An embryonal carcinoma multiple phenotype locus maps to the proximal position of the mouse X chromosome

A mutant embryonal carcinoma cell line, NR1-6, was established subsequent t o retroviral insertion. The insertion was shown to be causative for a numbe r of aberrant properties associated with the mutant cells. Analysis of >17 kb of the insertion site flanking region failed to reveal any homology betw een this locus and any reported sequence with the exception of one EST of u nknown function and a few repetitive elements including B1 element and a CA dinucleotide repeat. CA repeats occur commonly in the mouse genome and usu ally show size variation. In this study, we mapped this multiphenotype locu s using CA repeat polymorphism and Jackson Laboratory's interspecific backc ross panels. The locus maps to the proximal end of the X chromosome between MGI offsets 1.5 and 4.5 and has been designated DXUalb1. There are several interesting candidate genes within this region. Analyses of their expressi on pattern may lead us to a better understanding of the molecular regulatio n of the variant mutant phenotypes.