The evolutionary genetics of lactase persistence in seven ethnic groups across the Iranian plateau

Charati, Hadi; Peng, Min‐Sheng; Chen, Wei; Yang, Xing-Yan; Ori, Roghayeh Jabbari; Aghajanpour-Mir, Mohsen; Esmailizadeh, Ali; Zhang, Yaping

doi:10.1186/s40246-019-0195-5

Cited by 12 publications

(11 citation statements)

References 68 publications

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“…So far, only one phenotypic study has been performed (on 30 individuals), showing a LP prevalence of 30% [53], and the genetic basis for LP in these populations is unclear [54]. In parallel, it has recently been shown that there was no significant difference in LP phenotypic frequency between farmers and herders from Iran [55], so ethnographic work could also be done in these populations to see whether their consumption practices match our hypothesis.…”

Section: Discussionmentioning

confidence: 88%

“…For the 3 ancient maps, light/ dark blue points represent individuals for which one randomly chosen read carries the C/T allele. For the modern map, purple points correspond to genetic data from our laboratory [11,16,57]; green points represent genetic data based on [61,62] (including only populations for which −13.910:C>T is the only known mutation associated with LP, i.e., all of Eurasia excluding the Arabian Peninsula), and blue points represent inferences of the T allele frequency from direct phenotypic measurements (from the GLAD database [63], as well as from [55], merging what the authors define as LP and lactase-intermediate individuals). These maps were obtained by modifying an R script originally written and shared by I. Mathieson.…”

Section: Temporal Dynamic Of Lp In Eurasiamentioning

confidence: 99%

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Why and when was lactase persistence selected for? Insights from Central Asian herders and ancient DNA

et al. 2020

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The genetic adaptation of humans to the consumption of milk from dairying animals is one of the most emblematic cases of recent human evolution. While the phenotypic change under selection, lactase persistence (LP), is known, the evolutionary advantage conferred to persistent individuals remains obscure. One informative but underappreciated observation is that not all populations whose ancestors had access to milk genetically adapted to become lactase persistent. Indeed, Central Asian herders are mostly lactase nonpersistent, despite their significant dietary reliance on dairy products. Investigating the temporal dynamic of the −13.910:C>T Eurasian mutation associated with LP, we found that, after its emergence in Ukraine 5,960 before present (BP), the T allele spread between 4,000 BP and 3,500 BP throughout Eurasia, from Spain to Kazakhstan. The timing and geographical progression of the mutation coincides well with the migration of steppe populations across and outside of Europe. After 3,000 BP, the mutation strongly increased in frequency in Europe, but not in Asia. We propose that Central Asian herders have adapted to milk consumption culturally, by fermentation, and/or by colonic adaptation, rather than genetically. Given the possibility of a nongenetic adaptation to avoid intestinal symptoms when consuming dairy products, the puzzle then becomes this: why has LP been selected for at all? Lactase persistence, a clear-cut case of human adaptation? One of the genetically best known examples of genetic adaptation in humans is the appearance of lactase persistence (LP) in some populations, a phenotype characterized by the maintenance of the lactase gene expression throughout adulthood. This allows individuals to digest the lactose found in milk not just during their childhood but throughout their lives. LP has reached high frequencies in various European, African, and Arab populations whose ancestors have domesticated animals and used their milk since the Neolithic revolution, about 5,000 to 10,000

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Section: Discussionmentioning

confidence: 88%

Section: Temporal Dynamic Of Lp In Eurasiamentioning

confidence: 99%

Why and when was lactase persistence selected for? Insights from Central Asian herders and ancient DNA

et al. 2020

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“…Populations of Native American ancestry, who were excluded from dietary analysis in this study due to low numbers (“Other” ethnicity), had high proportions of the LNP genotype (GG, 68.2%) and low dairy consumption in another study [50]. Participants of Middle Eastern descent were also included in “Other” ethnicity group; a study of seven Iranian populations found LP in 0 to 29.9% of the groups with significant associations between rs4988235, which is another LP-related SNP (ID: rs182549), and the LP phenotype [51]. Due to the small number of individuals in some of the ethnic groups, the current study was likely underpowered for comparisons with individual ethnic groups.…”

Section: Discussionmentioning

confidence: 99%

Association of Lactase Persistence Genotypes (rs4988235) and Ethnicity with Dairy Intake in a Healthy U.S. Population

et al. 2019

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Lactase persistence (LP) is a trait in which lactose can be digested throughout adulthood, while lactase non-persistence (LNP) can cause lactose intolerance and influence dairy consumption. One single nucleotide polymorphism (SNP ID: rs4988235) is often used as a predictor for dairy intake, since it is responsible for LP in people in European descent, and can occur in other ethnic groups. The objective of this study was to determine whether rs4988235 genotypes and ethnicity influence reported dairy consumption in the United States (U.S.). A food frequency questionnaire (FFQ) and multiple Automated Self-Administered 24-h recalls (ASA24®) were used to measure habitual and recent intake, respectively, of total dairy, cheese, cow’s milk, plant-based alternative milk, and yogurt in a multi-ethnic U.S. cohort genotyped for rs4988235. Within Caucasian subjects, LP individuals reported consuming more recent total dairy and habitual total cow’s milk intake. For subjects of all ethnicities, LP individuals consumed more cheese (FFQ p = 0.043, ASA24 p = 0.012) and recent total dairy (ASA24 p = 0.005). For both dietary assessments, Caucasians consumed more cheese than all non-Caucasians (FFQ p = 0.036, ASA24 p = 0.002) independent of genotype, as well as more recent intake of yogurt (ASA24 p = 0.042). LP subjects consumed more total cow’s milk than LNP, but only when accounting for whether subjects were Caucasian or not (FFQ p = 0.015). Fluid milk and alternative plant-based milk consumption were not associated with genotypes or ethnicity. Our results show that both LP genotype and ethnicity influence the intake of some dairy products in a multi-ethnic U.S. cohort, but the ability of rs4988235 genotypes to predict intake may depend on ethnic background, the specific dairy product, and whether intake is reported on a habitual or recent basis. Therefore, ethnicity and the dietary assessment method should also be considered when determining the suitability of rs4988235 as a proxy for dairy intake.

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“…It is hypothesized that natural selection has elicited a prime role in determining the current frequencies of LP in different human communities since the development of cattle domestication in the Middle East and North Africa around ~7500–9000 years before present (BP). Although LP and LNP frequencies have been widely studied worldwide, there is a lack of a work collecting all newly available information published to date [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]; especially the new frequency data reported for American populations. Given the great interest of this research topic, an online graphic resource gathering all reported lactase frequency data (both at the phenotypic and genetics levels) would be of much utility for the scientific community.…”

Section: Introductionmentioning

confidence: 99%

Genetics of Lactose Intolerance: An Updated Review and Online Interactive World Maps of Phenotype and Genotype Frequencies

2020

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In humans the ability to digest milk lactose is conferred by a β-galactosidase enzyme called lactase-phlorizin hydrolase (LPH). While in some humans (approximately two-thirds of humankind) the levels of this enzyme decline drastically after the weaning phase (a trait known as lactase non-persistence (LNP)), some other individuals are capable of maintaining high levels of LPH lifelong (lactase persistence (LP)), thus being able to digest milk during adulthood. Both lactase phenotypes in humans present a complex genetic basis and have been widely investigated during the last decades. The distribution of lactase phenotypes and their associated single nucleotide polymorphisms (SNPs) across human populations has also been extensively studied, though not recently reviewed. All available information has always been presented in the form of static world maps or large dimension tables, so that it would benefit from the newly available visualization tools, such as interactive world maps. Taking all this into consideration, the aims of the present review were: (1) to gather and summarize all available information on LNP and LP genetic mechanisms and evolutionary adaptation theories, and (2) to create online interactive world maps, including all LP phenotype and genotype frequency data reported to date. As a result, we have created two online interactive resources, which constitute an upgrade over previously published static world maps, and allow users a personalized data exploration, while at the same time accessing complete reports by population or ethnicity.

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The evolutionary genetics of lactase persistence in seven ethnic groups across the Iranian plateau

Cited by 12 publications

References 68 publications

Why and when was lactase persistence selected for? Insights from Central Asian herders and ancient DNA

Why and when was lactase persistence selected for? Insights from Central Asian herders and ancient DNA

Association of Lactase Persistence Genotypes (rs4988235) and Ethnicity with Dairy Intake in a Healthy U.S. Population

Genetics of Lactose Intolerance: An Updated Review and Online Interactive World Maps of Phenotype and Genotype Frequencies

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