遗传性瞳孔异位小鼠及其突变基因的染色体定位

A type of heritable ectopia pupil mouse and map of mutation gene

目的研究乙烷基亚硝基脲(ENU)诱变获得的遗传性瞳孔异位(B6-24#)小鼠的病变特征、遗传模式及突变基因在染色体上的位置。方法用瞳孔异常杂合子与正常C57BL/6(B6)小鼠配种,记录后代突变小鼠与正常小鼠数目,采用卡方检验确定遗传模式。繁殖[(B6×D2)×B6]F2及少量的[(B6×D2)F1×D2]F2突变小鼠,用平均分布于小鼠常染色体上的39个微卫星标记对突变基因进行染色体扫描,采用计算最大优势值(LODS)法判定突变基因与微卫星是否连锁并根据重组率计算突变基因的位置。结果初步诊断B6-24#为遗传性瞳孔异位,呈单基因显性遗传,外显率为85·71%。基因组扫描发现,微卫星D2Mit17与突变基因最大LODS为3·27,确定连锁。继续选用接近突变基因的D2Mit398、D2Mit259与其进行连锁分析,结果突变基因与D2Mit398、D2Mit259的重组率分别为5·45%±2·16%、0·90%±0·90%。突变基因被定位于距着丝粒约64·5cM处。在此区域附近未发现明显的候选基因。结论研究成功定位了小鼠瞳孔异位基因,有望为人类类似疾病提供一种新的小鼠模型。

Objective In previous study,we obtained a type of gene mutation mouse with pupil abnormality induced by ethylnitrosourea（ENU） Mutagenesis. Present aim was to study the heredity pattern, disease characteristics and the map of mutation gene of this type of pupil abnormality mouse （ named B6-24^# ）. Methods Heterozygous mice with abnormal pupil were mated with normal C57BL/6 mice. Their offspring with normal or mutation phenotype was registered respectively and X^2 test was used to determine the heredity pattern. The mutation gene, （ B6 × D2） × B6 F2 and some （ B6 × D2） F1 × D2 F2 mice with mutation phenotype were mapped, and 39 microsatellite markers distributed equally on the mouse euchromosome were used to scan the genome of these F2 mice. Based on the log odds score（LODS） , whether a certain microsatellite was linked to the mutation gene or not was determined and the location of mutant gene was calculated based on the recombination ratio among them. Results Lamplight examination and heredity test indicated that the B6-24# was of ectopia pupil controlled by single dominant gene with 85.71% penetrance. The mutation gene was linked to D2Mit17 in 3 cases of 30 F2 mice underwent recombination with the LODS 3.27. D2Mit398 and D2Mit259 near the mutation gene were selected to test the mutation gene,and the recombination ratio between the mutation gene and these two m icrosatellites were 5.45 % ± 2.16% and 0. 90% ± 0. 90% ,respectively. Mutation gene was mapped on chromosome 2 cM and 64.5 cM from the centromere. No obvious candidate gene was found in this region. Conclusion This research mapped a gene of mouse ectopia pupil. It may provide an new mouse model for heritable disease of human ectopia pupil.