State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China.
Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, China.
Hum Genomics. 2019 Feb 11;13(1):7. doi: 10.1186/s40246-019-0195-5.
The ability to digest dietary lactose is associated with lactase persistence (LP) in the intestinal lumen in human. The genetic basis of LP has been investigated in many populations in the world. Iran has a long history of pastoralism and the daily consumption of dairy products; thus, we aim to assess how LP has evolved in the Iranian population. We recruited 400 adult individuals from seven Iranian ethnic groups, from whom we investigated their lactose tolerance and screened the genetic variants in their lactase gene locus.
The LP frequency distribution ranged from 0 to 29.9% in the seven Iranian ethnic groups with an average value of 9.8%. The variants, - 13910T and - 22018A, were significantly associated with LP phenotype in Iranians. We found no evidence of hard selective sweep for - 13910T and - 22018A in Persians, the largest ethnic group of Iran. The extremely low frequency of - 13915*G in the Iranian population challenged the view that LP distribution in Iran resulted from the demic diffusion, especially mediated by the spread of Islam, from the Arabian Peninsula.
Our results indicate the distribution of LP in seven ethnic groups across the Iranian plateau. Soft selective sweep rather than hard selective sweep played a substantial role in the evolution of LP in Iranian populations.
在人类的肠道腔中，消化膳食乳糖的能力与乳糖酶持续存在（LP）相关。LP 的遗传基础已在世界上许多人群中进行了研究。伊朗有着悠久的游牧历史和乳制品的日常消费；因此，我们旨在评估 LP 在伊朗人群中是如何进化的。我们从七个伊朗民族群体中招募了 400 名成年个体，从他们那里调查了乳糖耐受性，并筛选了他们乳糖酶基因座中的遗传变异。
在七个伊朗民族群体中，LP 频率分布范围从 0 到 29.9%，平均值为 9.8%。-13910T 和-22018A 变体与伊朗人的 LP 表型显著相关。我们没有发现-13910T 和-22018A 在波斯人中（伊朗最大的民族群体）经历硬选择清除的证据。伊朗人口中-13915*G 的极低频率挑战了 LP 分布在伊朗是由阿拉伯半岛的伊斯兰教传播介导的人群扩散导致的观点。
我们的结果表明 LP 在伊朗高原七个民族群体中的分布。软选择清除而不是硬选择清除在伊朗人群中 LP 的进化中发挥了重要作用。
