A new study assessed droplet digital polymerase chain reaction (ddPCR) as an alternative diagnostic tool to allele-specific oligonucleotide real-time quantitative PCR (ASO-qPCR) to detect the D816V KIT mutation in patients with suspected systemic mastocytosis (SM). The study, published in Clinical Lymphoma, Myeloma & Leukemia, found that ddPCR could reliably detect the mutation in a noninvasive manner in peripheral blood.

One of the minor criteria for diagnosing SM is the detection of the D816V KIT mutation in the bone marrow, which is precise but invasive. ASO-qPCR is a sensitive and noninvasive method that has demonstrated the ability to detect the mutation in bone marrow in 92% of cases of indolent SM with skin lesions and in 66% of cases without skin lesions.

However, commercial kits for ASO-qPCR are not readily available and the method is not standardized.

The research team assessed the utility of a noninvasive, commercially available ddPCR assay to detect and quantify the D816V KIT mutation in patients with suspected or confirmed SM. To evaluate specificity and determine the limit of blank, samples of peripheral blood from 30 healthy donors were assessed. In parallel, 35 samples from patients with suspected or confirmed SM were analyzed by both ddPCR and ASO-qPCR.

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Sixty matched peripheral blood and bone marrow samples were analyzed to determine the concordance between ddPCR results in the bone marrow and peripheral blood.

The results revealed a very high concordance between ddPCR and ASO-qPCR in detecting and quantifying the KIT D816V mutation in both peripheral blood and the bone marrow, and no mutation was detected in any of the healthy donors.

The authors concluded, “ddPCR is an attractive alternative to ASO-qPCR for KIT D816V mutation detection and quantification in SM and may reliably detect the D816V mutation non-invasively in [peripheral blood] in patients with suspected SM.”

Reference

Monaldi C, de Santis S, Mancini M, et al. MPN-182 droplet digital PCR for non-invasive detection of the KIT D816V mutation in the peripheral blood of patients with suspected systemic mastocytosis. Clin Lymphoma Myeloma Leuk. Published online September 21, 2022. doi:10.1016/S2152-2650(22)01442-2