Fig. 2

Increased variability in low cell input. Increased dispersion of heterozygous allele frequencies is observed with low cell input (a). The range cannot be determined exactly in one and two cell assays due to threshold cut-offs, but extend from at least 10 to 90%, and are heavily affected by noise. The effect of variable read depths is observed from chromosomal allele frequencies, which makes copy gains, resolved from approximately 50 cells (b), difficult to detect, when approaching the single cell level (c). This effect is also demonstrated by normalized probability density comparison of trisomy 8 as shown in the supplement (Additional file 4: Figure S3)