Genetic Heterogeneity and Ethno-historical Considerations of Burusho and Balti Tribes with Regard to ABO and Rh Blood Group Alleles

Abstract

regard to ABO and Rh group alleles of Burusho and
Balti tribes of northern Pakistan in order to determine
origin of these populations.
Methods: A prospective study was conducted from
November 2006 to January 2007 at Combined Military
Hospital Gilgit in which a total of 4318 blood samples
were taken for ABO and Rh D blood grouping. They
comprised of 3210 samples taken from the Burusho and
1008 samples of the Balti population. The method of
sampling was random. Genetic affinities and gene
diversity of the two populations was determined in terms
of genetic distancing analysis with regards to ABO and
Rh loci.
Results: The average ABO allele frequencies in the
Burusho population were ABO*A (0.37) ABO*B (0.32)
ABO*AB (0.02) and ABO*O (0.29). Similarly the average
allele frequencies of Balti population were ABO*A (0.23)
ABO*B (0.31) ABO*AB (0.09) and ABO*O (0.37). In Brusho
alleles frequencies for D and d of the Rh group
system were 0.942 and 0.0580, for Balti 0.950 and 0.500
respectively for the total data. There is a marked increase
in the frequency of blood group gene A in Burusho
population and a corresponding decrease in blood
group gene O as we proceed from older to younger age
groups. Also there is significant divergence (p <0.05) in
Burusho population for the distribution of ABO alleles
from the general South Asiatic trend (O greater than B
greater than A). Probably because of the relatively small
starting value of r < 0.5 a selection took place against group
O resulting in an increase of the blood group gene A in
Burusho population.
Conclusion: The genetic distance analysis reveals
that the two tribes included in this study are genetically
distant from one another and the genetic clustering
pattern correlates with linguistic/ethnic affiliation and
geographical proximity of these tribal populations to a
certain extent.