12, NO. 5, 449-462. Serum protein polymorphism among Tunisian Berbers: haptoglobin, transferrin and group-specific component subtypes, C3 and BF types.
ANNALS OF HUMAN BIOLOGY,
1985, VOL. 12, NO. 5, 4 4 9 - 4 6 2
Serum protein polymorphism among Tunisian Berbers: haptoglobin, transferrin and group-specific component subtypes, C3 and BF types J. CHIBANI Facult6 de Pharmacie et de M6decine Dentaire, Monastir, Tunisia
and G. LEFRANC Laboratoire d'Immunog6n6tique, Montpellier, France and J. CONSTANS Centre d'H6motypologie. C.N.R.S, Toulouse, France Received 26 October 1983; revised 15 March 1985
Summary. The polymorphism of serum proteins (Hp, Tf, Gc, C3 and BF) was determined on 210 samples belonging to Berber groups living in three regions of Tunisia. The gene frequencies obtained among the Berbers are different from the values observed among the other Tunisians. These frequencies differ also within the three Berber communities. The data collected show that the actual Berber community is genetically heterogeneous. Despite the presence of some African admixture, the gene pool of the Berbers from Tunisia shows large homologies with Middle Eastern groups rather than similarities with North African populations.
1. Introduction Among the North African population, the Tunisian and Berber groups living in this region have so far received very limited attention. For this reason, we started to investigate the genetic polymorphism of some Tunisian groups. The immunoglobulins were investigated initially (Gm, Am and Km allotypes) (Lefranc, De Lange, Rivat, Langaney, Lefranc, Ellouze, Sfar, Sfar and Van Loghem 1979, Helal, Lefranc, Hauptmann, Goetz, Tongio, Davrinche, Rivat, Cavelier, Chibani and Chaabani 1981), followed by the determination of other genetic markers such as C3 and BF (Davrinche, Rivat, Rivat-Peran, Helal, Boukef, Lefranc and Lefranc 1981 a), A 7 75 Thr globin (Lefranc, Lefranc, Farhat, Imour, Boukef, Beuzard, Galacteros and Rosa 1981 a), Tf and Gc (Lefranc, Chibani, Helal, Boukef, Seger and Lefranc 1981 b), HLA-BF and C4 Helal, Lefranc, Hauptmann, Goetz, Tongio, Davrinche, Rivat, Cavalier, Chibani and Chaabani 1983). Recently, we extended these genetic investigations to some Berber groups living in three different areas of Tunisia (Chaabani, Helal, van Loghem, Langaney, Ben Ammar, Elgaared, Rivat-Peran and Lefranc 1984a, Chaabani, Martin, Frants and Lefranc 1984 b, Chibani 1983). As in the case of the Basques, the origin of the Berbers is still a matter of controversy (Mourant, Kopec and Domaniewska-Sobczak 1976). Some authors consider them as remnants of the first inhabitants of North Africa. The culture of these people, which developed about 10000 years ago, is known as Capsian, from the Latin name for Gafsa, a city located between the 34th and 35th parallels of latitude in Tunisia (figure). Judging from the existing descendants, these immigrants in the Maghrab from Tunisia to Morocco were moderately light-skinned, and spoke languages of the Afro-Asiatic group. They may be regarded as consisting of protoBerbers, ancestral to the 'pure' Berbers of the Atlas Mountains, and to the Berbers,
J. Chibani et al.
450
8 ° I
9 ° I
10 ° I
MEDITERRANEAN
SEA
11 o I
Bizerte
37 ° _
-37 °
J tI i/~
3 6 ° --
3 5 ° --
x Kesra
-36 ° Takrouna ~ Sousse ~r'kcMonasti r • Kairouan j ~
sI
Sf~/
l "
, eafsa
/ --
-35 °
X G 0
\ Gab~s-~_
34 ° _
34 ° |It ~ ; ~ t ~ i d "~ e . i a n a ~ ~ " '%
I~ledenine~ Guermessa ×
%
33 ° -
Chenini x • Tataouine %
I !
Douiret ×
%
!
!
33 °
I
%
%
I
• Remada
/ I #,
I
32 ° -
32 °
J
I !
,s
s
I
ALGERIA
I I I
/
/ !
t
/
I
31 ° _
I
LIBYA
.31 °
¢
I
I,
~¢'
/
0 I
30 60Km I
I
I I
I
I
I
8 °
9 °
10 °
11 o
Map of Tunisia. Berber's villages are crossed ( x ) . The northern cluster (Jeradou, Takrouna, Kesra) is around the 36th parallel of latitude. The southern cluster (Guermessa, Chenini, Douiret) is located near the 33rd parallel.
Polymorphism amongst Tunisian Berbers
451
now in varying degree 'arabized' in language and culture, of the rest of the Maghrab (Mourant et aL 1976). They probably occupied a larger territory in their past history than their present territories. One group has taken refuge from foreign invaders in hilly regions where access is difficult. This usual behaviour for ancient populations was in general followed by a preservation of the cultural traits and of the language. A consequence of these movements is often a reduction in size of the population, and the presence of genetic drift. Another group of native Berbers must have intermarried with the different invaders (Pheonicians, Greeks, Romans, Negroes, Vandals, Arabs, etc.). It is unlikely that any of these invaders modified to a great extent the racial composition of the population as a whole. The arab invasion of the sixth and seventh centuries A.D. and, later, those of the Banu Hilal and other Bedouin tribes in the l l t h century brought about the conversion of most of the people to Islam and the extensive adoption of the Arabic language. There must have been a substantial incorporation of invaders in the population, but this has tended to be exaggerated (Mourant et al. 1976). For these historical reasons and due to the lack of genetic data on these Berbers, we determined the polymorphism of some serum proteins such as transferrin, groupspecific component or Gc, C3 and Factor B or BF of the complement and the haptoglobin oq and o~2 chains.
2.
Samples and methods The samples were collected from unrelated and healthy Tunisian Berbers from the villages of Kesra, Takrouna and Jeradou in the Central Region of Tunisia, and of Chenini, Douiret and Guermessa in the South (figure). Because of the proximity of some villages, only three main regions were considered: Kesra, Takrouna-Jeradou and then Chenini-Douiret-Guermessa. The inhabitants of these villages are assumed to be 'pure' Berbers or mainly of Berber stock, some of them still being Berber-speaking. However, these groups are affected by a continuous migration of large numbers to the main cities because of economical and educational constraints. Linguistic and social characteristics have been important factors in creating barriers for the separate existence of these communities and in limiting marriages with non-Berbers. A comparative sample was obtained from unrelated young students in the different cities of Gabes, Sfax, Monastir, Souss and Tunis. Agarose gel electrophoresis was used to determine the T f C, B and D phenotypes (Teisberg 1970, Ktihnl and Spielmann 1972). The T f C and Gc subtypes were determined by analytical isoelectrofocusing on polyacrylamide gels in the pH range 4.0-6.5 (Constans and Viau 1977, Constans, Viau, Cleve, Jaeger, Quilici and Pallison 1978a, Constans, Viau, Pison and Langaney 1978b, Constans, Richard and Viau 1978c, Ktihl, Spielmann and Weber 1979, Hoste 1979). C3 and BF typing were performed by high-voltage agarose gel electrophoresis as described by Teisberg (1970). Immunofixation was carried out with specific anti-factor B antibodies (Alper and Johnson 1969). Haptoglobin phenotypes were determined by electrophoresis on starch gel (Smithies 1955) and the haptoglobin subtypes by isoelectric focusing migration on polyacrylamide gel, using ampholyte solution in a pH range 5-7 (Shibata, Constans, Viau and Matsumoto 1982). The gene frequencies were calculated by the maximum likelihood method. The X2 values were estimated according to the Hardy-Weinberg equilibrium hypothesis.
22 22.74
49
47.20
44
39-41
Obs. Exp.
Obs.
Exp.
Obs.
Exp.
Kesra
Douiret + Chenini + Guermessa
Jeradou + Takrouna
115 108-47
244 241.72
Obs. Exp.
Obs. Exp.
C1-C1
32.78
23
23.01
19
27 25.26
69 82.78
130 134-59
C2-C1
6.82
12
2.80
5
6 7.02
23 15.79
21 18-74
C2-C2
0.70
1
0
0
1 1.26
2 2.14
7 6.96
CI-D1
0.29
0
0
0
1 0.70
1 0.82
2 1 "94
C2-DI
Phenotypes
0-00
0
0
0
0 0.02
0 0-01
0 0.05
D1-D1
0
0.00
0"70
0-01
0
0 0
0 0.01
0 0
B-B
1
1.59
2
0 0
3 2.14
0 0
CI-B
TFC2=0.215 X2 =0-452
x 2 = 0- 766 T f c2 = 0" 290
T f B = 0.013 T f cl = 0" 698
T f D1 = O" 006 T f B = 0"006 X2 = 7" 393
75 81
81
T f c2 = 0.193
Tf cl = 0- 794
75
T f c2 = 0- 351 x 2 = 0- 290
T f cl = 0- 632 T f Dj = 0" 017
TFC1=0"714 Tj~'2=0"272 T f D1 =0.007 T f B =0.007 X2=5-975
TfC~=0.774 TfDI=0-011
Gene frequencies
57 57
213 213
404 404
Total
Distribution of the Tf phenotypes and allele frequencies among Tunisians and Berbers.
Total
Tunisian Berbers (present study)
Other Tunisians (Lefranc et al. 1981 b)
Populations
N
Table 1.
b~
4~
Polymorphism amongst Tunisian Berbers
453
3. Results and discussion Transferrin The frequencies of the Tf*C1, Tf*C2 subtypes and of two additional variants are presented in table 1. In the Tunisian samples the Tf*C1 frequency is lower than in Europe (Thymann 1978). The Tf*C1 and Tf*C2 frequencies, 0.70 and 0.29 respectively, among the Berbers living in the Southern region of Tunisia (CheniniDouiret-Guermessa) are significantly different from those found in the rest of the Tunisian population (0.79 and 0.21 respectively) and in the Berber villages of Takrouna-Jeradou (0.79 and 0.19). Likewise, the frequencies at Kesra (0.63 and 0.35) differ significantly from those noted at Takrouna-Jeradou and in the non-Berber people. The presence of Tf*D in Tunisian population, which is evidence of a Negroid contribution in the gene pool, is observed at Kesra. The Tf*B mutant is present at Takrouna-Jeradou and at Guermessa. The presence of the Tf*D and Tf*B alleles among the Berbers might either indicate some admixture or represent rare genes without foreign contribution.
Group-specific component The Gc gene frequencies among the Berbers are presented in table 2. The frequency of the Gc* 1S allele (0.70) obtained at Takrouna-Jeradou is significantly different from those found at Kesra (0.57) and mainly in Douiret and Chenini villages (0.53) as well as among the non-Berber Tunisians (0.53). The frequencies of the Gc*IS and Gc*IF subtypes, 0-53 and 0.21 respectively, are more similar to those observed in Europe (Thymann and Henningsen 1978, Cleve, Patutschnik, Nevo and Wendt 1978), rather than in Africa and North Africa (Constans, Lefevre-Witier, Richard and Jaeger 1980, Constans, Viau, Jaeger and Palisson 1981 a). C3 component o f the complement The frequencies of the C3"S gene are high in all the populations hitherto studied. In Tunisia, they vary between 0.80 and 0.89 among the Berbers (table 3). The C3"S frequency is 0-83 in the non-Berber Tunisians (Davrinche, Rivat, Rivat-Peran, Helal, Boukef, Lefranc and Lefranc 1981 a, Davrinche, Rivat and Rivat-Peran 1981 b,c). The C3*F gene frequencies, 0.15 in the Tunisian population, 0.12 at Chenini-DourietGuermessa and 0.17 at Kesra, are similar to those observed in Europe (0.17-0.21). The value, about 0.07 at Takrouna-Jeradou is closer to the one found in Black Africa (0.02-0.05). The frequencies noted at Takrouna-Jeradou are significantly different from those obtained in non-Berber Tunisians and in the Berber villages from South Tunisia. The combined frequencies of the rare alleles C3*FI and C3"S 0-4 in the samples of Berbers, about 0.02 at Kesra and 0.04 at Takrouna-Jeradou, are higher than those observed in non-Berber Tunisians (0.014) (Davrinche et al. 1981 a,b,c) or in Europe (0" 006) (table 3). Factor B or BF The BF*s gene frequencies at Takrouna-Jeradou and at Chenini-DouiretGuermessa, 0-507 and 0.473 respectively, are significantly different from those observed in the non-Berber Tunisians (0.617) and in Europe (0" 69 to 0.82, except for the Basques 0.56) (Davrinche et al. 1981 b, Kuhnl and Spielmann 1978 c) (table 4). The BF*S frequencies among the Berbers are near to those obtained in Saudi Arabs (Goedde, 1979) and are rather close to those observed in African populations with
Obs. Exp.
1S-1S
Douiret + Chenini + Guermessa
25
23"08
Exp.
36.75
Exp.
Obs.
33
Obs.
21 18.53
Obs. Exp.
Kesra
Jeradou + Takrouna
79 77.16
Obs. Exp.
98 97.54
IS - 1F
18.57
14
19.60
22
13 16.54
49 55.24
92 95.16
3"73
3
2"61
3
4 3"69
I0 9"89
26 23.21
1F-1F
22"28
23
11.90
17
10 11.40
50 47.44
81 78.77
2-1S
Phenotypes
8-96
15
3-17
0
8 5.09
23 16.98
36 38.42
2-1F
5"38
2
0.96
0
1 1.75
3 7.29
16 15-90
2-2
82
82
75
75
57 57
214 214
349 349
Total
G c 1F = 0.215
Gc 2 = 0.256
G c 1F = 0.187
x 2 = 7.494
G c l F = O. 214
x 2 = 2- 862 G c i s = 0" 530
G c 2 =0"113
G c is = 0-700
G c I F = 0.254
x 2 = 2" 924
G c is = 0" 570 G c 2 = 0-176
X2 = 5" 547
Gc is = O . 600 G c 2 = 0" 185
x 2 = 0- 659
G c iF = 0.258
Gene frequencies G c I s = 0" 527 Gc 2 =0.213
Distribution of the Gc phenotypes and of the allele frequencies in Tunisians and Berbers.
Total
Tunisian Berbers (present study)
N
Populations
Other Tunisians (Lefrancetal. 1981b)
Table 2.
4~
N
9 8.05
16
52
52-74
73
71.32
Obs.
Exp.
Obs.
Exp.
N
Douiret + Chenini + Guermessa
Populations
5
0
C3 F 0.210
0. 204 0"30 0.045 0.092
C3 S
0-757
0. 788 0-70
0.951 0.900
508 200
275 359
German (Berlin)
French Normans Basques
Cameroun Saudi Arabian
0
0
0-004 0"008
0.008 --
0.033
C3 rares
1.32
3
4.47
0 0.00
2 1.39
0.31
5 4.34
5 2.71
Gene frequencies
19.37
12 12.87
30 29.76
Obs. Exp.
Kesra
Jeradou + Takrouna
37 40.78
155 153"57
162 161.53
Obs. Exp.
S-S0.4 4 3"33
F-F 7 5.41
S-F 57 59.12
S-S
0
0
0.34
0
0 0.00
0 0.58
0 0.61
F-S0.4
Reference
0
0
0.09
0
0 0.00
0 0-03
0 0.02
S0.4
SO. 4-
0
0
0
0
0 0.00
0 0-02
0 0.03
S0.4
F rare
0
0
0
0
0 0.35
0 0-23
0 0.46
0
0
0
0
0 0.02
0 0.00
0 0.01
92
92
66
66
46 46
204 204
233 233
F rareF - F rare F rare Total Gene frequencies
Goedde et al. 1979
Davrinche et al. 1981 b
c 3 F = 0.068
C3S= 0-880
x2= 0-625
C3 F = 0.120
C3 S°'4 = 0"038 X2 = 0.123
C3S= 0-894
C3 S= 0-804 C3 F - 0-714 C3 Frare= 0.0212 X2 = 0.606
C3 S = 0.868 C3 F = 0.116 C3 S0"4= 0"012 C3 Frare= 0.004 x 2 = 0-363
C3 S = 0.834 C3 F = 0.152 C3 S0"4= 0-008 C3 Frare= 0.006 X2 = 0.545
Geserick, Marth, Schmitzler, Gogochia, Mirvis and Annenkow
0
0
0.00
0
2 1-61
2 1.74
3 2.50
S-F rare
Phenotypes
C3 p h e n o t y p e d i s t r i b u t i o n a n d allele f r e q u e n c i e s in T u n i s i a n s a n d B e r b e r s a n d in o t h e r p o p u l a t i o n s .
Total
Tunisian Berbers (present study)
Other Tunisians Obs. (Davrinche et al. 1981a) Exp.
Populations
T a b l e 3.
4~ t.~
456
J. Chibani et al.
Negroid admixture in their gene pool (table 4). Such an observation might indicate either a Negroid contribution or could be merely due to geographical variations without Black admixture. They, however support the African origins of the Berbers from Tunisia. The frequencies of the rare BF*S0.7 allele (about 0.08) are relatively high and similar to that observed in the non-Berber Tunisians (Davrinche et aL 1981 a). The BF*F1 gene frequencies (about 0.05) are higher than those observed in Tunisia and in Europe, except for the Basques (table 4). One case of deficiency of Factor B associated with decreased levels of C3 was detected in the sample of Douiret. The familial study is now in progress to determine the genetic cause of this abnormality. Haptoglobin
The phenotypes and the gene frequencies are presented in tables 5 and 6. The Hp 1 gene frequency in the total Berber sample is slightly different from the value observed in the Tunisians. It can also be noticed that these Hp 1 frequencies are also different between the Berber villages; the higher value being obtained in the Berber group living in Douiret but the differences in the phenotype distributions and in the allele frequencies are not significant. These gene frequencies fluctuate in the range of the values generally observed among the North African groups but they are different from the data previously published for Saudi Arabians (Goedde et al. 1979) or Lebanese (Lalouel, Loiselet, Lefranc, Chaiban, Chakhachiro, Rivat and Ropartz 1976). The Hp 1 and Hp 2 allele frequencies obtained for the Tunisians and Berbers are not significantly different from the values observed in European groups (Cleve 1966, Fraser, Volkers, Bernini, van Loghem, Meera-Khan and Nijenhuis 1974). Polymorphism o f the haptoglobin peptides: owing to the necessity of a preliminary step of protein purification before the determination of the haptoglobin chains, the sample available for investigation was smaller than the one used for the determination o f the haptoglobin phenotypes (Constans et al. 1981 b). This is particularly true concerning the Tunisian sample (94 individuals) while among 200 Berbers, only 154 sera were examined for Hp chain subtyping. When haptoglobin subtyping was performed, it was found that the Hp 2 gene frequency, was much more affected than the frequency of the Hp 1 allele (Hp IF + Hp is allele frequencies. This observation is compatible with that of a lower haptoglobin serum level among Hp2-1 and Hp2-2 phenotypes (Constans et al. 1981 b). The absence of observed HplF-1F individuals in the Tunisian samples and the excess of observed HplF-1S phenotypes can also be considered as the reason of the elevated X2 value. The difference between observed and expected numbers might be due to an unknown bias in the sampling process for the haptoglobin subtyping more than any disturbance in the distribution of these alleles in the population. In the Tunisian and Berber samples the Hp is allele is more frequent than Hp 1F. It can be seen that the genetic difference between Berbers and Tunisians is mostly due to the Hp 2 allele frequencies, whereas between the Berber communities, the group living in Kesra differs from the two others by showing the highest Hp 1F allele frequency obtained. The Hp is and Hp 2 allele frequencies when considered simultaneously are more informative than the HplS/Hp I ratio, as being previously discussed (Constans et al. 1978 c). In this study, the frequencies show a very close similarity with those obtained for populations from Algeria (Tuareg), from Djibouti (Afar and Issa) and from South Yemen. The Berber groups and the Tunisians seem to be weakly influenced by African admixture, which is generally characterized by a higher Hp 2 allele frequency and by the
N
512 200
264
161 458
80 246
French Normans Basques
Italian
Mali Touareg Dogons
Nigerian Saudi Arabian
BFS
0' 275 0.474
0- 577 0. 300
0.715
0.742 0. 562
0" 799
N
482
11.52
5.67
6
6-59
8
4 5"05
18 17.33
41 38"27
S-S0.7
0" 668 0' 447
0' 344 0" 639
0-246
0' 228 0- 305
0" 179
BFF
0.013 0.059
0.021 0.014
0.018
0.008 0.007
--
BFS0.7
Gene frequencies
27-41
16"30
Exp.
15
9.24
26-85
20
11
22
20
5 5-68
31 26"22
44 29"68
F-F
19 20"21
Obs.
19.50
Exp.
German (Hessen)
Populations
Douiret + Chenini + Guermessa
22
Kesra
19 17"96
61 74"93
104 130-23
154 142"91
61 53'52
S-F
S-S
0.49
1
0.56
0
0 0-36
1 1.40
2 2-56
S0"7 -S0"7
0- 17
0
0.27
0
0 0.11
0 0'54
0 0.13
F 1 F1
73
73
76
76
57 57
206 206
375 375
Total Gene frequencies
BJ6el = 0 " 0 5 9
BJF=0.349
B f f 1 = 0" 048
BfSO.7 = 0" 082
X2=3.911
BJF=0.397
BFS=0.473
X2 = 1-834
BFS°'7=0.085
BJS=0.507
BJF=0.316 BFS0"7=0.079 Bf I =0"044 X2= 0.433
BfS=0.561
BfSO'7=0"083
X2= 6.505
B/F=0.357
BJF1=0.051
BfS=0.509
Bfs =0.617 BIF =0"281 BFS9"7=0.083 BJFI=0.019 X2= 13.587
Davrinche 1981
Larsen, Salimonu, Gow and Marshall 1981 Goede et al. 1979
0-056 0-046 0"025 0-020
Malavasi, Carbonara, Olivetti, Migone, Curtoni, Boschis and Milanese 1980
0-58
0
0.77
2
0 0.39
1 1.73
1 1"16
S0-7 -F1
0.026
Kiihnl 1978
Reference
2.78
4
3.14
5
2 1.58
11 7"49
3 3.94
F-FI
Davrinche et al. 1981 a
4.77
4
4.53
4
5 2.84
13 12'13
16 17.44
F-S0"7
0-020 0.125
BFFI
3.31
3
4.56
3
3 2'81
9 10-70
10 8"64
S-F1
Phenotypes
D i s t r i b u t i o n o f the BF p h e n o t y p e s a n d o f the allele f r e q u e n c i e s in T u n i s i a n s , B e r b e r s a n d in o t h e r p o p u l a t i o n s .
Obs.
Obs. Exp.
Jeradou + Takrouna
Obs. Exp.
Total
Tunisian Berbers (present study)
Other Tunisians Obs. (Davrinche et al. 1981b) Exp.
Populations
T a b l e 4.
.-...I
~z
4.
q"
50 51
21 23- 3
Douiret, Chenini, Guermessa Obs. Exp.
Obs. Exp.
16 14.9
Jeradou and Takrouna Obs. Exp.
Total
13 13- 3
79 75.7
Hp 1-1
102 100
41 36.4
33 35.2
28 27.5
184 190.5
Hp 2-1
Haptoglobin phenotypes
48 49
12 14.3
22 20.9
14 14.2
123 119.8
Hp 2-2
200
74
71
55
386
N
0" 505
0. 561
0"458
0.491
0.443
Hp I
0- 495
0-439
0-542
0" 509
0.557
Hp 2
Gene frequencies
Distribution of the haptoglobin phenotypes and of the Hp 1 and Hp 2 alleles in the different samples investigated.
Kesra Obs. Exp.
Berber Communities
Other Tunisians Obs. Exp.
Populations
Table 5.
X2
0.040
0.567
0. 143
0.009
0.221
(l.d.f.)
Oo
4 5" 39 5 5.03 9 6- 73 14 12.56 . . -. 6 7.85 -. . . 39
14 9- 83 5 5" 15 28 22' 34 19 23.4 0 0- 45 1 0' 47 26 26.6 1 1' 06 0 0" 01 94 0.223 0.234 0. 532 0" 011 4.031
Gene frequencies Hp 1v H p Is Hp 2Fs H p 2ss X2 (1 .d.f.)
0- 192 0" 359 0- 449 -1 '285
1 1-44
Kesra
0 4.69
Tunisians
1F-1F Obs. Exp. 1F-IS Obs. Exp. 1S-IS Obs. Exp. 2FS-1F Obs. Exp. 2FS-1S Obs. Exp. 2SS-1F Obs. Exp. 2SS-1S Obs. Exp. 2FS-2FS Obs. Exp. 2FS-2SS Obs. Exp. 2SS-2SS Obs. Exp. Total number . .
.
.
. .
0-243 0.284 0.473 ~ 0.30J
37
--
8 8.28
--
11 9.93
8 8" 51
2 2"98
6 5' 11
2 2.19
Jeradou
. .
.
.
. .
0.244 0.288 0. 468 -1 "076
. . 78
_ .
16 17.08
.
. .
21 21- 06
20 17" 78
8 6"49
8 10' 96
5 4"63
Douiret
Berber communities
Distribution of the Hpc~ and Hpc~2 subtypes and of the four alleles in the Tunisians and Berber groups.
Haptoglobin subtype distributions
Table 6.
0.231 0- 305 0.464 _ 1-242
154
_
30 33.20
46 43.64
37 32" 96
15 14.34
18 21-67
8 8" 19
Total
4~
"~ e~
~'
U~"
~"
460
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presence o f the Hp0 and Hp2-1M phenotypes (Sutton, Neel, Binson and Zuelzer, 1956, Bong-Sop and Bearn 1964). In comparison to the polymorphism of the Hp a chains, a considerably small variability of the Hp o~ 2 chains was detected. The Hp 2Fs mutant is predominantly present in the Berber samples while two individuals have been found to be heterozygous of the rare Hp ass mutant in the Tunisians. The presence of the Hp 2ss allele, previously observed with a high frequency in North African group and in tribes from North Yemen (Constans et al. 1978 c) was interpreted as common t o North African and Mediterranean populations. This observation is not confirmed by this investigation. A different hypothesis is to consider that the Hp 2ss allele in the Berbers might have been lost in the past by random events accentuated by a genetic drift.
Conclusions It is difficult to account for the origin of the Berbers from Tunisia. The genetic markers under study allow us to define their gene pool as a mixture of Mediterranean genes and of a fair proportion of African ones. The BF*S frequencies are close to those observed in Black Africa whereas the Gc*l F and Gc*l S subtype frequencies are typical of European populations. Consequently, the very low frequency of the Tf*D1 variant, and in contrast, the high BF*S gene frequencies might reveal either limited exchanges between Berbers and invaders come from Black-Africa, or the presence of a Negroid ancestry, or originality without admixture of the gene pool of the Berbers. These groups may have preserved not only their customs and culture but also their genetic pool. Moreover, the distribution of the protein gene frequencies and of other genetical markers (Chaabani et al. 1984 a) seem to indicate that the Tunisian Berbers are heterogeneous. Berbers from Takrouna-Jeradou show significant differences from those living in Kesra and in the South when the T f and Gc gene frequencies are considered. The C3 gene frequencies are also significantly different at TakrounaJeradou and in the South. These variations might be explained either by different origins for these groups of Berbers or by variable admixtures. They might also be explained by a common origin followed by differentiation due to founder effect or genetic drift. Acknowledgements We thank Drs M . P . Lefranc, J. Seger, A. Sevin, C. Davrinche and C. Rivat for stimulating discussions. We are indebted to Dr L. Y. Lai for his interest in this paper. We are grateful to Mrs N. Ben Khalifa, A. Ben Salem, M. Ben Salah and C. Abderrazak for skilful technical assistance. We wish to thank also the people responsible for the dispensaries of the villages for providing us with the blood samples.
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Znsammenfassung. Die Polymorphismen des Serumproteins (Hp, Tf, Gc, C3 und Bf) wurden an 210 Proben bestimmt, die yon Berbergruppen aus drei Regionen yon Tunesien stammen. Die Genfrequenzen der Berber sind unterschiedlich von den Werten der anderen Tunesier. Die Frequenzen unterscheiden sich auch zwischen den drei Berbergemeinschaften. Die gesammelten Daten zeigen, dab die heutige Berbergemeinschaft genetisch heterogen ist. Trotz einiger afrikanischer Beimischung zeigt der Genpool der Berber yon Tunesien eher groBe Homologien mit Gruppen des nahen Ostens als .~hnlichkeiten mit nordafrikanischen BevOlkerungen. R6sum6. Le polymorphisme de quelques prot6ines s&iques (haptoglobine, transferrine, Group Specific component, fraction C3 du compl6ment et facteur BE) a 6t6 6tudi6 sur deux cent dix 6chantillons provenant d'une enqu&e r6alis6e darts trois villages Berb~res de Tunisie. Les fr6quences g6niques obtenues darts les groupes Berb~res sont diff&entes de celles observ6es darts la population Tunisienne de comparaison. Les fr6quences g6niques diff&ent aussi entre les groupes Berb&es eux-mSmes. L'ensemble de r6sultats obtenus montrent que la communaut6 Berb~re actuelle est g6n6tiquement h6t6rog~ne. Malgr6 la trace d'un m6tissage avec des groupes appartenant A l'Afrique centrale, le g6nome des Berb6res de Tunisie montre de larges analogies de ceux-ci avec les populations du Moyen-Orient plut6t que des similitudes avec les populations Nord-Africaines.
