1例9p缺失综合征伴20q12-13.33重复患儿的遗传学分析

Genetic analysis of a child with 9p deletion syndrome and 20q12-13.33 duplication

目的探讨9p缺失综合征伴20q12-13.33重复的临床特征及细胞分子遗传学特点。方法运用常规G显带分析1例患儿及父母外周血染色体核型改变并结合低深度全基因组测序(CNV-seq)对患儿的核型分析结果进行精准定位。结果患儿CNV-seq结果:9号染色体p24.3-24.1区域缺失5.74 Mb大小(chr9:200000-5940000),20号染色体q12-13.33区域重复23.04 Mb大小(chr20:39880000-62920000)。该患儿母亲染色体改变为9p24和20q13.1-q13.3的平衡插入易位,患儿分别继承了母亲的9号染色体和20号染色体,最终结合CNV-seq结果明确了该患儿的异常核型。结论9p缺失综合征及20q12-13.33重复是该患儿异常表型的主要原因,将细胞遗传学检测方法与分子遗传学检测方法结合起来可以帮助明确易位的性质及溯源异常染色体的来源,有利于再发风险的评估,与单一的细胞遗传学分析方法相比,CNV-seq技术在染色体拷贝数变异中具有更高的分辨率和准确性。

Objective To explore the clinical features and cytomolecular genetics of 9p deletion syndrome with 20q12-13.33 duplication.Methods The karyotype changes in the peripheral blood of one child and their parents were analyzed by conventional G-banding analysis,and the karyotype analysis results were accurately located in combination with low depth whole genome sequencing(CNV-seq).Results he results of CNV-seq showed that the deletion of region p24.3-24.1 on chromosome 9 was 5.74 Mb(chr9:200000-5940000),and the duplication of region q12-13.33 on chromosome 20 was 23.04 Mb(chr20:39880000-62920000).The mother of the child had a balanced insertion translocation of 9p24 and 20q13.1-q13.3,and the child inherited chromosome 9 and chromosome 20 from the mother,respectively.Finally,the abnormal karyotype of the child was confirmed by CNV-seq results.Conclusion 9p deletion syndrome and 20q12-13.33 duplication are the main reasons for the abnormal phenotype of the patient.Combining cytogenetic testing methods with molecular genetics testing methods can help to clarify the nature of translocation and trace the source of abnormal chromosomes,which is conducive to the assessment of recurrence risk.Compared with a single cytogenetic analysis method,CNV seq technology has higher resolution and accuracy in chromosome copy number variation.