Objective: To study the preparation and application of cells used in the external quality assessment of chromosome karyotyping and use the cells in the external quality assessment.
Methods: After diagnosis of cytogenetics or molecular genetics, and the delivery of diagnostic reports, residual living cells adhered to the culture flask with uncommon and complicated chromosomal abnormalities which were likely to be misdiagnosed were collected. Cells were collected after multiple cell passaging or superfluous cells were collected as the procedure for passaging cells was ongoing. Cells with chromosomal abnormalities of the same kind or the same case which were collected at different time were preserved together after the preparation of cell suspension and fixation of cells. Then cells were mixed together in different proportions and species according to the requirements of the external quality assessment, obtaining different ratios of mixed cell suspensions of cells with abnormal chromosomes and chimeric karyotypes. The cell suspensions were stored for the external quality assessment of chromosome karyotyping.
Results: Cell suspension which contained chimera with 4 types of abnormal chromosome karyotypes was prepared during the trial-produce. The karyotypes contained in the chimera were 46, xy, t (1;20) (q32;p21), 46, xx, t (13;14) (q10;q10), 45, xx, t (13;22) (q10;q10), and 47, xx, +mar. The cell suspension can be delivered to the laboratories and used in the external quality assessment.
Conclusion: The preparation of cells with abnormal chromosomes and chimeric karyotypes and their application in the external quality assessment of chromosome karyotyping make it possible to evaluate chromosomes prepared by laboratories, and to assess the accuracy of diagnosis of chromosome structures and abnormal chromosomes as well as the ratio of the chimeras by laboratories at the same time. It is a feasible method of the external quality assessment.