摘要目的 用多重连接探针扩增技术(MLPA)和微阵列比较基因组杂交技术(array-CGH)研究4例以运动、智力发育落后为主要表现的患儿甲基化CpG结合蛋白2基因(MECP2)基因突变特点.方法 取北京大学第一医院2012年6月至2014年4月收治的4例患儿及其中例2、例4母亲的外周血,提取基因组DNA;先对患儿用MLPA方法进行微缺失和微重复检测,然后用array-CGH进行分析进一步确定重复片段的大小;同时对2例患儿的母亲进行array-CGH和X染色体失活分析(XCI).结果 4例患儿均表现为严重肌张力低下,运动、智力发育落后和语言发育障碍,除例2之外,另3例患儿婴儿期均反复发生肺炎.MLPA显示4例患儿均存在染色体Xq28重复;array-CGH检测显示4例患儿Xq28区域存在重复,4例患儿重复片段大小分别为14.931 Mb、0.393 Mb、0.482 Mb、0.299 Mb,经与UCSC(http://genome.ucsc.edu/)数据库比对,4例患儿的重复片段均包含MECP2和宿主细胞因子C1基因(HCFC1).例2和例4患儿的母亲存在Xq28重复,其中例4患儿母亲的重复片段起止位点和大小与患儿完全相同,例2母亲重复片段为0.343 Mb,小于患儿,近着丝粒断点与患儿不同,远端断点与患儿相同.X染色体失活分析发现母亲二条X染色体活性比例为0∶100,存在重复的一条X染色体完全失活,并且将发生重复的这条X染色体遗传给了患儿.结论 对于运动智力发育落后、肌张力低下、语言发育障碍和反复发生感染的患儿进行MLPA和array-CGH联合检测是诊断MECP2重复综合征的有效且特异的方法.

abstractsObjective To investigate whether the four boys with delayed motor development and intellectual disability suffer from MECP2 duplication syndrome.Method Blood specimens and clinical data of four patients and mothers of patient 2 and patient 4 were collected.Genomic DNA was extracted from peripheral blood using DNA extraction kit.At first multiplex ligation-dependent probe amplification (MLPA) was employed in 4 patients,two distinct kits SALSA P036 and P070 for sub-telomere screening,and SALSA P245 for the 22 common microdeletion and microduplication syndromes.Then array-CGH analysis was carried out.Two mothers of patients were tested by array-comparative genomic hybridization (CGH) and X chromosome inactivation analysis.Result All the 4 patients presented with severe hypotonia,delayed motor development,intellectual disability and absent or limited language.Three patients manifested recurrent pneumonia in infancy except patient 2.Four patients had duplication on chromosome Xq28 with MLPA kit SALSA P245.Array-CGH identified the size of each duplication on Xq28.The precise size of each duplication was different in the four patients:patient 1,14.931 Mb,patient 2,0.393 Mb,patient 3,0.482 Mb and patient 4,0.299 Mb.To compare Xq28 duplications with UCSC database (http://genome.ucsc.edu/) revealed that each duplication harbors the MECP2 and HCFC1 gene.Mothers of patient 2 and patient 4 also carried microduplication on Xq28.X chromosome inactivation analysis demonstrated completely skewed inactivation (0∶ 100) and it is the inactive allele that passed on to the patients.Conclusion For patients that present with delayed motor development,intellectual disability,hypotonia,absent or limited language and recurrent infection,combination of MLPA and array-CGH is effective and specific diagnostic methods of MECP2 duplication syndrome.