目的：至今已有多种筛查和诊断脆性X综合征(fragile X syndrome,FXS)的方法,以PCR法和Southern印迹方法应用最广，然而每种方法均存在各自的局限性。该研究探讨发根脆性X智力低下蛋白（fragile X mental retardation protein，FMRP）检测在诊断或筛查FXS中的可靠性，以建立一种快速、简便、价廉且可靠的诊断FXS的方法。方法：采用发根FMRP免疫组化的检测方法对80例健康儿童、40例不明原因智力低下儿童、已确诊FXS家系成员12例进行检查; 用7-deza-dGTP PCR 法进行对照，探讨其对诊断FXS的应用价值。结果：在80例健康儿童中，发根FMRP的表达率均在80%以上。40例不明原因智力低下患儿中，2例确诊为FXS患儿的发根FMRP表达率分别为10%和0，另38例非FXS患者发根FMRP的表达率均在80%以上。在FXS家系调查中，确诊的2例FXS患者的发根FMRP表达率均为0。结论：发根FMRP检测诊断FXS具有快速、简便、价廉、可靠等特点，值得进一步推广应用。［中国当代儿科杂志，2009，11（10）：817-820］

OBJECTIVE: Fragile X syndrome (FXS) may be identified by many methods, such as PCR assay and Southern blot. However, each method has its limits or shortcomings. This study explored the reliability of the rapid, convenient and inexpensive hair root fragile X mental retardation protein (FMRP ) assay in the identification of FXS. METHODS: FMRP in hair roots was determined by immunohistochemistry assay in 80 healthy children, in 40 children with mental retardation of unknown etiology and in 12 family members in one pedigree of FXS. FXS was confirmed by 7-deza-dGTP PCR. RESULTS: There was a high expression of FMRP in hair roots (≥80%) in healthy children. Two children were confirmed with FXS by 7-deza-dGTP PCR in 40 children with mental retardation of unknown etiology. FMRP expression was 10% and zero respectively in the two children. The other 38 children had FMRP expression of more than 80%. FMRP was not expressed in the two cases of FXS from the pedigree of FXS. CONCLUSIONS: Inexpensive, rapid and convenient hair root FMRP assay is reliable for the diagnosis of FXS and may be widely applied for screening and diagnosing FXS in children with mental retardation.［Chin J Contemp Pediatr, 2009, 11 (10):817-820］