| First Author | Beechey CV | Year | 1993 |
| Journal | Mouse Genome | Volume | 91 |
| Issue | 4 | Pages | 857 |
| Mgi Jnum | J:16261 | Mgi Id | MGI:64345 |
| Citation | Beechey CV (1993) Genetic mapping studies of the distal chromosome 7 imprinting region. Mouse Genome 91(4):857 |
| abstractText | Full text of Mouse Genome contribution: 7. Genetic mapping studies of the distal chromosome 7 imprinting region. There are five known imprinting effects associated with mouse chr 7 as detailed by Cattanach et al. Nature Genetics, 2:270-274, 1992 and Searle and Beechey, Genetic Research 56:237-244, 1990. Recently the two distal effects have been shown to be defined by the translocation breakpoint of T(7;13)7Ad in band 7F3 (Beechey, Mouse Genome 91:310-311, 1993), these being a mid gestational lethality with maternal duplication, and an early embryonic lethality with paternal duplication of this region. Genetic mapping studies have now been completed with T7Ad against the chr 7 genetic markers pink-eyed dilution (p) and chinchilla (cch). + + T7Ad/p cch + males were backcrossed to homozygous p cch females and, after classification, the progeny were tested for T7Ad. The following classes of progeny were obtained: 28 T7Ad; 30 p cch; 1 +; 1 p cch T7Ad; 12 p T7Ad; 4 cch 0 p and 0 cch T7Ad, total 76. Thus the order judging by the rarity of double recombinants is p - cch - T7Ad. The RF between cch and T7Ad was 2.6 +/- 1.8% while that between p and cch was 21.0 +/- 4.7%. The latter value is larger than the RF of 14 cM given by Lyon and Kirby, Mouse Genome 91: 40-80, 1993, suggesting that T7Ad may enhance crossing over in this region. On the other hand, two lines of evidence suggest that crossing over between the c locus and the T7Ad breakpoint may be substantially suppressed. First, there is a lack of collinearity of the genetic and cytological data regarding another translocation in this region of chr 7, T(7;18)50H. Its breakpoint is in 7E2 (Evans, Mouse Genome 89:551, 1991), several bands proximal to T7Ad, yet its genetic breakpoint is distal to T7Ad being between sh-1 and fr, 4 units from the former (Beechey and Searle, Mouse News Letter 46:28, 1972). Second, the imprinted genes, H19 and Igf2 (Zemel et al., Nature Genetics 2: 61-65, 1992), are located 30 units distal to c (Lyon and Kirby ibid) and, if responsible for the distal chr 7 imprinting phenotypes, should locate distal to T7Ad; that they should lie as much as 27 units distal to T7Ad seems unlikely in view of the location of the breakpoint at band F3. (Beechey). |
