The three-dimensional distances between the genes on each homologous chromosome in each cell as nuclear organization and genomic expression of the imprinted gene.

为了验证基因间空间定位对基因组功能影响的表观遗传学机制，本研究以已知的印迹区域15q11.2-q12为研究对象，测量了同一个体3种不同细胞类型中各同源染色体上SNRPN和UBE 3A基因间的三维基因间距离。 并且我们已经证明，在所有细胞类型中等位基因之间的距离显著不同（Kawamura等人，2012).此后，我们一直试图建立一种单细胞基因表达分析的RNA和DNA序列FISH方法，即从检测父系表达的SNRPN基因的RNA信号开始，依次测量同一细胞核中SNRPN-UBE 3A基因的三维距离，以证实基因三维距离的差异与SNRPN基因表达之间的直接关系。

This study is motivated to verify that gene-to-gene spatial positioning affect genomic function as epigenetic mechanism.We focused on 15q11.2-q12, one of the known imprinted region, and measured 3D inter-gene distances between SNRPN and UBE3A genes on each homologous chromosome in each cell of the three different cell types from the same individual. And we have demonstrated that the distances were significantly different between alleles in all cell types (Kawamura et al., 2012).Since then we have been trying to establish the sequential RNA and DNA FISH method as a single-cell gene expression analysis; which proceed sequentially from detection RNA signals of paternally expressed SNRPN gene to measurement of 3D distances of SNRPN-UBE3A genes in the same nucleus, in order to confirm the direct relationship between the differences of 3D distances of the genes and gene expression of SNRPN.