Malcov Mira, Naiman Tova, Yosef Dalit Ben, Carmon Ariella, Mey-Raz Nava, Amit Ami, Vagman Israel, Yaron Yuval
Sara Racine in vitro Fertilization Unit, Lis Maternity Hospital, Tel Aviv, Israel.
Reprod Biomed Online. 2007 Apr;14(4):515-21. doi: 10.1016/s1472-6483(10)60901-7.
Fragile X syndrome is caused by a dynamic mutation in the FMR1 gene. Normal individuals have <55 CGG repeats in the 5 untranslated region, premutation carriers have 55-200 repeats and a full mutation has >200 repeats. Female carriers are at risk of having affected offspring. A multiplex nested polymerase chain reaction protocol is described for preimplantation genetic diagnosis (PGD) of fragile X syndrome with simultaneous amplification of the CGG-repeat region, the Sry gene and several flanking polymorphic markers. The amplification efficiency was > or =96% for all loci. The allele dropout rate in heterozygotic females was 9% for the FMR1 CGG-repeat region and 5-10% for the polymorphic markers. Amplification failure for Sry occurred in 5% of single leukocytes isolated from males. PGD was performed in six patients who underwent 15 cycles. Results were confirmed in all cases by amniocentesis or chorionic villous sampling. Five clinical pregnancies were obtained (31% per cycle), four of which resulted in a normal delivery and one miscarried. This technique is associated with high efficiency and accuracy and may be used in carriers of full mutations and unstable high-order premutations.
脆性X综合征由FMR1基因的动态突变引起。正常个体在5'非翻译区有<55个CGG重复序列，前突变携带者有55 - 200个重复序列，而完全突变则有>200个重复序列。女性携带者有生育受影响后代的风险。本文描述了一种多重巢式聚合酶链反应方案，用于脆性X综合征的植入前基因诊断（PGD），同时扩增CGG重复区域、Sry基因和几个侧翼多态性标记。所有位点的扩增效率均≥96%。FMR1 CGG重复区域在杂合子女性中的等位基因脱失率为9%，多态性标记为5 - 10%。从男性分离的单个白细胞中，Sry基因扩增失败率为5%。对6例患者进行了15个周期的PGD。所有病例的结果均通过羊膜穿刺术或绒毛取样得到证实。获得了5次临床妊娠（每个周期31%），其中4次正常分娩，1次流产。该技术具有高效性和准确性，可用于完全突变携带者和不稳定的高阶前突变携带者。
