目的针对致死性侏儒症I型（thanatophoric dysplasia typeⅠ,TD-Ⅰ）FGFR3基因的突变热点＂p.R248C＂,建立快速特异的酶切鉴定法（restriction endonuelease testing,RE）和扩增受阻突变系统（amplification refractory mutation system,ARMS）/RE法,并应用于后续3例疑似TD-I高危胎儿的快速产前诊断,以及时防止患胎出生,同时为今后的胚胎植入前遗传学诊断（preimplantation genetic diagnosis,PGD）打下良好基础。方法首先,针对突变热点p.R248C突变前后的序列特点,选择合适的内切酶＂Afe I＂,建立酶切鉴定法。其次,设计双错配碱基特异引物结合Apa LI酶切,建立ARMS/RE双重特异鉴定法。对阴性和阳性结果均再用普通引物扩、测的结果进行验证。结果用Afe I酶切FGFR3基因exons（6-7）普通引物的PCR产物（535 bp）,正常对照及非p.R248C突变的TD病例均能被切成255 bp和280 bp 2个片段,而胎1~胎3均切出255 bp、280 bp和535 bp 3个片段。用特异引物E7（p.R248C）扩增,正常对照和非p.R248C突变的TD病例均扩增阴性,无法进一步做酶切鉴定;而p.R248C突变均扩增阳性,当再用Apa LI酶切PCR产物（365 bp）时,胎1~胎3均切出22 bp和343 bp 2个片段。通过引物扩、测结果显示：胎1~胎3均是p.R248C杂合突变。结论该法快速特异、准确可靠,可用于p.R248C突变热点的快速检测及含该突变高危胎儿的快速产前诊断。该法还可用于含p.R248C突变TD-I型家系的PGD。胎1~胎3都是TD-I患胎,建议尽早终止妊娠。Objective To build up the specific rapid methods of RE and ARMS/RE for mutation hotspot＂p.R248C＂in the FGFR3 gene of thanatophoric dysplasia type I（TD-I）,then use the method for rapid prenatal diagnosis of 3 follow-up high-risk fetuses of TD-I to stop the birth of suffering fetuses,at the same time,lay a good foundation of preimplantation genetic diagnosis（PGD） for the future.Methods First,according to the characteristics of the sequence of the mutation hot spot p.248 C before and after mutation,the appropriate enzyme＂Afe I＂was selected to establish the identification method of enzyme digestion.After that,specific primers of double mismatch bases were devised,combining the method of digestion of Apa LI（ARMS/RE） to achieve the double identification.In the end,the sequences obtained by common primers were used to verify the negative and positive results through DNA sequencing.Results For the normal control and the patient without p.R248 C mutation of TD-I,PCR products（535 bp） of exons（6-7） of FGFR3 gene,amplified by common primers,could be digested into 2 fragments（255 bp and 280 bp） by Afe I.However,for fetuses 1~3,the PCR products could be digested into 3 fragments（255 bp,280 bp and 535 bp）.The normal control and the patient without p.R248 C mutation of TD-I were negative using the specific primers E7（p.R248C）,which could not be further identified by enzyme digestion.For the fetuses with p.R248 C mutation of TD-I,PCR products（365 bp） of exon 7 of FGFR3 gene,amplified by specific primers,could be digested by Apa LI and all the digested products were 22 bp and 343 bp.Sequencing results of common primers＇ products indicated：fetuses 1~3 were p.R248 C heterozygous mutation.Conclusions The method is fast,accurate and reliable,which can be available for the fast detection of mutation hot spot p.R248 C and the rapid prenatal diagnosis of high-risk fetus with p.R248 C mutation.This method can also be applied to PGD of high-risk fetus of TD-I with the mutation＂p.R248C＂.Fo闽粤合作科研基金（71010025
