THE MOUSE CHROMOSOME-7 DISTAL IMPRINTING DOMAIN MAPS TO G-BANDS F4 F5/

Mouse Chromosome (Chr) 7 distal to band F3 on the physical map is know n to be subject to imprinting, maternal duplication (MatDp) of the reg ion leading to a late embryonic lethality, while paternal duplication (PatDp) causes death in utero before 11.5 dpc. Using a new mouse recip rocal translocation T(7;11)65H to produce MatDp for distal Chr 7, we h ave mapped the region subject to imprinting more precisely to bands 7F 4/F5 on the cytogenetic map. Fluorescence in situ hybridization (FISH) studies on mitotic and meiotic chromosomes of a T65H heterozygote sho w that the imprinted gene Igf2 is located in the same region. This was confirmed by the finding that embryos with MatDp of bands 7F4/F5 did not express Igf2. We suggest that other members of the imprinted domai n containing Igf2, namely Mash2, H19, Ins2, and p57(K1P2), also locate d in 7F4/F5 and that some or all of these genes may be responsible for the two imprinting lethalities seen with MatDp and PatDp for this reg ion.