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Background: Cytokines are cell signaling molecules which upon release by cells facilitate the recruitment of immune-modulatory cells towards the sites of inflammation. Genetic variations in cytokine genes are shown to regulate their production and affect the risk of infectious as well as autoimmune diseases. Intron-3 of interleukin-4 gene (IL-4) harbors 70-bp variable number of tandem repeats (VNTR) that may alter the expression level of IL-4 gene., Objective: To determine the distribution of IL-4 70-bp VNTR polymorphism in seven genetically heterogeneous populations of Chhattisgarh, India and their comparison with the finding of other Indian and world populations., Methods: A total of 371 healthy unrelated individuals from 5 caste and 2 tribal populations were included in the present study. The IL-4 70-bp VNTR genotyping was carried out using PCR and electrophoresis., Results: Overall, 3 alleles of IL-4 70-bp VNTR (a2, a3 and a4) were detected. The results demonstrated the variability of the IL-4 70-bp VNTR polymorphism in Chhattisgarh populations. Allele a3 was the most common allele at the 70-bp VNTR locus in all populations followed by a2 allele. This study reports the presence four repeat allele a4 at a low frequency in the majority of the Chhattisgarh populations studied. Further, the frequency of the minor allele (a2) in Chhattisgarh populations showed similarity with the frequencies of European populations but not with the East Asian populations where the a2 allele is a major allele., Conclusions: Our study provides a baseline for future research into the role of the IL-4 locus in diseases linked to inflammation in Indian populations.

The dopamine transporter (DAT1) is a membrane spanning protein that binds the neurotransmitter dopamine and performs re-uptake of dopamine from the synapse into a neuron. The gene encoding DAT1 consists of 15 exons spanning 60 kb on chromosome 5p15.32. Several studies have investigated the possible associations between variants in DAT1 gene and psychiatric disorders. The present study aimed to determine the distribution of the variable number of tandem repeat (VNTR) polymorphism in the 3' untranslated region of DAT1 in 12 Indian populations. A total of 471 healthy unrelated individuals in 12 Indian populations from 3 linguistic groups were included in the present study. The analysis was carried out using PCR and electrophoresis. Overall, 4 alleles of the DAT1 40-bp VNTR, ranging from 7 to 11 repeats were detected. Heterozygosity indices were low and varied from 0.114 to 0.406. The results demonstrate the variability of the DAT1 40-bp VNTR polymorphism in Indian populations and revealed a high similarity with East Asian populations.

The human dopaminergic system is a significant focal point of study in the fields of neuropsychiatry and pharmacology, plus it is also a promising nuclear DNA marker in studies of human genome diversity. In this study, we assayed six polymorphic markers in the dopamine D2 receptor gene (DRD2) in 482 unrelated individuals from nine ethnic populations of India. Our results demonstrate that the six markers are highly polymorphic in all populations and the constructed haplotypes show a high level of heterozygosity. Out of the eight possible three-site haplotypes, all populations commonly shared only three haplotypes. The haplotypes exhibited fairly high frequencies across multiple populations; Kurumba population showed all eight three-site haplotypes. The ancestral haplotype (B2-D2-Al) was observed at high frequency only in the Siddi population. Haplotypes based on all six markers revealed 16 haplotypes, out of which only 6 are most common with a frequency of greater than 5% in at least one of the nine populations. But only three haplotypes were shared by all nine populations with the cumulative frequency ranging from 80.8% (Kurumba) to 96.6% (Onge). Great variation in levels of linkage disequilibrium (LD) was detected, ranging from complete LD in the Badaga to virtually no LD in the Siddi. This range of LD likely reflects different population histories, such as African ancestry in the Siddi and recent founding events in the population isolates, Badaga and Kota.