Turner综合征患者标记染色体的鉴定与分析

目的 分析11例携带标记染色体的Turner综合征患者的核型,研究这类染色体的表型效应。方法 选择11例具Turner综合征表型的患者,常规核型分析均显示为携带标记染色体的嵌合体,其中6例标记染色体呈环状。患者G带核型表示为mos．45,X／46,X,＋mar或者mos．45,X／46,X,＋r．以X／Y着丝粒探针,应用荧光原位杂交（FISH）技术分析这些标记染色体起源,对其中2例较大的环状染色体,结合反向染色体涂染确定断裂位点,比较不同断裂位点的标记染色体的遗传学效应。结果11例患者所携带的标记染色体均为环状染色体,r（X）的断裂位点分别位于Xp22、Xq22、Xq24、Xq26等。结论 Turner综合征患者的标记染色体主要来源于X染色体,且表现为r（X）形式。r（X）均以嵌合型的形式存在。

Identification and characterization of marker chromosome in Turner syndrome

OBJECTIVE: To analyze the karyotypes of 11 cases of Turner syndrome with marker chromosome, and study the phenotypic effects resulting from the abnormal karyotype. METHODS: Eleven Turner syndrome patients had a mosaic karyotype and carried a marker chromosome, and 6 marker chromosomes were ring chromosomes. Their karyotypes were showed as mos. 45, X/46, X, + mar or mos. 45, X/46, X, + r. Fluorescence in situ hybridization (FISH) technique with X/Y centromere probes was performed to determine the origin of the marker chromosome. Reverse chromosome painting technique was used to identify the breakpoints of two largest markers. Phenotype effects with different chromosome breakpoints were compared. RESULTS: All the 11 marker chromosomes were ring X chromosomes. The breakpoints of the r(X) were involved in Xp22, Xq22, Xq24 and Xq26, etc. CONCLUSIONS: The marker chromosomes in Turner syndrome mainly originate from X chromosome and form ring chromosome X. Each r(X) in our patients was mosaic, indicating it was originated from mitosis error during early embryo development. To analyze the origin of the marker chromosome and the breakpoint of r(X) will provide guidance for the therapy and prognosis of the Turner syndrome patient.