[Mitochondrial DNA polymorphism in populations of the Caspian region and southeastern Europe]

Abstract

Mitochondrial DNA (mtDNA) restriction polymorphism was examined in Turkmens, Eastern Iranians, and Ukrainians. The gene pools of all populations studied were characterized by the presence of European mtDNA lineages. Mongoloid component observed in Turkmen and Iranian populations with the frequencies of about 20% was represented by groups C, D, and E/G in Turkmens, and by M*, D, A, and B in Iranians. The relative positions of the populations studied, of populations from the Caucasus, Western Iran, and Russian populations from the Krasnodar krai and Belgorod oblast in the space of principal components revealed a geographically specific pattern of the population clustering. The data on mtDNA polymorphism indicated pronounced differentiation of Eastern and Western Iranians. The latter were characterized by a mtDNA group composition similar to that in Eastern Slavs. The historical role of the Caspian populations in the formation of the population of Southeastern Europe is discussed.

Full text

1022-7954/02/3804- $27.00 © 2002
MAIK “Nauka
/Interperiodica”
0434
Russian Journal of Genetics, Vol. 38, No. 4, 2002, pp. 434–438. Translated from Genetika, Vol. 38, No. 4, 2002, pp. 534–538.
Original Russian Text Copyright © 2002 by Malyarchuk, Derenko, Denisova, Nassiri, Rogaev.
INTRODUCTION
Since ancient times, the population inhabiting west-
ern regions of the Central Asia and Iranian upland
played the key role in the peopling of East European
territories. It is suggested that one of the routes of the
Homo sapiens sapiens
penetration to Europe passed
though the Caspian regions. Later, during the
Mesolithic, the Caspian regions and refuges at the south
of Eastern Europe were the starting points for recoloni-
zation of the European territories [1, 2]. During the
Bronze Age, cattle-breeder tribes from the Caspian
regions settled in the European territories [3, 4].
According to paleoanthropological data, during Scyth-
ian time (the early Iron Age) Eastern European steppes
were the territories of activity of tribes belonging to the
Scythian confederation [4]. Apparently, exactly Iranian
tribes played an important role at the first stages of
Scythian ethnogeny. Later Scythians spread over wide
territories of Europe, Central Asia, and Southern Sibe-
ria, accumulating many ethnic components. The Ira-
nian substrate also played a significant part in the for-
mation of Eastern Slavs, specifically, Ukrainians and
southern ethnic territorial groups of Russians. Accord-
ing to anthropological and archaeological data, in early
Middle Ages Iranian-Slavic symbiosis (Chernya-
khovskaya culture) was a typical feature of the popula-
tion of East European steppes [5, 6]. In view of this, it
is likely that Iranian, or Iranianized tribes could have
been affiliated with Eastern Slavs.
The data on biochemical and molecular genetics
generally agree with the ideas of anthropologists,
archaeologists, and linguists considered above. Gene
mapping analysis of classical markers showed that the
distribution of alleles of protein loci reflected several
trends of variability that can be interpreted on the his-
torical basis. For instance, according to the data of Cav-
alli-Sforza
et al.
[7], the distribution of the third princi-
pal component in the populations of Europe suggests
that during the Bronze Age the populations migrated
from the Caspian regions to the east of Europe. Based
on the polymorphism of autosomal DNA loci, analo-
gous variability trend was also described for the second
principal component of European population gene pool
[8]. Analyses of biallelic and microsatellite Y-chromo-
somal loci variability revealed more evident similarity
between the gene pools of East European and West
Asian populations. Examination of Y-chromosomal
polymorphism pointed to the existence of distinct dif-
ferentiation between the populations of Western and
Eastern Europe. At the same time, the populations of
Eastern Europe (specifically, Slavic populations,
including Western Slavs) demonstrated substantial sim-
ilarity with the populations of Western Asia, and Ira-
nian populations in particular, in respect of the distribu-
tion of Y-chromosomal markers [9]. Detailed examina-
tion of the populations of Southwestern Asia showed
that distribution of Y-chromosomal type group, HG3,
marked with the SRY-1532-A variant, favored the
hypothesis that during the Bronze Age cattle-breeder
tribes of Western Asia have spread in various directions,
namely, to India, Central Asia, Siberia, and Eastern
Europe [10]. Maximum HG3 frequencies are typical of
the populations of Eastern Iran and Western Asia [10],
Mitochondrial DNA Polymorphism in Populations
of the Caspian Region and Southeastern Europe
B. A. Malyarchuk
1
, M. V. Derenko
1
, G. A. Denisova
1
, M. R. Nassiri
2
, and E. I. Rogaev
3
1
Institute of Biological Problems of the North, Russian Academy of Sciences, Magadan, 685000 Russia;
fax: (41322)34-463; e-mail: ibpn@online.magadan.su
2
Meshhed University, Meshhed, Iran
3
National Research Center of Mental Health, Russian Academy of Medical Sciences, Moscow, 113152 Russia
Received June 27, 2001
Abstract
—Mitochondrial DNA (mtDNA) restriction polymorphism was examined in Turkmens, Eastern Ira-
nians, and Ukrainians. The gene pools of all populations studied were characterized by the presence of Euro-
pean mtDNA lineages. Mongoloid component observed in Turkmen and Iranian populations with the frequen-
cies of about 20% was represented by groups C, D, and E/G in Turkmens, and by M*, D, A, and B in Iranians.
The relative positions of the populations studied, of populations from the Caucasus, Western Iran, and Russian
populations from the Krasnodar krai and Belgorod oblast in the space of principal components revealed a geo-
graphically specific pattern of the population clustering. The data on mtDNA polymorphism indicated pro-
nounced differentiation of Eastern and Western Iranians. The latter were characterized by a mtDNA group com-
position similar to that in Eastern Slavs. The historical role of the Caspian populations in the formation of the
population of Southeastern Europe is discussed.
HUMAN
GENETICS

RUSSIAN JOURNAL OF GENETICS
Vol. 38
No. 4
2002
MITOCHONDRIAL DNA POLYMORPHISM IN POPULATIONS 435
Slavic populations of Europe [11], and the populations
of Altai-Sayan region of Siberia [12].
The studies of variability of another polymorphic
system, maternally inherited mitochondrial DNA
(mtDNA), can also provide useful information for the
investigations of the genetic history of the populations
of the Caspian regions and adjacent territories. These
populations, however, still remain unexplored in
respect of mtDNA polymorphism. Here we present the
data on mtDNA polymorphism in the populations of
Iran, Turkmenistan, Southern Russia and Ukraine. The
data on mtDNA variability obtained were compared to
those for adjacent territories by use of phylogeographic
approach. Application of the given method shed the
light on the peculiarities of the distribution of mtDNA
markers in the populations studied.
MATERIALS AND METHODS
Total DNA from biological tissues (blood and hair
bulbs) was extracted by use of standard methods. The
sample of Iranians (Persians;
n
= 25) from the western
regions of Iran (province Khorasan) was studied. On
the northeast the province is bordered by Turkmenistan.
The sample of Turkmens (
n
= 26) was mostly com-
prised of Turkmens-Tekke (the cities of Ashgabat and
Chardzhou). The sample of Ukrainians (
n
= 36) was
formed from the inhabitants of Magadan and Nikolaev
oblast, originating from different parts of the Ukraine.
According to the questionnaire data, 11 of these were of
eastern Ukrainian origin, 8 persons originated from
western, and 10, from southern Ukraine.
Screening of polymorphic sites, determining the
main groups of mtDNA types distributed in the popula-
tions of Eurasia, was performed with the help of restric-
tion analysis of mtDNA fragments amplified in poly-
merase chain reaction (Table 1). Restriction fragments
were fractionated in 8% polyacrylamide gels. The DNA
fragments were detected by staining with ethidium bro-
mide with subsequent visualization in UV light.
Polymorphism was scored by the presence (+) or
absence (–) of the restriction endonuclease recognition
sites. The mtDNA types were identified in accordance
with the classification of mtDNA type groups in the
populations of Eurasia [13, 15]. Interpopulation differ-
ences relative to the frequencies of mtDNA type groups
were estimated using factor analysis (STATISTICA,
v. 5.0). Euclidean distances between the populations
(based on the data on the frequencies of mtDNA type
groups) were calculated using cluster analysis (tree
clustering; STATISTICA,v. 5.0). For comparative anal-
ysis the data on mtDNA polymorphism in Iranians
(Western Iran;
n
= 101), Azerbaijanians (
n
= 48), Arme-
nians (
n
= 191) [14], Adygeians (
n
= 50) [13], and Rus-
sians from Krasnodar krai (
n
= 49) and Belgorod oblast
(
n
= 69) [17] were used.
RESULTS AND DISCUSSION
Table 2 demonstrates the results of the screening for
polymorphic variants determining the main groups of
Eurasian mtDNA types in the populations of Iranians,
Turkmens, and Ukrainians examined. The search for
European (H, V, HV*, J, T, U, K, I, W, and X) and Mon-
goloid (M*, C, D, E, G, A, B, and F) markers was per-
formed. For comparison, the data on the frequencies of
mtDNA groups in the populations of Western Iran (Ira-
nians), Transcaucasia (Azerbaijanians and Armenians),
Northern Caucasus (Adygeians), and also in the popu-
lations of Russians from Krasnodar krai and Belgorod
oblast are presented. Nearly all populations were char-
acterized by the presence of a substantial European
component, represented by the corresponding mtDNA
types. Low frequencies (from 0.52 to 6%) of the Mon-
goloid component were observed in Russians from Bel-
gorod oblast, Adygeians, Armenians, and Azerbaijan-
ians. These mtDNA types mostly belonged to group C.
Among the populations studied, the most pronounced
Mongoloid component with similar frequencies of 20
and 19.2% was revealed in Eastern Iranians and Turk-
Table 1.
Polymorphic restriction variants determining
the groups of mtDNA types in the populations of Eurasia
mtDNA
group
Group-specific restriction variants
H –14766
Mse
I, –7025
Alu
I
V –14766
Mse
I, +15904
Mse
I, –16297
Mse
I,
–4577
Nla
III
HV* –14766
Mse
I
U +12308
Hin
fI
K +12308
Hin
fI, –9052
Hae
II, +10394
Dde
I
J –13704
Bst
NI, +10394
Dde
I
T +13366
Bam
HI, +15606
Alu
I
I –4529
Hae
II, +8249
Ava
II, +16389
Bam
HI,
+10032
Alu
I
W +8249
Ava
II, –8994
Hae
III
X –14465
Acc
I
M: +10394
Dde
I, +10397
Alu
I
C +10394
Dde
I, +10397
Alu
I, –13259
Hinc
II/+13262
Alu
I
D +10394
Dde
I, +10397
Alu
I, –5176
Alu
I
E +10394
Dde
I, +10397
Alu
I, –7598
Hha
I
G +10394
Dde
I, +10397
Alu
I, +4830
Hae
II/+4831
Hha
I
A +663
Hae
III
B 9-bp deletion
F –12406
Hpa
I/
Hin
cII
Note: Groups of mtDNA types were denoted according to the clas-
sification suggested in [13–15]. Positions of polymorphic
restriction sites are indicated relative to the Cambridge Ref-
erence Sequence of human mtDNA [16].

436
RUSSIAN JOURNAL OF GENETICS
Vol. 38
No. 4
2002
MALYARCHUK
et al
.
mens. The structure of the Mongoloid component in these
populations was somewhat different: mtDNA found in
Turkmens, was from group M (C, D, E/G), and in Iranians,
from M (M*, D), A and B. Turkmens had an unusual
mtDNA type marked by polymorphic variants determin-
ing two mtDNA groups, E (–7598
Hha
I) and
G (+4830
Hae
II/+4831
Hha
I). According to the litera-
ture data, these mtDNA types were never described in
human populations before. However, we detected low
frequencies of E/G mtDNA types among indigenous
populations of Southern Siberia (Derenko
et al.
, unpub-
lished results).
As follows from Table 2, different Iranian popula-
tions display substantial genetic differences, mostly
resulting from differences in the frequencies of groups
H, V, and the Mongoloid component [14]. The popula-
tion of Western Iranians was characterized by a typical
European gene pool composition accompanied by the
complete absence of the Mongoloid component. Note
that the data on Y-chromosomal polymorphism also
point to substantial differentiation of the populations of
Western and Eastern Iran [10]. The observed westward
decline of the frequency of the Mongoloid component
in the gene pools of the Central Asian populations from
60% in Kyrgyzes, Kazakhs, and Uigurs [18] to 20% in
Turkmens and Eastern Iranians is most likely associ-
ated with the processes of settling of the Turkic tribes.
These tribes were initially formed in the Central Asia
among the mixed European–Mongoloid forms [4]. The
data on genetic differentiation of Iranian populations do
not conflict with historical data, because it is known
that only central and eastern parts of Iran were included
into the ethnic territories of Persians, but the western
and southeastern parts of Iran since ancient times were
inhabited by the populations of another origin (Azer-
baijanians, Kurds, Lurs, Balochi, etc.) [19]. For these
reasons, the revealed differences in the structure of
mtDNA types in Iranians can be explained not only by
the presence of the Mongoloid component in Eastern
Iranians, but also by interethnic differences in the struc-
ture of the European component in Western and Eastern
Iranians. This proposal, however, requires detailed
examination of mtDNA variability in different ethnic
territorial groups of Iran.
The figure illustrates the distribution of the exam-
ined populations in the space of the principal compo-
nents. Factor analysis revealed two groups of related
populations. The first group is comprised of Armenians
and Azerbaijanians (Adygeians are located somewhat
apart from them), while the second group is represented
Table 2.
Distribution (in %) of mtDNA type groups among the populations of Southeastern Europe, Caucasus, and the Cas-
pian region
mtDNA
group
Population
Russians
(Krasnodar)
1
Russians
(Belgorod)
1
Ukrainians
Western
Iranians
2
Eastern
Iranians
Turkmens
Azerbai-
janians
2
Arme-
nians
2
Adyge-
ians
3
H 38.78 37.68 41.7 43.56 0 19.23 29.17 30.36 30.0
V 8.16 7.25 5.6 7.92 0 3.85 4.17 0 0
HV* 4.08 2.9 0 1.98 8.0 7.69 4.17 7.33 0
J 18.37 11.59 8.3 14.85 8.0 7.69 4.17 8.38 4.0
T 12.24 8.69 8.3 8.91 16.0 15.38 16.67 11.52 14.0
U 10.2 18.84 16.7 8.91 24.0 3.85 16.67 20.94 32.0
K 0 1.45 8.3 6.93 4.0 0 2.08 7.33 2.0
W 0 1.45 2.8 2.97 4.0 7.69 4.17 1.05 2.0
I 2.04 4.35 0 2.97 4.0 0 2.08 1.57 0
X 0 1.45 2.8 0.99 0 0 4.17 2.62 0
M* 0 0 0 0 4.0 0 0 0 0
C 0 1.45 0 0 0 7.69 4.17 0 6.0
D 0 0 0 0 4.0 7.69 0 0 0
E/G 0 0 0 0 0 3.85 0 0 0
A 0 0 0 0 4..0 0 0 0 0
B 0 0 0 0 8.0 0 0 0.52 0
? 6.13 2.9 5.6 0 12.0 15.38 8.33 8.38 10.0
Note: The data are cited from:
1
[17];
2
[14];
3
[13]. The sign ? denotes mtDNA types unidentified by restriction endonuclease analysis.

RUSSIAN JOURNAL OF GENETICS
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No. 4
2002
MITOCHONDRIAL DNA POLYMORPHISM IN POPULATIONS 437
by Eastern Slavic populations. Interestingly, Western
Iranians are located in close proximity of Eastern
Slavic populations. The populations of Eastern Iranians
and Turkmens are most distant from each other as well
as from other population groups. Table 3 presents the
data on Euclidean distances calculated from the data on
the frequencies of mtDNA groups in the populations
examined. Quantitative estimates of the differences
between the population gene pools obtained also point
to genetic differentiation of these populations. Minimal
differences were observed between the populations of
Western Iranians, Russians, and Ukrainians, on the one
hand, and between Caucasian populations, on the other.
The genetic similarity between Eastern Slavs and
Western Iranians described in the present study
deserves special interest. A more detailed examination
of the Russian population from the southern regions of
European Russia along with the examination of other
populations of the Caspian region would probably pro-
vide identification of the desired Iranian component
involved into ethnogeny of Eastern Slavs.
ACKNOWLEDGMENTS
We thank the Corresponding Member of the Russian
Academy of Sciences I. A. Zakharov (Vavilov Institute
of General Genetics, Russian Academy of Sciences) for
his help in this study.
This work was supported in part by the Russian Foun-
dation for Basic Research (grants no. 00-06-80448 and
99-06-80430) and the Russian State Program “Fron-
tiers in Genetics” (grant no. 99-04-30).
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Euclidean distances between populations of southern Eastern Europe, the Caucasus, and Caspian region based on
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Population 123456789
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0 0.13 0.17 0.12 0.46 0.29 0.21 0.21 0.30
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