Danciger J S, Danciger M, Nusinowitz S, Rickabaugh T, Farber D B
Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095-7008, USA.
Mamm Genome. 1999 Jul;10(7):657-61. doi: 10.1007/s003359901067.
The rd3 retinal degeneration gene was previously mapped 10 +/- 2.5 cM distal to Akp1 on mouse Chromosome (Chr) 1 (Chang et al., 1993), a region that may be homologous to the locus of the human USH2A gene, which carries mutations responsible for Usher IIa retinal degeneration/hearing loss syndrome. An intercross from an Rb(11, 13)4Bnr(rd3/rd3) x C57BL/6J mating was set up, 428 F2 meioses were analyzed, and the rd3 gene was placed between the markers D1MIT292/D1MIT209 and D1MIT510, a distance of 1.40 +/- 0.57 cM. These flanking markers and the mouse ortholog of USH2A (Mush2a) were mapped in the T31 mouse radiation hybrid (RH) panel, with the result that D1MIT292/D1MIT209 and D1MIT510 were 7.9 cR3000 apart ( approximately 800 kb), and Mush2a was > 30 cR3000 proximal to the pair, excluding it from the rd3 locus. A contig spanning the rd3 locus and consisting of 2 YACs and one BAC was generated, and Mush2a was absent from it, confirming its exclusion from the locus. Comparison of adjacent marker pairs in the Whitehead genetic map and our genetic map showed some discrepancies in order of markers and genetic distances. Comparison of our genetic map and the RH map showed some highly skewed relationships between genetic and physical distances.
rd3视网膜变性基因先前被定位在小鼠1号染色体（Chr）上Akp1基因远端10±2.5厘摩（cM）处（Chang等人，1993年），该区域可能与人类USH2A基因座同源，USH2A基因携带导致Usher IIa型视网膜变性/听力丧失综合征的突变。构建了Rb(11, 13)4Bnr(rd3/rd3)×C57BL/6J杂交组合的回交群体，分析了428个F2减数分裂，将rd3基因定位在标记D1MIT292/D1MIT209和D1MIT510之间，距离为1.40±0.57厘摩。这些侧翼标记和USH2A的小鼠直系同源基因（Mush2a）被定位在T31小鼠辐射杂种（RH）板上，结果是D1MIT292/D1MIT209和D1MIT510相距7.9厘摩（约800千碱基对），而Mush2a在这对标记近端大于30厘摩，将其排除在rd3基因座之外。生成了一个跨越rd3基因座的重叠群，由2个酵母人工染色体（YAC）和1个细菌人工染色体（BAC）组成，其中不存在Mush2a，证实其被排除在该基因座之外。比较怀特黑德遗传图谱和我们的遗传图谱中相邻的标记对，发现标记顺序和遗传距离存在一些差异。比较我们的遗传图谱和RH图谱，发现遗传距离和物理距离之间存在一些高度偏斜的关系。
