International Mammalian Genome Society


The 13th International Mouse Genome Conference
October 31-November 3, 1999

Table of Contents * Structure * Bioinformatics * Sequence * Mapping * New Tools * Gene Discovery * Developmental * Mutagenesis * Functional Genomics

F14 crsp - A New Mouse Trasgene Insertional Mutation Causing Cryptorchidism

C. E. Bishop1, 2, P. A. Overbeek3, J. B. Houston4, R. Sutherland4, H. L. Boettger-Tong1, A. I. Agulnik1. 1Baylor College of Medicine, Depts. Ob/Gyn1, Molecular and Human Genetics2, Cell Biology3, Urology4, Houston, TX, 77030, USA

In human populations cryptorchidism occurs in 3-4% of males at birth, making this abnormality the most frequent congenital birth defect in newborn boys. Identification of the genes that play a role in the etiology and pathogenesis of cryptorchidism is a key to the better understanding of this abnormality. A new mouse transgene insertional mutation (crsp - cryptorchidism with white spotting) has been identified at the Baylor College of Medicine. Males homozygous for crsp exhibit high intraabdominal cryptorchidism, associated with complete sterility. Only a few spermatogonial cells are present in the small undescended testis in adult males. Histological examination of the surgical descended testes in crsp/crsp males after 2 monthes since the operation revealed normal spermatogenesis and the presence of the sperm in the epididymis indicating that crsp is not essential for male germ cell development, but rather for the testis descent during development. No heterozygous effect is detectable and homozygous females are fully fertile. FISH analysis with a transgene probe localized the insertion site to the distal region of mouse chromosome 5. We have cloned an insertional breakpoint of crsp and mapped the mutation to a genetic interval of less than 1cM using interspecific backcross analysis. It was established that the transgene insertion caused a deletion of a genomic DNA. The YAC and BAC contigs of the critical region have been constructed. The crsp mutation is located in the immediate proximity of the mouse Brca2 locus. The homologous region in human chromosome 13q12-13 has been extremely well-characterized previously. Using available human genomic sequence information and a series of mouse STSs/ESTs, we constructed a gene map of the homologous mouse region. A candidate gene for crsp that lacks the first 5'exon in the mutants has been identified.

 


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