The high prevalence of lactase persistence (LP) among the people of Saudi Arabia is associated with the-13915*G variant allele upstream of the lactase gene (LCT). We, therefore, examined the frequency of the commonly known LP associated SNPs among randomly collected samples from Omani and Yemeni adult populations and obtained further data on the distribution of the two most common LP-associated variants,-13910*T and-13915T*G, in the Arabian Peninsula. The DNA fragment containing all the reported LP-associated SNPs was amplified and genotyped. The frequency of the-13915*G allele was highest among Dhofari Arabs of southern Oman (0.72) followed by Yemeni Arabs (0.54) and Arabs of northern Oman (0.14). It was not detected in Omanis of Asian origin. The frequency of the-13910*T allele was extremely low in Arabs of northern and southern Oman (0.00 0.01) and Yemenis (0.002). However, it had a frequency of 0.160 among Omanis of Asian origin. Results show that the highest frequency of the LCT-13915*G variant allele appears to be in the south of the Arabian Peninsula with clinal decrease within the Peninsula and further out in surrounding countries.
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