M Asghar, N Achoubi, S Meitei, K Meitei, B Murry, M Sachdeva, K Saraswathy
endogamous populations, haptoglobin, transient polymorphism
M Asghar, N Achoubi, S Meitei, K Meitei, B Murry, M Sachdeva, K Saraswathy. Haptoglobin polymorphism among three populations of Manipur, India: a critical analysis. The Internet Journal of Biological Anthropology. 2008 Volume 3 Number 2.
Haptogloin is a plasma protein that binds free hemoglobin, thereby inhibiting hemoglobin induced oxidative damage. The distribution of haptoglobin alleles varies according to the geographical location and ethnicity. The present study is carried out to study the frequency distribution of haptoglobin in three endogamous populations of Manipur, India. Serum was separated from blood samples collected from 335 Muslims, 262 Meitei Brahmins and 121 Kabuis.
Haptoglobin is a plasma protein that binds free hemoglobin, thereby inhibiting hemoglobin-induced oxidative damage. During intravascular hemolysis, free hemoglobin in the circulation passes through the glomerular filter and renal damage may occur 1 . The binding of HP with HB prevents both iron loss and kidney damage 1 . HP was first detected by Polonovski and Jayle 2 in serum. Smithies 3 identified three major variants of Haptoglobin in humans using starch gel electrophoresis. These three phenotypes are determined by two co-dominant alleles
The distribution of haptoglobin alleles varies according to the geographical location. An increasing trend of
In the last five decades a large number of studies have been conducted on the distribution of haptoglobin polymorphism from various populations throughout the world. Various authors have summarized these frequency distributions in their respective times 10, 11, 12 . In Indian subcontinent, Bhasin and Walter 13 had compiled almost all the published frequency reports up to 1990. The present study aims at studying the frequency distribution of this marker in three populations inhabiting the Manipur state of India. There are very few reported studies available on haptoglobin in this malarial endemic region. The three population groups studied are Kabui, (a tribe), Meitei Brahmins, (a caste group) and Muslim, (a religious group). All the three populations inhabit the plain regions of Manipur and follow strict endogamy thereby maintaining their own gene pools.
Materials and Methods
Blood samples were collected from 335 Muslims, 262 Meitei Brahmins and 131 Kabuis. Two to three drops of blood were collected in EDTA coated micro-centrifuge tubes (1.5ml) by finger pricking after taking due informed written consent. Plasma was separated by centrifuging the tubes on the same day. The separated plasma was used for genotyping by polyacrylamide disc gel electrophoresis 14 .
Allele frequencies were calculated by gene counting method. Heterozygosities were obtained using the software POPGENE 15 . Hardy-Weinberg equilibrium was calculated using chi-square goodness of fit test. Inbreeding co-efficient was calculated following Sewall Wright formula.
The Nei 16 mean heterozygosity was calculated for all the populations using POPGENE. Heterozygosity is found to be comparatively very low (lower than 0.5) in all the three populations, Meitei Brahmins being the highest with 0.274 followed by Muslims and Kabuis (0.151 and 0.141, respectively). The inbreeding co-efficient was found to be highest among Muslims with 0.149 followed by Meitei Brahmins and Kabuis (0.084 and 0.030, respectively)
Muslims in Manipur are believed to have migrated from Assam and Bengal in around 1600 AD and started to settle there after marrying with the Meitei women 17 . The present data was compared with Muslims of Assam, Bangladesh and West Bengal and also with Meiteis of Manipur which had been reported two decades before to see the changes in the allele frequency, if any. In all the cases except with West Bengal (WB) Muslims (p=0.067) 18 , it shows significant differences with Assam Muslims (p= 0.000) 19 , with Bengali Muslims (p = 0.003) 20 ; with Calcutta Muslims (p= 0.006) 21 and with Meiteis (p= 0.000) 22 .
When we compare the present data of Meitei Brahmins with earlier reported data in the same population and also with Meitei population of the same state, statistically significant differences are observed; p-value being 0.000 when comparing between Meitei Brahmins of present study and earlier reported data 22 , p= 0.001 between Meiteis 22 . The same is observed in case of Kabuis also. In comparison with the earlier Meitei data, Kabuis show significant difference (p= 0.000) 22 .
Even though the frequency distribution of HP follows the trend as observed in other Indian populations, there is a significant statistical difference in its distribution among the studied populations. This could be because of the strict endogamy being practiced by the three studied populations. The deviation from Hardy-Weinberg equilibrium observed in case of Muslims could be explained by the observed comparatively higher positive inbreeding coefficient among them.
Though the Muslims of Manipur are believed to have migrated from Sylhet (now in Bangladesh), the