Objective To detect the genetic deletion /duplication with 22q11.2 from the peripheral blood in the patients with 22q11.2 deletion syndrome by using multiple ligation - dependent probe amplification { MLPA) and fluorescent in situ hybridization ( FISH), and to analyze the predictive value of these two techniques in diagnosis of 22q11.2 deletion syndrome. Methods FISH was conducted in the meta-phase chromosomes to detect whether a patient with congenital heart disease had microduplication/ microdeletion in the 22q11. 2 region. MLPA was used to determine the microduplication/ microdeletion realm from the patient and his parents. Results The result of FISH showed that the DiGeorge/VCFS N25(D22S75)probe hybridization signal of the patient disappeared in one chromosome of 22q11.2,while the result of MLPA showed that the fluorescence peak of those 6 probes associated with 22q11. 2 deletion syndrome of the patient were much lower than the normal controls. The phenotype of the patient included heart malformation only, and this was not in accordance with the genotype. Conclusions Combination of MLPA and FISH can detect the microdeletion of chromosome 22q11.2 more precisely. Clinical symptoms are not directly in accordance with the deletion realm in 22q11.2 microdeletion syndrome.%目的 分别采用多重连接探针扩增技术(MLPA)与荧光原位杂交技术(FISH)对22q1 1.2微缺失综合征外周血标本患者基因缺失/重复突变的类型及变异范围进行检测,分析在22q11.2微缺失综合征诊断中二者联合应用的诊断价值.方法 采集1例仅心脏异常患儿及其父母外周血,取200 μL外周血提取DNA后采用MLPA技术对患儿及其父母的染色体22q11.2缺失的范围进行检测,取外周血1 mL进行培养,采用DiGeorge/VCFS N25(D22S75)的FISH探针对培养后的中期淋巴细胞进行杂交.结果 患儿淋巴细胞分裂中期细胞应用FISH技术检测结果为22号染色体上的DiGeorge/VCFS N25(D22S75)区杂合性缺失；MLPA验证结果显示患儿与22q11.2微缺失综合征相关的6个探针对应的片段大小位置在3100的电泳图上荧光峰值相比健康对照明显出现减半,其父母亲均在正常范围.患儿的临床表现仅有先天性心脏病,无其他异常,与其基因缺失片段长度(2.0 Mb)极不相称.结论 联合应用FISH和MLPA检测22q11.2微缺失综合征,可以明显提高诊断的准确性.22q11.2微缺失综合征的临床表现与基因缺失片段的长度无相关性.
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