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The rare human fragile site 16B.
U Felbor1, W Feichtinger, M Schmid
1Institut für Humangenetik, Biozentrum, Würzburg, Germany.
Cytogenetic and Genome Research
|October 4, 2003
Summary
The human fragile site 16B (FRA16B), a common rare fragile site, is an amplified AT-rich minisatellite repeat. Individuals with FRA16B, even homozygotes, show normal development, indicating no interference with essential gene expression.
Area of Science:
- Human genetics
- Cytogenetics
- Molecular biology
Background:
- The human fragile site 16B (FRA16B) is a rare chromosomal abnormality.
- FRA16B expression can be induced by chemicals targeting AT-rich DNA regions.
Purpose of the Study:
- To determine the frequency and molecular basis of FRA16B.
- To assess the impact of FRA16B on human development.
Main Methods:
- Induction of fragile sites in lymphocyte cultures using berenil.
- Cytogenetic analysis to determine heterozygote frequency.
- Molecular characterization of the FRA16B repeat sequence.
Main Results:
- FRA16B heterozygote frequency is approximately 5% in European populations, making it the most common rare fragile site.
- FRA16B is characterized by amplified 33-base pair AT-rich minisatellite repeats (15-70 kb expansions).
- Heterozygotes and homozygotes for FRA16B are phenotypically normal.
Conclusions:
- FRA16B is a common genetic variation characterized by large AT-rich minisatellite expansions.
- The presence of FRA16B does not adversely affect essential gene expression or human development.