Detection of the KIT D816V mutation in peripheral blood of systemic mastocytosis: diagnostic implications

Abstract

Recent studies have found the KIT D816V mutation in peripheral blood of virtually all adult systemic mastocytosis patients once highly sensitive PCR techniques were used; thus, detection of the KIT D816V mutation in peripheral blood has been proposed to be included in the diagnostic work-up of systemic mastocytosis algorithms. However, the precise frequency of the mutation, the biological significance of peripheral blood-mutated cells and their potential association with involvement of bone marrow hematopoietic cells other than mast cells still remain to be investigated. Here, we determined the frequency of peripheral blood involvement by the KIT D816V mutation, as assessed by two highly sensitive PCR methods, and investigated its relationship with multilineage involvement of bone marrow hematopoiesis. Overall, our results confirmed the presence of the KIT D816V mutation in peripheral blood of most systemic mastocytosis cases (161/190; 85%) -with an increasing frequency from indolent systemic mastocytosis without skin lesions (29/44; 66%) to indolent systemic mastocytosis with skin involvement (124/135; 92%), and more aggressive disease subtypes (11/11; 100%)-as assessed by the allele-specific oligonucleotide-qPCR method, which was more sensitive (Po.0001) than the peptide nucleic acid-mediated PCR approach (84/190; 44%). Although the presence of the KIT mutation in peripheral blood, as assessed by the allele-specific oligonucleotide-qPCR technique, did not accurately predict for multilineage bone marrow involvement of hematopoiesis, the allele-specific oligonucleotide-qPCR allele burden and the peptide nucleic acid-mediated-PCR approach did. These results suggest that both methods provide clinically useful and complementary information through the identification and/or quantification of the KIT D816V mutation in peripheral blood of patients suspected of systemic mastocytosis.

Clinical presentation and management practice of systemic mastocytosis. A survey on 460 Italian patients

“…The cKIT mutation was reported in the peripheral blood of only 50% of patients, a figure significantly lower than 80% in more recent reports [26,27]. This discrepancy can be ascribed to the use of conventional methods that are not enough sensitive to detect very low cKITD816V allele burden.…”

“…Conversely, the same methodologies were able to detect the mutation in 92% of BM samples, where mutation burden is higher, in line with others' experience. Therefore, as recently suggested, standardized and highly sensitive method of detection need to be devised and implemented to allow the convenient use of peripheral blood samples as a screening tools in patients suspected to have SM [19,27,28].…”

KIT D816V–mutated bone marrow mesenchymal stem cells in indolent systemic mastocytosis are associated with disease progression

“…These findings support previous observations in advanced SM about the origin of clonal MCs in a pluripotent HPCs with the ability to differentiate to other non-MC myeloid and even lymphoid lineages. [12][13][14][15][16]45 Most interestingly, this polyclonal XCIP found across multilineage ISM cases was restricted to two-thirds of the ISM female patients carrying KIT-mutated MSCs, while absent among ISM female patients with wild-type KIT MSCs. MSCs are multipotent mesodermal progenitor cells present in the BM stroma which diverged from the hematopoietic lineages early during embryogenesis 28 ; thereby, these results would support the notion that in these patients, the KIT mutation could have been acquired in a common pluripotent progenitor cell early during ontogeny, prior to differentiation into MSCs and HPCs.…”

“…Presence of the somatic KIT D816V mutation 1,44 in BM MCs is a molecular hallmark of adult SM 45 and a (minor) diagnostic criterion of the disease. 22,35,36 Additionally, detection of the KIT D816V mutation is thoroughly applied to establish the clonal nature of the disease, 3,22,46 and it has also been used as a molecular marker to track the clonal origin of different hematologic cell lineages within a patient (ie, through the definition of MC-restricted vs multilineage involvement of hematopoiesis) and to establish the clonal relationship between SM MCs and the AHNMD tumor cells in SM-AHNMD.…”

Advances in the understanding and clinical management of mastocytosis and clonal mast cell activation syndromes

“…The current World Health Organization (WHO) classification of the disease includes up to seven distinct categories that meet the diagnostic criteria for mastocytosis ( Table 1). However, the development of new, more sensitive and specific methods, such as multi-parameter flow cytometry and highly sensitive polymerase chain reaction (PCR)-based techniques for the detection of aberrant MCs present at very low frequencies 5– 8 and the study of the KIT mutation in purified cells 9 or blood 10– 12 or both, have led to an unprecedentedly increased rate of detection of phenotypically aberrant and KIT mutated MCs in BM and peripheral blood, pointing out not only the potential need to revise current diagnostic and classification criteria to recognize new entities with very low tumor burden associated with life-threatening symptoms such as anaphylaxis but also a potential impact on the long-term prognosis of patients with indolent forms of the disease.…”