The murine homolog of the human breast and ovarian cancer susceptibility gene Brca1 maps to mouse chromosome 11D

The recently cloned human breast and ovarian cancer suseptibility gene, BRCA1, is located on human chromosome 17q21. We have isolated murine genomic clones containing Brca1 as a first step in generating a mouse model for the loss of BRCA1 function. A mouse genomic library was screened using probes corresponding to exon 11 of the human BRCA1 gene. Two overlapping mouse clones were identified that hybridized to human BRCA1 exons 9-12. Sequence analysis of 1.4 kb of the region of these clones corresponding to part of human exon 11 revealed 72% nucleic acid identity but only 50% amino acid identity with the human gene. The longest of the mouse Brcal genomic clones maps to chromosome 11D, as determined by two-color fluorescence in situ hybridization. The synteny to human chromosome 17 was confirmed by cohybridization with the mouse probe for the NF1-gene. This comparative study confirms that the relative location of the BRCA1 gene has been conserved between mice and humans.