BACs-on-beads: a new robust and rapid detection method for prenatal diagnosis

Abstract

Karyotyping, the gold standard used for diagnosis of chromosomal abnormalities, is being progressively replaced by rapid aneuploidy testing (RAT) techniques such as quantitative fluorescence-PCR, FISH and multiplex ligation-dependent probe amplification for diagnosing the common aneuploidies or chromosomal microarray analysis for comprehensive genome-wide testing. However, due to technical limitations, current RATs are confined to the detection of common aneuploidies 13, 18, 21 and sex chromosomes. To overcome the limitations of RATs, a bacterial artificial chromosomes-on-beads (BoBs™) assay technology has been introduced for the detection of the common aneuploidies as well as specific microdeletion syndromes. The BoBs assay is a bead-based multiplex assay using polystyrene beads impregnated with two spectrally distinct infrared fluorochromes to create a liquid array of up to 100 unique spectral signatures that supports the analysis of that scale of simultaneous hybridization assays on a minute DNA sample. This review gives an overview on the collective experiences of BoBs applications in prenatal diagnosis.

Keywords::

• BACs-on-beads
• POC
• prenatal diagnosis
• RAT

Acknowledgements

This work was partially supported by the Direct Grant for research, the Chinese University of Hong Kong and the Health and Medical Research fund from the Hong Kong Government.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Traditional karyotyping is the gold standard, but it is a labor-intensive method that requires days for cell culture to yield active cells for analysis. It will be progressively replaced by rapid aneuploidy testing as well as chromosomal microarray analysis.

• Clinical needs drive the investigation of the high-throughput, multiplexed, quantitative and cost-effective new methods for prenatal diagnosis.

• Bacterial artificial chromosomes-on-beads (BoBs) platform creates a liquid array of up to 100 different dye/bead combinations with unique spectral signatures and supports that scale of simultaneous hybridization assays on a minute DNA sample.

• BoBs assay provides rapid, accurate results and yields important additional information beyond that obtained by the other rapid aneuploidy testing, such as FISH and quantitative fluorescence-PCR.

• A negative result by BoBs does not fully exclude any of these syndromes, as there are other etiological bases for these disorders that are not covered in this platform.

• False-positive and false-negative rates of BoBs are estimated to be approximately 0.2 and 1–3%, respectively.