FMRP检测在儿童脆性X综合征中诊断价值的实验评价

目的对脆性X智力低下蛋白（fragile X mental retardation protein，FMRP）免疫细胞化学诊断方法并进行临床流行病学评价；利用ROC曲线确定适合本地筛查脆性X综合征的外周血淋巴细胞FMRP免疫组化法的诊断临界点。方法对临床拟诊为不明原因智力低下的的41例不明原因的智力低下患儿，同时进行免疫细胞化学方法进行外周血淋巴细胞FMRP表达检测和7-deza—dGTP PCR法两种方法检查，以目前较为公认的7-deza—dGTP PCR法为诊断金标准，对外周血淋巴细胞FMRP细胞免疫组化法（SP法）进行实验评价，计算其灵敏度、特异度、阳性似然比、阴性似然比等统计学指标。采用ROC曲线确定适合本地筛查脆性X综合征的外周血淋巴细胞FMRP表达率的诊断临界点。结果41例不明原因智力低下患儿中染色体核型分析均正常，其中染色体脆性位点检查异常的1例，约为2．4％。7-deza—dGTP PCR法诊断FXS患者11例，约占26．2％，其中男9例，女2例；ROC计算得出最佳的外周血淋巴细胞FMRP表达率的诊断临界点为46％，灵敏度为90．9％，特异度为93．5％。结论外周血淋巴细胞FMRP免疫细胞化学检测是一种可靠的FXS诊断和筛查方法，具有快速、简便、廉价、相对无创伤性等优点，可进行大样本筛查及标本邮寄快递检测，适宜在我国基层开展早期FXS患者诊断和筛查。

Evaluation of peripheral blood lymphocyte FMRP detection for diagnosing fragile X syndrome in children

Objective： To evaluate a laboratory diagnostic method for fragile X syndrome by clinical epidemiology, and to identify the cut - off point of the fragile X mental retardation protein （FMRP） expression rate for diagnosing fragile X syndrome by receiver operating characteristic curve （ROC）. Methods ： Forty - one children with mental retardation of etiology unknown were determined by FMRP immuocytochemistry and 7 - deza - dGTP polymerase chain reaction （PCR） at the same time. 7 - deza - dGTP PCR was choosed as golden stardard for FXS. The cut - off point of FMRP expression rate for diagnosing FXS was defined by ROC. Results ： All chromosome karyotype of 41 children with mental retardation were normal, but there was a patient with abnormal chromosome fragile site, accounting for 2.4%. Among 11 children with FXS diagnosed by 7 - deza - dGTP PCR diagnosis, there were 9 male full mutation, 2 femal full mutation. The cut -off point of FMRP expression rate for diagnosing FXS was defined as 45% by ROC. Conclusions： FMRP test in peripheral blood lymphocytes is a sort of reliable, quickly, convenient, cheap diagnostic and screening method. In addition, it possess relative traumatic occlusion merit, and may to screen large sample or detection by sample expressage. Carry to earlier period diagnosis and screen FXS full mutation patient from the mental retardation patient in basic level hospital.