Fmn1^ld-TgBri137

A 3.6 kb transgene replaced a large genomic segment (at least 36 kb) including exons 20-22, and disrupted a regulatory element that affects the expression of the downstream Grem1 gene. The deletion overlaps an 11 kb interval involved in two other limb deformity alleles: the Fmn1ld-TgHD insertion/deletion and the Fmn1ld-Is(17;In2)1Gso chromosomal rearrangement. This mutation was determined by complementation analyses to be allelic to Fmn1ld-TgHD, Grem1ld, and Grem1ld-J. The transgene contains 1.1 kb of 5' flanking sequence from the rat myelin protein zero gene (Mpz) fused to a mutant simian virus 40 early region sequence (tsA-1609). Ribonuclease protection assays suggest that isoform IV transcripts produced by the 3' region of this allele are disrupted. No differences were detected between mutant and wild-type transcripts produced by the 5' and central regions of the gene. (J:1741, J:38417)