International Mammalian Genome Society

F18 Genetic Mapping of the Bent Tail Mutation and the Identification of a Small X Chromosomal Deletion Associated with the Mutation

Carrel, T. L., Wilbur Harrison* and Frederick Elder*, and Herman, G. E. Children's Research Institute, Department of Pediatrics, and The Molecular, Cellular and Developmental Biology Program, The Ohio State Unviversity, Columbus, Ohio. USA; *Dept of Pathology, University of Texas Health Sciences Center, Houston, TX

In regards to human congenital malformations, the frequency of neural tube defects is second only to congenital heart disease among newborns with an estimated incidence of between 1-9/1000 total births. Several mouse mutants exist that are presumed models of human neural tube defects. Bent tail (Bn) is a spontaneous mutation on the mouse X chromosome that produces tail deformities. Defects are observed in homozygous females and hemizygous males as short, kinked tails. Heterozygous females show variable expression due to X-inactivation. A backcross between inbred Bn and C3H mice was established, and PCR-based polymorphic microsatellites have been utilized to map the Bn locus as a prelude to isolation of the gene. In a panel of 292 normal and affected male and affected female backcross progeny, the locus has been confined to the region between DXMit166 and DXMit140 (cen - DXMit89 - 18.49 ± 2.28 cM - DXMit166 - 1.37 ± 0.68 cM - (DXMit208, Bn ) - 1.03 ± 0.59 cM - DXMit140 - 4.79±1.25 cM -DXBay6.) A high occurrence (at least 6%) of nondisjunction was found in the background strain on which the Bn mutation arose. Recently, we have identified a small submicroscopic deletion containing the microsatellite DXMit208 in Bn affected males. This deletion is believed to harbor the gene(s) responsible for the Bn phenotype. We are presently attempting to determine the extent of the deletion and identify candidate genes within it.