M. T. AKBARI,¹ S. S. PAPIHA,² D. F. ROBERTS,³ AND D. D. FARHUD⁴

Received May 18, 1984; revised June 13, 1985.

American Journal of Human Genetics, 38:84-98, 1986

SUMMARY

From some 500 members of Christian communities in Iran (Armenians and Assyrians from six localities), blood specimens were obtained and examined for a number of blood group, red cell enzyme, and serum protein systems. The results indicate the relatively closed nature of the Christian community as a whole but that moderate differentiation has already occurred among the local groups. One factor in this diversification process that can be distinguished is the effect of urbanization in Tehran, but otherwise it seems to be largely random.

INTRODUCTION

Among the present-day ethnic composition of Iran, two Christian populations-the Armenians and the Assyrians-represent distinct religious minorities. These groups are widespread, with concentrations in various regions both in Iran and in the neighboring countries. Historically, there were movements of the Christian population under the pressure of Muslim and other invading groups, but due to their religious and cultural traditions, there has been little intermixture with other populations.

Genetic knowledge of the Iranian Armenians and Assyrians is limited to a few blood group systems [1-3]. Some of the systems studied demonstrated clear genetic differences between the Christians and the rest of the population of Iran. The known historical movement and settlement of these Christian groups in Iran provides an excellent background against which to study the genetic differentiation among their various regional subgroups. The present investigation of Iranian Christians therefore extends genetic information to include some of the systems that have not yet been studied and also examines the genetic differentiation and structure of the populations.

Armenians

The Armenians once occupied a large part of the area now known as Turkey, formerly the seat of the Hittite Empire. Their spread and contact with European civilization was promoted with the conquests of Alexander the Great when the Armenians became part of the newly formed Macedonian Empire. The Armenians accepted Christianity early, in 301 A.D. An influx of Armenians to Iran occurred in 1604 when Shah Abbas brought them as Christian captives from Jolfa (now in Soviet Armenia). Instead of being treated as slaves, they were encouraged to develop trade between east and west in Isfahan (then capital of Iran), which later intensified with the change of the capital to Tehran. According to the 1970 census of Iran, the Armenians were estimated at 200,000, living in four regions-Tehran, Isfahan, Tabriz, and Uromia.

Assyrians

The Assyrians are a group of Christians, also known as Nestorians, with a long history in the Middle East. From historical and archeological evidence, it is thought that their ancestors formed part of the Mesopotamian civilization. In the early part of this century, the Assyrians had to move into Iraq, where they were promised safety during World War I. A few years later, at the end of the war, most of them returned to Iran; some returned to Uromia, a rural settlement, their home area in Iran, but many went direct to Tehran where they formed their own urban community. In spite of these movements, the Assyrians kept themselves distinct socially.

Methods

From a total of 297 Armenians, blood samples were collected from Uromia, Tabriz, Isfahan, and Tehran (fig. 1). For Assyrians, 225 specimens were collected from Tehran and Uromia. Subjects were randomly selected, except that any close relatives were excluded. The blood grouping was performed in Tehran, and the plasma and red cell lysate samples were stored at -30°C until transported in dry ice to the Department of Human Genetics, Newcastle upon Tyne, where the electrophoretic studies were performed.

All specimens were tested with the following antisera: A, A₁, B, C, C^w, c, D, E, e, S, s, P₁, Le^a, Lu^a, Lu^b, K, k, Fy^a, Fy^b, and Jk^a. Red cell enzymes adenosine deaminase (ADA), esterase D (ESD), phosphoglucomutase I (PGM₁), adenylate kinase (AK), 6-phosphogluconate dehydrogenase (6PGD), and acid phosphatase (AP) were examined according to the methods listed in [4]. The serum protein complement component (C3), haptoglobin (Hp), and transferrin (Tf) were examined by the methods standard in this laboratory [5]. The gene frequencies were calculated by maximum likelihood and gene counting methods. The F-statistics of Wright were calculated from the diallelic loci for which the heterozygote was discernible. F_IT estimates were based on the heterozygote deficit or excess in the total population; F_IS the mean of the estimate from the heterozygote excess over subpopulations; and F_ST from F_IT and F_1S.

RESULTS

The phenotype frequencies in Armenians from Uromia, Tabriz, Tehran, and Isfahan, and Assyrians from Tehran and Uromia are given in table I and gene frequencies in table 2. In no system was there any deviation from Hardy-Weinberg equilibrium.

MAP OF IRAN SHOWING THE SITE OF SAMPLE COLLECTION

Fig 1.ùGeographical Location of Samples

Blood Groups

For the ABO system, the A gene frequency ranges in Armenians from 29% to 40% and in Assyrians from 26% to 33%. In neither Assyrians nor Armenians is there any regional genetic heterogeneity (X² = 8.69, d.f. = 9, NS, and X² = 6.41, d.f. = 3, NS, respectively), and there is no interethnic heterogeneity (X² = 6.47, d.f. = 4, NS). The slightly lower frequencies of the A_I gene in Armenians and Assyrians of Tehran (29% and 27%, respectively) by comparison with those in the original rural settlements of Uromia (differences are at the expense of O genes since the B gene frequency varies little) suggests some intermixing in Tehran with the local urban communities in whom the A gene frequency is lower (22%).

Table 1

Distribution of blood group antigens, serum proteins, and red cell enzymes among different regional groups of Armenian and Assyrian Christians in Iran (x² tests deviation from Hardy-Weinberg equilibrium.