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Updated: Jul 27, 2026

FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
T(In1;5)44H, a complex mouse chromosomal rearrangement with a phenotypic effect
E P Evans1, C V Beechey, M D Burtenshaw
1MRC Radiobiology Unit, Didcot, Oxon, UK.
A complex chromosomal rearrangement in mice, T(In1;5)44H, was identified after X-irradiation. This genetic abnormality leads to reduced litter sizes and embryonic mortality in carriers.
Area of Science:
- Genetics
- Cytogenetics
- Radiation Biology
Background:
- Spermatogonial X-irradiation can induce complex chromosomal rearrangements.
- Understanding these rearrangements is crucial for assessing radiation-induced genetic damage.
Purpose of the Study:
- To characterize a complex murine chromosomal rearrangement, T(In1;5)44H, induced by fractionated X-irradiation.
- To investigate the meiotic behavior and reproductive consequences of this rearrangement.
Main Methods:
- Recovery and characterization of the T(In1;5)44H chromosomal rearrangement in mice.
- Linkage analysis to determine gene order on chromosomes 1 and 5.
- Meiotic analysis in heterozygotes to study chromosome pairing and segregation.
- Assessment of fertility and litter characteristics in carriers.
Main Results:
- T(In1;5)44H involves a paracentric inversion of Chromosome 1 and a reciprocal translocation with Chromosome 5.
- Linkage tests established gene order on Chr 1 (fz-ln-T44H) and Chr 5 (W-T44H-go-bf).
- Heterozygotes exhibit coat color dilution, reduced fertility, small litter sizes, and a shortage of carrier offspring.
- Meiotic analysis revealed regular pairing and chiasma formation, producing dicentric chromatids that likely cause embryonic mortality.
Conclusions:
- The T(In1;5)44H rearrangement, despite its complexity, undergoes regular meiosis.
- The observed reproductive inefficiencies are attributed to the formation and segregation of dicentric chromatids during meiosis.
- This study provides insights into the genetic and reproductive consequences of complex chromosomal rearrangements induced by radiation.
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