), the greater the frequency of samples without activity ( 1 2 % ) . while in the freshest sample, only 6.2% had no activity. Nevertheless, 6.276 is still a high frequency. If there is some sort of silent allele in the system, it is a matter that cannot be concliidcd from the present stud;v. St'MMARY

Human aconitase (dCOX.) polj-morphisni was studied in three samples from northeastern Brazil. Tw) of the samples were collected in the State of Bahia and one in the State of Sergipe. The main characteristic of the samples was given by different degrees of Black admixture. The results showed that the more negroid the saniples the higher the frequencies of the alleles ACO,Vt. AC'OX: and ACTS:. These findings fit well with the known ACONs gene frequencies in prcmnt-day Siperians and with the past history of Yoruba slaves in Bahia. \SP di c . pratefid to \Vigberto Cunlia Azevedo, Vaiiilson Si1.r-a Souza, Maria Auxiliadore Machado and Josh Tax ares S r t o for lielpiiig in collecting the sainples, and to Dr Jose Maria MagalhBes Neto, Director of Rlutcriudnde Ts) 11,t Ralbino. for gi.r-ing us permission to carry out the work.

REE ERERCES

AZEV~~DO. E h. (1975). 0 sistema geiiCtico das desidrogenases alco6licas em mestiqos da Bahia e em brancos etirupeus. Thesis. X T ~ u vFed. . Bahia, Brazil. Azr~vGuo,F:.S.. SILVA.&I. C. €3. 0. gt TAVARES-SETO, J. (1975). Human alcohol dehydrogenase ADH,, A D H Larid AUH, loci i n a mixed population of Bahia, B r a d . Ann. H u m . Genet., Lond. 39, 321. KRIE(.ER. H., M O R T O ~3. . E.. MI, M. P., X Z E V ~ D O E., S., FREIRE-MAIA, N. gt YASUDA, N. (1965). Racial adinixture i i i Sortlieastern Brazil. Ann. H u m . Genet., Lond. 29, 113. P o v ~ rh.. , SLAI*GHTER. C' A, WILSON,D. E., GOI:MLEY,I. P., BUCKTON, K. E., PERRY, P. & BOBROW, M. (1976). Ewdencc for t h c assignment of the loci A K , , A K , and ACOArs t o chromosome 9 in man. Ann. Hum. G'e~zet. Lond. 39. 413. SALZAYO, F.M. 8- F a E I n s - ? t I A r A , S. (1970). Problems in Human Biology. A S t u d y of Brazilian Populations, pi'. 38 -46. Ih.troit. Il-ayiir State University Press. SLAUGHTER, C d.,H o ~ ~ r s s oD. s . -2.& HARRIS,H. (1975). Aconitase polymorphism in man. Ann. H u m . Genet., Lond 39. 193. TEX:, T.S., TAY,S. G.. SG,T. & LOPEZ,C . G. (1978). Red cell glyoxalase I and placental soluble aconitase polpmrphisms 111 tlir three major ethnic group': of Malaysia. J a p . J . Hum. Genet. 23, 211. YERGEII.P. (1971;) Trade Kelatbons between the Iizghl of Benin and Bahia from the 17th to 19th century, p p . 1 7. Ibadaii Vriivi.r.itg Press