X-连锁迟发性脊椎骨骺发育不良家系SEDL基因突变研究

目的：确定中国汉族中一个X－连锁迟发性脊椎骨骺发育不良（spondyloepiphyseal dyskplasia 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GenBank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（Ⅳ15、Ⅴ3）SEDL基因第2内含子剪接受体处发现了IVS2－2A→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IVS2－2A→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，有重要的临床价值。

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

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.