一例21号环状染色体综合征的细胞遗传学和表型定位分析

目的通过对1例21号环状染色体综合征患者的细胞遗传学分析，探讨21号环状染色体的形成原因，临床表型与染色体区带的关系。方法应用染色体G带、C带、N带、高分辨显带和荧光原位杂交技术对21号环状染色体进行识别与定位。结果患儿双亲核型正常，患儿核型为46，XY，r（21）91]／46，XY，r（21；21）（p11q22．3；p11q22．3）5]／45，XY，-214]。结论21号环状染色体综合征的临床表现与21q末端缺失的多少相关，男性性别发育异常可能与21q22．3片段的缺失相关。

Cytogenetic analysis and phenotype location analysis on the karyotype of a ring chromosome 21 syndrome

Objective To search the forming cause and the correlation between the clinical phenotype and chromosome band by the cytogenetic analysis on a case of ring chromosome 21 syndrome. Methods Identification and location of 21 ring chromosome were performed with the G-banding, C-banding,N-banding,high-resolution banding and fluorescence in situ hybridization(FISH) techniques. Results It was found that the karyotypes of the patient' s parents are normal. The patient's karyotype is 46,XY,r(21)91/46,XY,r(21;21)(p11q22.3;p11q22.3)5/45,XY,-214. Conclusion The clinical phenotype of ring chromosome 21 syndrome is related to the deletion of distal segment of 21q, and the abnormal sexual development of male is related with the deletion of 21q22.3.