摘要
目的 对比分析缺失型杜氏肌营养不良症 (Duchenne muscular dystrophy,DMD)缺失热区第 46号和 51号外显子缺失后形成的连接片段的断裂点的分子结构特点 ,以研究 DMD基因外显子的缺失机理。方法 多重引物 PCR法鉴定缺失型 DMD患者 ,分别克隆第 46、51号外显子缺失后形成的连接片段 ,测定断裂点侧翼的核苷酸序列。结果 第 46号外显子缺失后 ,5′端断裂点位于 45号内含子的 AT富含区内。 3′端断裂点位于 46号内含子的中等重复序列 (medium reiteration repeats,MER1)内。连接片段有两个 bp的连接同源序列 ta,局部无小的缺失、插入和碱基的置换。第 51号外显子缺失后 ,5′端断裂点位于 50号内含子的人类类转座因子 (transposon-like human elements,THE1)序列内。 3′端短裂点位于 51号内含子 L 2序列内。连接片段有 3个 bp的连接同源序列 cta,局部无小的缺失、插入和碱基的置换。第 46、51号外显子缺失后连接片段的断裂点的二级结构分析示断裂点均位于单链发夹环的非匹配区。结论 对比第46、51号外显子缺失后形成的连接片段 ,其断裂点的共同特征是均位于重复序列 ,这些重复序列形成的单链发夹结构 ,使 DNA结构具有不稳定性 。
Objective: To study the exons deletion mechanisms for dystrophin gene, the molecular characters of breakpoints of junction fragments for deletion-type Duchenne muscular dystrophy (DMD) patients with 46 and 51 exons deletion were compared and analyzed. Methods: Deletion-type DMD patients were detected by multiplex polymerase chain reaction (mPCR). The breakpoints of junction fragments with 46 and 51 exons deletions were cloned and sequenced respectively. Results: Analysis of sequences of deletion-junction fragment of exon 46 showed that the 5′ breakpoint was located in AT-rich region of intron 45 and the 3′ breakpoint was in medium reiteration repeats (MER1) sequence. There existed 2 bp(ta) junction homology between two breakages. No small insertion, small deletion or point mutation was located near the junction point. Similarly, analysis of sequences of deletion-junction fragment of exon 51 showed that the 5′ breakpoint was located in transposon-like human elements (THE1) of intron 50 and the 3′ breakpoint was in L2 sequence. There existed 3 bp (cta) junction homology between two breakages. No small insertion, small deletion or point mutation was located near the junction point. By analyzing the secondary structure of junction fragments with 46 and 51 exons deletions, it was demonstrated that all breakpoints of junction fragments were located at the non-matching regions of single-strand hairpin. Conclusion: By comparing the junction fragments with 46 or 51 exons deletion, it was found that all of breakpoints were located in repeat sequences and the repeat sequences formed the single-strand hairpin which could make the introns instable and result in exon deletion.
出处
《中华医学遗传学杂志》
EI
CAS
CSCD
2003年第5期376-380,共5页
Chinese Journal of Medical Genetics
基金
国家自然科学基金资助项目( 3970 0 0 48
30 2 71 378)
广东省自然基金资助项目 ( 980 0 6 6
2 1 86 6 )
广东省科技攻关基金项目( 2 0 0 2 C30 6 0 3)
