Abstract
Lactase persistence (LP) is a well-studied example of a Mendelian trait under selection in some human groups due to gene-culture coevolution.We investigated the frequencies of genetic variants linked to LP in Sudanese and South Sudanese populations. These populations have diverse subsistence patterns, and someare dependent on milk to various extents, not only fromcows but also from other livestock such as camels and goats.We sequenced a 316-bp region involved in regulating the expression of the LCT gene on chromosome 2,which encompasses five polymorphisms that have been associatedwith LP. Pastoralist populations showed a higher frequency of LP-associated alleles compared with nonpastoralist groups, hinting at positive selection also among northeast African pastoralists. Among the LP variants, the -14009:G variant occurs at the highest frequency among the investigated populations, followed by the -13915:Gvariant,which is likely ofMiddle Eastern origin, consistentwithMiddle Eastern gene flowto the Sudanese populations. Therewasno incidence of the“EastAfrican” LP allele (-14010:C) in the Sudanese andSouthSudanesegroups, andonly one heterozygous individual for the “European” LP allele (-13910:T), suggesting limited recent admixture from these geographic regions. The Beja population of the BeniAmer show three different LP variants at substantial and similar levels, resulting in one of the greatest aggregation of LP variants among all populations across the world.