Research On The Diagnosis Of Unbalanced Chromosome Aberrations Through High-throughput Sequencing

Unbalanced chromosome aberration is an important cause of human birth defects. Prenatal genetic diagnosis is believed to be the most efficient prevention strategy of these chromosome abnormalties. However, due to the poor resolution of(> 5-10 Mb), the most frequently used chromosomal G-banding karyotype analysis can not detect submicroscopic unbalanced chromosome aberrations which usually lead to human diseases. Though the array CGH is able to detect chromosome micro-deletion/duplication efficiently, they are expensive and system-closed monotechnics, reducing their clinilcal value. Massively parallel sequencing(MPS) has the advantage of high throughput single molecule sequencing, and is supposed to be able to diagnose genomic copy number variations according to its unique sequencing features. In this study, to investigate the feasibility and clinical value of LD-MPS in the CNVs detection, we performed LD-MPS analysis on 47 samples of unbalanced chromosome aberrations. Results from our study suggested LD-MPS would be a powerful technique for the prevention of birth defects due to unbalanced chromosome aberrations.Objective: To investigate the value of the LD-MPS in detecting unbalanced chromosome aberrations, and establish an effective diagnostic platform for detecting the chromosome aberrations by combining multiple molecular diagnosis techniques.Methods: Forty-seven cases with unbalanced chromosme aberrations were chosen from a chort of 392 cases referred to Nanjing Maternity and Child Health Care Hospital for genetic counseling during January 2010 to March 2013. Sequencing were performed on the 47 cases using Illumina Hi Seq2000 sequencer with a sequencing set of 50 bp read length, paired-end and 2× reads depth. Array CGH, FISH and MLPA were applied in some cases to verify the accuracy and sensitivity.Results: A total of 68 CNVs were revealed by array CGH in 47 samples, of which 24 CNVs were longer than 10 Mb in size, 32 were 1-10 Mb and 12 were shorter than 1Mb. All of the 47 samples were successfully analyzed by sequencing. LD-MPS detected 67 CNVs, including 24 CNVs longer than 10 Mb with a consistency rate of 95.83% in size with results from array CGH; 31 CNVs were 1-10 Mb with a consistency rate of 96.87%; 12 CNVs were smaller than 1 Mb and the consistency rate was 100%. Two inconsistent cases were further vertified to be a partial trisomy and a mosaic.Conclusion: As a novel molecular detection technology, LD-MPS provides another method for fast, accurate diagnosis of genome-wide unbalanced chromosome aberrations.