Single cell genome analysis methods are powerful tools to define features of single cells and to identify differences between them. Since the DNA amount of a single cell is very limited, cellular DNA usually needs to be amplified by whole-genome amplification before being subjected to further analysis. A single nucleus only contains two haploid genomes. Thus, any DNA damage that prevents amplification results in loss of damaged DNA sites and induces an amplification bias. Therefore, the assessment of single cell DNA quality is urgently required. As of today, there is no simple method to determine the quality of a single cell DNA in a manner that will still retain the entire cellular DNA for amplification and downstream analysis. Here, we describe a method for whole-genome amplification with simultaneous quality control of single cell DNA by using a competitive spike-in DNA template.

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DNA sequence analysis and genotyping of biological samples using next-generation sequencing (NGS), microarrays, or real-time PCR is often limited by the small amount of sample available. A single cell contains only one to four copies of the genomic DNA, depending on the organism (haploid or diploid organism) and the cell-cycle phase. The DNA content of a single cell ranges from a few femtograms in bacteria to picograms in mammalia. In contrast, a deep analysis of the genome currently requires a few hundred nanograms up to micrograms of genomic DNA for library formation necessary for NGS sequencing or labeling protocols (e.g., microarrays). Consequently, accurate whole-genome amplification (WGA) of single-cell DNA is required for reliable genetic analysis (e.g., NGS) and is particularly important when genomic DNA is limited. The use of single-cell WGA has enabled the analysis of genomic heterogeneity of individual cells (e.g., somatic genomic variation in tumor cells). This unit describes how the genome of single cells can be used for WGA for further genomic studies, such as NGS. Recommendations for isolation of single cells are given and common sources of errors are discussed.