Lactase persistence in Tunisia as a result of admixture with other Mediterranean populations

Yosra Ben Halima, Rym Kefi, Marco Sazzini, Cristina Giuliani, Sara De Fanti, Chokri Nouali, Majdi Nagara, Giacomo Mengozzi, Sahar Elouej, Abdelmajid Abid, Henda Jamoussi, Lotfi Chouchane, Giovanni Romeo, Sonia Abdelhak, Donata Luiselli

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3 Citations (Scopus)

Abstract

Background: The ability to digest lactose after weaning, namely, lactase persistence (LP), is encoded by polymorphisms in the MCM6 gene and varies widely in frequency among different human populations. Although, evolution of LP-related genetic variants was investigated in many groups of Sub-Saharan African, Middle Eastern, and European ancestry, only few studies have focused on populations from North Africa and no data are especially available from the Tunisian one. For this reason, there is an urgent need to investigate the frequency patterns at these loci in Tunisia since this adaptive trait is implicated in health. Methods: Forty SNPs covering the LCT/MCM6 genes and including the two functional variants − 13,910 C > T and − 22,018 G > A were genotyped in 117 Tunisian individuals using the Sequenom Mass Array technology. The observed nucleotide and haplotype patterns of variation were then compared with those of several African, European, and Mediterranean human groups for which comparable data were publicly available. Admixture analysis on a 5 Mb genomic region surrounding the LCT/MCM6 loci was also performed by extracting genotypes from a previously generated genome-wide dataset in order to deepen the reconstruction of the evolutionary history of these loci. Results: We found that lactase non-persistence (LNP)-related alleles and haplotypes were predominantly present in the examined population. A clear differentiation between Tunisian, African, and North European/North Italian samples was found, while the Tunisian population showed more genetic affinity to Central and South Italian groups. Conclusions: Our study provided a first report of LP-associated alleles and haplotypes in the Tunisian population. We highlighted a gradient followed by LP diffusion from Europe to North Africa. Based on the rich historic background of Tunisia, we suggest that this adaptive trait was introduced in that geographic region by a relatively recent gene flow.

Original languageEnglish
Article number20
JournalGenes and Nutrition
Volume12
Issue number1
DOIs
Publication statusPublished - 24 Aug 2017

Keywords

  • Admixture
  • LCT
  • Lactase persistence
  • MCM6
  • Natural selection
  • North Africa
  • Tunisia

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Genetics

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    Ben Halima, Y., Kefi, R., Sazzini, M., Giuliani, C., De Fanti, S., Nouali, C., Nagara, M., Mengozzi, G., Elouej, S., Abid, A., Jamoussi, H., Chouchane, L., Romeo, G., Abdelhak, S., & Luiselli, D. (2017). Lactase persistence in Tunisia as a result of admixture with other Mediterranean populations. Genes and Nutrition, 12(1), [20]. https://doi.org/10.1186/s12263-017-0573-3