联合运用多种技术鉴别四例胎儿新发标记染色体

目的探讨传统细胞遗传学技术联合SNP - array （ single nucleotide polymorphisms array, SNP - array）在识别胎儿微小额外标记染色体（ supernumerary marker chromosome, sSMC）致病性中的临床应用价值。方法通过常规G显带技术分析胎儿染色体核型，针对发现的sSMC，应用C显带技术分析ssMC，如果sSMC非异染色质，进一步进行SNP—array辨别其来源并分析相应的表型。结果通过对8575例产前诊断标本G显带核型分析发现4例新发标记染色体，其中C显带示2例为异染色质结构，2例为非异染色质结构。这2例非异染色质结构病例进一步行SNP—array检测，结果示一例未见致病性改变，另一例为4号染色体部分重复。结论SNP—array能够在基因组水平上识别胎儿sSMC的成分，结合传统的细胞遗传学技术应用于产前诊断中，为确定sSMC的致病性提供了可靠的产前诊断技术平台。

Combined various techniques to identify de novo marker chromosome in 4 fetus.

Objective： To explore the clinical application of Single Nucleotide Polymorphisms array （SNP- array） and cytogenetic techniques in the prenatal evaluation of fetal with supernumerary small marker chromosome （sSMC）. Method： G - banding were perform on all prenatal diagnosis from amniotic fluid and cord blood sample. C banding techniques was used to analyze the sSMC structure. SNP - array was used to analyze the origin and phenotype of the sSMC. Results ： In 8575 prenatal diagnostic specimens through the G - banding karyotype detection, 4 cases were de novo sSMC. C - banding identify 2 cases as a source of heterochromatin, 2 cases were non - source of heterochromatin which were further tested by SNP - array, results shown that one case had no pathogenic genomic change and the other case＇s sSMC chromosome comes from the 4th chromosome. Conclusion： SNP -array is an important method to detect the origin of sSMC. Combined with the traditional karyotype analysis in prenatal diagnosis, it provides a valuable prenatal diagnosis technique platform for characterizing the structure of the sSMC.