Screening of variants for lactase persistence/non-persistence in populations from South Africa and Ghana

Abstract

Lactase non-persistence is a condition where lactase activity is decreased in the intestinal wall after weaning. In European derived populations a single nucleotide polymorphism (SNP) C/T_-13910 residing 13.9 kb upstream from the lactase gene has been shown to define lactase activity, and several other single nucleotide polymorphisms (G/C_-14010 T/G_-13915, C/G_-13907 and T/C_-13913) in the same region have been identified in African and Middle East populations. The T_-13910 allele most common in European populations was present in 21.8% mixed ancestry (N = 62) individuals and it was absent in the Xhosa (N = 109) and Ghana (N = 196) subjects. Five other substitutions were also found in the region covering the previously reported variants in African and Middle East populations. These included the G/C_-14010 variant common in Kenyan and Tanzanian populations, which was present in 12.8% of Xhosa population and in 8.1% of mixed ancestry subjects. Two novel substitutions (C/T_-14091 and A/C_-14176) and one previously reported substitution G/A_-13937 (rs4988234) were less common and present only in the Xhosa population. One novel substitution G/A_-14107 was present in the Xhosa and Ghanaian populations. None of the other previously reported variants were identified. Identification of the G/C_-14010 variant in the Xhosa population, further confirms their genetic relatedness to other nomadic populations members that belong to the Bantu linguistic group in Tanzania and Kenya. Further studies are needed to confirm the possible relationship of the novel substitutions to the lactase persistence trait.