Humangenctik 27, 137--140 (1975) © by Springer-Verlag 1975

Imm.unoglobulin Allotypes in Portugal* Teresa Martins P e r e i r a a n d Carlos Manso Institute of Physiological Chemistry, Faculty of ~edieine of Lisbon, Lisbon, Portugal Received November 4, 1974

Summary. The frequency of several immunoglobulin allotypes has been evaluated in a sample of 419 Portuguese subjects. It was found that the percentage of Gm (1) and of Gin(2) are among the highest in Europe, although Portugal is situated in the extreme southwest of Europe. A few cases of dissociation of Gm(1) and Gin(21) were noted and attributed to the probable presence of African admixture. Introduction

The p o l y m o r p h i s m of h u m a n i m m u n o g l o b u l i u s k n o w n as a l l o t y p e s has been used w i d e l y in t h e p a s t 10 y e a r s for t h e s t u d y of p o p u l a t i o n genetics. E s p e c i a l l y t h e Gm factors of i m m u n o g l o b u l i n G h a v e p r o v e d to be an excellent tool for this p u r p o s e a n d are considered m o s t a d v a n t a g e o u s in c o m p a r i n g different racial groups a n d e v a l u a t i n g t h e p e r e e n t a g e of a d m i x t u r e between different ethnic groups. g o p a r t z (1971) a n d Steinberg (1969) reviewed t h e results of a large n u m b e r of studies done w i t h t h e Gm allotypes in m a n y countries of t h e world. As no such s t u d y h a d ever been done in P o r t u g a l , we present t h e results of our work w i t h t h e P o r t u g u e s e population. As a result of its geographic situation, Portugal has all the reasons to present a very heterogenous mixture of genes from many populations. Because it is situated at the extreme West of Europe, invaders were forced to settle there and mix with the previous inhabitants. After the 16th century, Portuguese expansion in the world resulted in the arrival of distant peoples from India, China, Africa, and South America, who were also absorbed. We may consider the main contributors to the formation of the present-day Portuguese to be: a Celtic people, the Lusitanians, who lived in the country for centuries before the Christian era; the Romans, who invaded the country shortly before Christ; Germans (Goths, Vandales, Sueves), who were mainly located in the north; and Arabs, who came from the south. Pirates and merchant ships brought Greeks, Phcnitians, Vikings, and Arabs to the coastal area. After the 16th century a large number of Negros and a few Indians and Chinese also arrived. Finally, in the 19th century the country was invaded by the French troops of Napoleon. On t h e m a p , we d e p i c t t h e five regions t h a t are included in our s t u d y . Minho has a large stock of G e r m a n i c ancestry. B e i r a is m o s t l y Celtic, R o m a n , a n d Jewish. L i t o r a l is t h e coastal zone b e t w e e n t h e rivers D o u r o a n d Tejo w i t h m a n y small h a r b o r s where sea peoples f r e q u e n t l y settled. A l e n t e j o encompasses t h e area between t h e river, Tejo a n d Algarve, w i t h a p o p u l a t i o n including Moors, Celts, * Supported by Instituto de Alta Cultura (Project LMC-10) and the CMouste Gulbenkian Foundation.

138

T.M. Pereira and C. Manso

/ Minho

/

/ / /

/ /

/ /

/

I

~. i¢/

Beiras

!

Alentejo

A[garve

Fig. 1 N e g r o s , a n d others. A n d finally, A l g a r v e , w h i c h has t h e h i g h e s t p e r c e n t a g e o f B e r b e r s f r o m t h e n o r t h o f Africa.

Material and Methods Blood was drawn in schools and blood banks and allowed to clot for serum extraction. No special importance was attached to age or sex, but every subject was carefully checked for his place of birth and that of his parents. I f donor and parents were from distant places, the subject would be discarded. Gm allotypes were determined by the agglutination-inhibition technique. Antisera were obtained from Dr. Ropartz and their classification is described in Table 1. Table 1. Reagents applied in the Gm determinations (all obtained from Dr. Ropartz) Allotypes

Agglutinating serum

Anti-D

Gm 1 Gm 2 Gm 4 Gm~ Gml0 Gm25 Gm~l

LAR LE~ GIR ALL or BEN LET GRA L 224 A

276 276 275 275 275 275 287

Immunoglobulin Allotypes in Portugal

139

Two studies were done. The first encompasses 72 subjects from the village of Alfeizer~o (see map). This was a pilot study in which only a few alltypes were analyzed. The second study includes 419 subjects from the north to south of Portugal; in this one a larger number of Gm allotypcs was detected, including Gm(1), Gm(2), Gin(4), Gin(5), Gm(10), Gin(21), and Gin(25). Results

T h e r e s u l t s of t h e p i l o t s t u d y are g i v e n i n T a b l e 2 a n d t h o s e of t h e s e c o n d s t u d y are s h o w n i n T a b l e s 3 a n d 4. Table 2. Gm allotypes in the village of Alfeizer~o Number of subjects Gm (1) Gm (21) Gm (1, 21) Gm (1, 21--) Gm (5, 10, 11) Gm (5) homozygous Gm (1, 21) homozygous Gm (5, 21) heterozygous

72 54% 54% 54% 0% 92% 46% 7% 47%

Table 3. Gm phenotypes found in Portugal Phenotypes

No.

Gm Gm Gm Gm Gm Gm

53 9 136 17 16 188

13 2 32 4 4 45

419

100

(1, 2, 4, 5, 10, 21, 25) (1, 2, 4--, 5--, 10--, 21, 25--) (1, 2--, 4, 5, 10, 21, 25) (1, 2--, 4, 5, 10, 21--, 25) (1, 2--, 4--, 5--, 10--, 21, 25--) (1--, 2--, 4, 5, 10, 21--, 25)

Total

%

Table 4. Gm allotypes in 5 different areas of Portugal Minho Number of subjects

Beira

Litoral

Alentejo Algarve

Total

20

38

91

36

234

419

55 55 55 0 95 95 25 75 100 0 95 5 45 5 50

68 66 66 2 95 95 11 89 100 0 95 5 31 5 64

60 56 56 4 89 89 14 86 100 0 89 11 40 11 49

61 60 60 1 97 97 14 86 100 0 97 3 39 3 58

49 45 45 4 94 94 16 84 100 0 94 6 51 6 43

57 51 51 3 93 93 15 85 100 0 93 7 43 7 50

Allotypes (percentage) Gm (1) Gm (21) Gm (1, 21) Gm (1, 21--) Gm (4) Gm (5, 10, 25) (1, 2) (1, 2--) (1, 2, 21) (1, 2, 21--) (4, 5) (4--, 5--) Homoz (4, 5) Homoz (1, 21) Heteroz (1, 4, 5, 21)

140

T.M. Pereira and C. Manso

Discussion The two studies described do n o t show v e r y i m p o r t a n t differences, e x c e p t for t h e fact t h a t no dissociations G i n ( l , 2 1 ) are f o u n d in t h e first. I n r e g a r d to t h e second s t u d y , t h e following seem to be t h e m o s t i m p o r t a n t points : 1. The p e r c e n t a g e of Gm(1) is a m o n g t h e highest in E u r o p e , c o n t r a d i c t i n g t h e idea t h a t G i n ( l ) increases with l a t i t u d e (Ropartz, 1963, 1964, 1968). 2. The same can be said of t h e percentage of Gm(2). This a l l o t y p e is positive a n d always a c c o m p a n i e s Gin(l), which is usual in Caucasians. 3. I n 3~o of t h e cases studied, t h e r e is a dissociation of t h e Gm factors 1 a n d 21, t h e second being n e g a t i v e when t h e first is positive. W e a t t r i b u t e this fact to t h e p r o b a b l e presence of African genes, w i t h which Gm 1 a n d s are u s u a l l y associated. I t is interesting t h a t in t h e D a n i s h p o p u l a t i o n t h e same p e r c e n t a g e of dissociation was found (Ropartz, 1960). 4. The p h e n o g r o u p Gm(4, 5,10, 25) is always i n h e r i t e d en bloc, a n d no dissociations were found. 5. W h e n we e v a l u a t e t h e percentage of t h e a l l o t y p e s in t h e 5 areas into which we divide t h e country, some differences are found a m o n g t h e m ; n a m e l y , Minho, of p r e d o m i n a n t l y G e r m a n ancestry, has no dissociations (1, 2 1 - - ) a n d t h e r e t h e f r e q u e n c y of Gm(2) is t h e highest. T h e highest percentages of G m ( 1 , 2 1 - - ) are f o u n d in L i t o r a l a n d Algarve, as should be expected, in its African settlements. The value of this l a s t s t u d y is s o m e w h a t lessened b y t h e small n u m b e r s of cases included in some of t h e areas.

Acknowledgements. The authors thank Dr. Almerindo Lena from the blood bank of ttospital de S. Jos6, in Lisbon, and Dr a Maria Antonieta Contreiras from Faro, Algarve, for the facilities granted in collecting blood specimens. Also, Dr. C. Ropartz and Mme. Liliane P~ivat of Rouen and their staff must be thanked for teaching one of us, and for all the information given during the execution of this work. References Ropartz, C.: L'allotypie des immunoglobulines humaines. Bull. Inst. Pasteur 69, 107--152 (1971) Ropartz, C., Rivat, L., Rousseau, P. : Observations on the distribution of the Gm and Inv groups in Hungary. Humangenetic 6, 165--169 (1968) Ropartz, C., Rivat, L., l~ousseau, P., Baitseh, H., Van Loghen, J. : Les syst6mes G m e t Inv en Europe. Acta genet. (Basel) 13, 109--123 (1963) Ropartz, C., Rivat, L., Rousseau, P., Lauridsen, U., Persson, I. : A survey of 9 Gm factors, the Inv and the Isf systems in Danes. Hum. ttered. 20, 275--280 (1970) Ropartz, C., Walter, H., Arndt-Hanser, A., Rivat, L., Rousseau, P., Bernhard, W.: On the frequency of Gm and Inv groups in south-west Germany. Aeta genet. (Basel) 14, 298--308 (1964) Steinberg, A. : Globulin polimorphism in man. Ann. Rev. Genet. 3, 25--52 (1969) Dr. Carlos Manso Institute of Physiological Chemistry Faculty of Medicine Lisbon 4, Portugal

Immunoglobulin allotypes in portugal.

The frequency of several immunoglobulin allotypes has been evaluated in a sample of 419 Portuguese subjects. It was found that the percentage of Gm (1...
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