X-连锁迟发性脊椎骨骺发育不良家系SEDL基因突变研究

Identification of a novel mutation IVS2-2A→C of SEDL gene in a Chinese family with X-linked spondyloepiphyseal dysplasia tarda

目的 确定中国汉族人中一个 X-连锁迟发性脊椎骨骺发育不良 (spondyloepiphyseal dyspla-sia tarda,SEDL)大家系 SEDL 基因突变类型 ,探讨 SEDL 发病的分子基础。方法 用聚合酶链反应扩增产物双向直接测序方法检测了患者构成 SEDL 基因可读框的第 3～ 6外显子及相邻侧翼区的 DNA序列 ,将测序结果与 Gen Bank公布的 SEDL基因正常序列对比找出突变。然后在家系其他成员中证实该突变。结果 在 2例患者 ( 1 5、 3) SEDL 基因第 2内含子剪接受体处发现了 IVS2 - 2 A→ C突变 ,4个外显子的核苷酸序列未见改变。该突变在 4例女性携带者得到证实 ,她们的基因型表现为野生型与突变型杂合现象。家系中 2名未受累男性和 15名无关健康个体未检测到这一突变。在该家系还检测出 4个无症状的携带者。结论 首次发现 SEDL 基因 IVS2 - 2 A→C突变。该突变引起 SEDL基因第 2内含子 3′端剪接受体改变 ,使之不能与外显子 3正常剪接 ,可能是 SEDL 发病的分子基础。检测该突变可进行基因诊断 。

Objective To identify the mutation of spondyloepiphyseal dysplasia tarda (SEDL) gene in a large Chinese family with X linked spondyloepiphyseal dysplasia tarda and to make a discussion on the pathogenesis of SEDL at the molecular level. Methods In two patients, four exons comprising the SEDL open reading frame as well as their exon/intron boundaries were analyzed by bi directional direct sequencing of PCR products.The sequencing results were compared against the normal sequences in GenBank to find the mutation.Then the mutation was identified in other members of the family. Results A nucleotide substitution of the splice acceptor in SEDL intron 2, IVS2 2A→C ,was detected in two affected individuals(Ⅳ 15 ,Ⅴ 3) in the Chinese family with SEDL, but no sequence change occurring on exons 3 6 was detected. The transversion was also identified in four heterozygous carriers. The mutation was not found in two unaffected male individuals and fifteen normal controls. Furthermore, four potential carriers were identified in the family. Conclusion The mutation IVS2 2A→C of SEDL gene was firstly determined in the world.The change of the splice acceptor in SEDL intron 2 may cause skipping of exon 3,which is responsible for the disease. Molecular diagnosis can be made by detecting the mutation.