Part-per-million accuracy
with low costs

ppmSeq™ for extreme SNV accuracy

The combination of Ultima’s flow-based sequencing chemistry and emulsion-based clonal amplification technologies enables a ground-breaking new method: paired plus minus sequencing, or ppmSeq™. By sequencing both strands of a captured DNA molecule, ppmSeq reduces errors to one part-per-million or better, empowering scientists to tackle the most challenging sequencing applications.​
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The frequency of these rare events is not only lower than traditional sequencing error rates, but also lower than the error rate of common sample artifacts.

Estimated tumor fraction in matched and control cfDNA samples, for standard cfDNA prep (left) and ppmSeq-mixed (right). Each column corresponds to one patient SNV profile, with one matched cfDNA sample and 9 negative control samples. Included are reads that exceed the quality thresholds of SNVQ60 for Standard, and SNVQ70 for ppmSeq-mixed.

Unique chemistry for SNVs
Our unique flow-based chemistry inherently provides advantages for calling SNVs. Our chemistry asks how many nucleotides are added, but the base identity is not a question. Incorporating one type of nucleotide per flow enables an extremely low base substitution error rate.​

SNVQ is the single nucleotide variant quality (SNVQ) score, which is different from a standard base quality score. The SNVQ score represents the error probability of the specific base substitution (e.g., A>G) rather than the aggregate error probability of any substitution (e.g., A>C/G/T).