X-连锁迟发性脊椎骨骺发育不良SEDL基因剪接受体突变导致潜在剪接位点激活(英文)

Mutation of acceptor splice site of the SEDL gene in X-linked spondyloepiphyseal dysplasia tarda causes the activation of cryptic splice site

目的深入研究X连锁迟发性脊椎骨骺发育不良(Xlinkedspondyloepiphysealdysplasiatarda,SEDL)的发病机理,为最终防治本病提供依据。方法应用逆转录PCR及克隆测序方法对1例涉及SEDL基因第5内含子剪接受体缺失的SEDL患者进行mRNA表达研究。结果该患者存在2个不同片段长度的mRNA表达产物,与GenBank正常序列进行BLAST比较后发现,393bp的表达产物是第6外显子内一个新的潜在剪接位点激活后形成的产物;433bp的表达产物与8号染色体的部分基因组序列完全一致。结论SEDL基因第5内含子剪接受体位点及其后的第6外显子共13个碱基的缺失突变导致第6外显子内一个新的潜在剪接受体位点激活,使转录后的mRNA丢失了第6外显子内47bp的编码序列,并使紧接其后的2个密码子产生移码,导致翻译的提前终止(D109-S123del;S124fsX126)。另外,该突变可能激活了8号染色体上假基因SEDLP2的转录,从而部分地补偿了SEDL蛋白的功能。

Objective To further investigate the genetic basis of hereditary X-linked spondyloepiphyseal dysplasia tarda (SEDL) and provide useful information for the prevention and treatment of the disease. Methods RT-PCR and cDNA sequencing were used to test mRNA expression of SEDL gene in a patient with 13 bp deletion of SEDL gene involving the acceptor splice site of intron 5. Results Of two different sizes of mRNA products identified in the patient, the 393 bp product was created due to the activation of cryptic splice site within exon 6; the 433 bp product was completely consistent with the part of genomic sequence on chromosome 8. Conclusion The intragenic deletion that occurred in the acceptor splice site of the 3′ region of intron 5 and the 5′ coding region of exon 6 results in the activation of a cryptic splice site within exon 6, which causes 47 bp deletion of the resulting mRNA followed by a frameshift that would add two missense amino acids and then be followed by a termination codon (D109-S123del; S124fsX126). In addition, the mutation may activate the transcription of pseudogene SEDLP2 on chromosome 8 to partly complement the function of SEDL protein.