Lactase persistence is a genetic trait that determines the ability to express high levels of lactase enzyme as adults. In order to have an impression on the frequency of lactase persistence phenotype and underlying genotypes among Sudanese, a total of 298 DNA samples were collected. Lactose tolerance test was performed. PCR-RFLP and ARMS-PCR were used. Our results showed variations in frequencies of the lactase persistence phenotype among Sudanese populations, with significant association with their lifestyle (P = 0.01). The -13910*T allele that is associated with lactase persistence in Finnish was absent in all populations and was only found in 0.07 of the Fulani group. Based on Tajimas test for selective neutrality the results suggest the presence of balancing selection. Some of the combined haplotypes are common to all groups while others were specific to particular lifestyles. We observe a signal of a haplotype (CAC). The absence of -13910*T allele suggest that it is not necessarily associated always with LCTP in different populations and that there might be another underlying polymorphism(s) to account for the LCTP, consistent with Tishkoff and colleagues findings and that this trait might be associated with haplotype (CAC) in Sudanese pastoralists. The presence of -13910*T allele with a frequency of 0.07 in the Fulani may be due to the introgression from migrant populations and/ or a recent incidence of back migration from out of Africa. The departure of the selected SNPs from Hardy-Weinberg Equilibrium indicates the role of selection as an evolutionary force in this region.

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