A novel polymorphism associated with lactose tolerance in Africa : multiple causes for lactase persistence?
In: Human genetics, Jg. 120 (2007), Heft 6, S. 779-788
Online
academicJournal
- print, 3/4 p
Zugriff:
Persistence or non-persistence of lactase expression into adult life is a polymorphic trait that has been attributed to a single nucleotide polymorphism (C-13910T) in an enhancer element 13.9 kb upstream of the lactase gene (LCT). The -13910*T allele occurs at very high frequency in northern Europeans as part of a very long haplotype (known as A), and promotes binding of the transcription factor Oct-1. However, -13910*T is at very low frequency in many African milk drinking pastoralist groups where lactase persistence phenotype has been reported at high frequency. We report here for the first time, a cohort study of lactose digester and non-digester Sudanese volunteers and show there is no association of -13910*T or the A haplotype with lactase persistence. We support this finding with new genotype/phenotype frequency comparisons in pastoralist groups of eastern African and Middle Eastern origin. Resequencing revealed three new SNPs in close proximity to -13910*T, two of which are within the Oct-1 binding site. The most frequent of these (-13915*G) is associated with lactose tolerance in the cohort study, providing evidence for a cis-acting effect. Despite its location, -13915*G abolishes, rather than enhances Oct-1 binding, indicating that this particular interaction is unlikely to be involved in lactase persistence. This study reveals the complexity of this phenotypic polymorphism and highlights the limitations of C-13910T as a diagnostic test for lactase persistence status, at least for people with non-European ancestry.
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A novel polymorphism associated with lactose tolerance in Africa : multiple causes for lactase persistence?
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Autor/in / Beteiligte Person: | INGRAM, Catherine J. E ; ELAMIN, Mohamed F ; SWALLOW, Dallas M ; MULCARE, Charlotte A ; WEALE, Michael E ; TAREKEGN, Ayele ; OLJIRA RAGA, Tamiru ; BEKELE, Endashaw ; ELAMIN, Farouk M ; THOMAS, Mark G ; BRADMAN, Neil |
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Zeitschrift: | Human genetics, Jg. 120 (2007), Heft 6, S. 779-788 |
Veröffentlichung: | Berlin; Heidelberg; New York, NY: Springer, 2007 |
Medientyp: | academicJournal |
Umfang: | print, 3/4 p |
ISSN: | 0340-6717 (print) |
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