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The lactase persistence/non-persistence polymorphism is controlled by a cis-acting element
Y Wang1, C B Harvey, W S Pratt
1MRC Human Biochemical Genetics Unit, Galton Laboratory (UCL), London, UK.
Human Molecular Genetics
|April 1, 1995
Summary
Lactase persistence, the ability to digest milk sugar in adulthood, is genetically controlled. This study suggests the genetic variation responsible for lactase persistence is located near the lactase gene itself.
Area of Science:
- Genetics
- Human Physiology
- Molecular Biology
Background:
- Lactase activity in the small intestine varies among adult humans due to a genetic polymorphism affecting lactase gene expression.
- The molecular basis for this lactase persistence polymorphism remains elusive, with uncertainty regarding whether regulatory differences are within or outside the lactase gene.
Purpose of the Study:
- To investigate whether the genetic regulation of lactase persistence operates in cis or trans.
- To pinpoint the genomic location of the nucleotide substitutions responsible for lactase persistence/non-persistence.
Main Methods:
- Exploitation of known DNA marker polymorphisms within lactase gene exons.
- Examination of individual lactase mRNA transcript expression in lactase persistent and non-persistent individuals.
Main Results:
- In some lactase persistent individuals, one lactase gene allele exhibited significantly lower expression than the other.
- These individuals often displayed intermediate lactase activity levels.
Conclusions:
- The observed allele-specific expression patterns suggest that the genetic basis for lactase persistence is cis-acting.
- This finding significantly narrows the search area within the genome for the causative nucleotide differences.