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Localization of am3 using EL congenic mouse strains
1Department of Pediatric Dentistry, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Chiba 271-8587, Japan. takehiko@mascat.nihon-u.ac.jp
Journal of Dental Research
|March 26, 2005
Summary
The absence of third molars (M3) in EL/Sea mice is linked to a specific genetic locus (am3) on chromosome 3. Congenic mouse strains confirmed this locus and suggest additional genes also influence M3 development.
Area of Science:
- Genetics
- Developmental Biology
- Mammalian Genetics
Background:
- EL/Sea mice exhibit a 100% incidence of the absence of third molars (M3).
- Previous linkage analysis identified a major locus, am3, on chromosome 3 associated with M3 absence in EL/Sea mice.
Purpose of the Study:
- To obtain independent evidence for the linkage of the am3 locus.
- To more precisely determine the chromosomal location of the am3 locus.
- To investigate the genetic basis of third molar agenesis in EL/Sea mice.
Main Methods:
- Generation of EL/Sea congenic mouse strains by replacing a specific chromosome 3 interval with the MSM/Msf homologue.
- Analysis of third molar incidence in EL/Sea congenic mice heterozygous or homozygous for the introduced interval.
- Confirmation of linkage and refinement of the am3 locus location.
Main Results:
- EL/Sea congenic mice showed a significant decrease in the incidence of M3 absence.
- The am3 locus was confined to an approximately 4.4-cM region on chromosome 3.
- Evidence suggests that unmapped genes also contribute to M3 agenesis in EL/Sea mice.
Conclusions:
- The am3 locus on chromosome 3 is confirmed as a major genetic factor influencing third molar development.
- Congenic strain analysis refines the location of the am3 locus.
- The absence of third molars in EL/Sea mice is a complex trait involving multiple genetic factors.