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Identification of a cryptic lethal mutation in the mouse t(w73) haplotype
Gareth R Howell1, Rebecca A Bergstrom, Robert J Munroe
1The Jackson Laboratory, Bar Harbor, Maine 04609, USA.
Genetical Research
|April 13, 2005
Summary
T haplotypes, variant forms on mouse chromosome 17, harbor mutations causing male sterility and lethality. Researchers discovered a new, hidden lethal mutation in the t(w73) haplotype, suggesting these regions accumulate multiple mutations.
Area of Science:
- Genetics
- Developmental Biology
- Evolutionary Biology
Background:
- T haplotypes are naturally occurring variants of the mouse T-complex on chromosome 17, defined by four inversions.
- These haplotypes carry mutations leading to male sterility, transmission ratio distortion (TRD), and embryonic lethality.
- Previous studies identified at least 16 complementation groups for lethal mutations, primarily focusing on embryonic lethality due to homozygosity for single genes.
Purpose of the Study:
- To investigate the potential for multiple mutations within t haplotypes.
- To screen the t(w73) haplotype for novel mutations that may be obscured by existing lethal alleles.
Main Methods:
- Utilized deletion complexes covering the proximal two-thirds of the T-complex to overcome recombination suppression.
- Screened the t(w73) haplotype for new lethal alleles by analyzing mice carrying both the haplotype and selected deletions.
Main Results:
- Identified a novel mutation located between markers D17Jcs41 and D17Mit100.
- Mice heterozygous for t(w73) and specific deletions exhibited lethality at birth, prior to feeding, indicating a cryptic lethal allele.
Conclusions:
- The discovery of a new, cryptic lethal mutation in t haplotypes suggests these regions can accumulate multiple recessive mutations.
- Recombinationally suppressed regions like t haplotypes may act as reservoirs for the accumulation of genetic variations affecting development.