Mutation analysis of C‐KIT in patients with myelodysplastic syndromes without mastocytosis and cases of systemic mastocytosis

Abstract

The proto‐oncogene C‐KIT encodes a tyrosine kinase receptor that is expressed on mast cells and haematopoietic stem cells and can show somatic mutations in patients with mastocytosis. Only scattered information is available about mutations in C‐KIT in patients with other myeloid neoplasms. Moreover, the prevalence of mutations in C‐KIT in bone marrow specimens of individuals with systemic mastocytosis is largely unknown. Using sequence analysis, we have screened cDNAs of the C‐KIT domain encompassing codon 510–626 and codon 763–858 in bone marrow (BM) mononuclear cells (MNCs) of patients with myelodysplastic syndromes (n = 28) and patients with systemic mastocytosis (n = 12) for the presence of mutations. Furthermore, restriction fragment length polymorphism analysis was applied for identification of the C‐KIT 2468A→T and the C‐KIT 1700T→G mutation, as well as the C‐KIT 1642A→C polymorphism. All 11 patients with systemic indolent mastocytosis tested positive for C‐KIT 2468A→T. In contrast, no mutation was identified in the case of aggressive mastocytosis. Among patients with myelodysplastic syndromes, no patient showed a somatic mutation in C‐KIT. The allele frequency for C‐KIT 1642A→C among the entire patient population was 0·038 and was 0·125 among age‐ and sex‐matched healthy controls. Our data demonstrate that myelodysplastic syndromes without histological or cytological evidence of mastocytosis do not exhibit somatic mutations in exons 10, 11, 12, 16, 17 and 18 of C‐KIT. In contrast, BM MNCs of patients with systemic indolent mastocytosis were all positive for C‐KIT 2468A→T and negative for additional mutations in these exons. The C‐KIT 1642A→C polymorphism is not associated with myelodysplastic syndrome or systemic mastocytosis.

Chronic mast cell leukemia (MCL) with KIT S476I: a rare entity defined by leukemic expansion of mature mast cells and absence of organ damage

“…In initial sequencing studies no KIT point mutation at codon 816, the most frequent codon affected in SM [22,23,[27][28][29] could be detected. In a next step, we sequenced all exons of KIT including hot-spot regions where point mutations are expected to occur (exons 5, 9, 10 and 17) [4,29,30].…”

“…In all 6 patients examined, BM and blood cells were tested for the presence of codon 816 mutations according to published methods [18,22,23]. In the patient with chronic MCL, all coding exons of the KIT gene were analyzed by Sanger sequencing.…”

Aberrant expression of CD30 in neoplastic mast cells in high-grade mastocytosis

“…In 36 patients ( 18 In the remaining 39 patients with mastocytosis formalin-fixed and paraffinembedded bone marrow biopsies were analyzed for the c-kit genotype by peptide nucleic acid-mediated PCR clamping and melting point analysis of amplification products as described previously. 37,38 The human mast cell leukemia cell line HMC-1.2, which is known to display the KIT mutation D816V, served as a positive control.…”

“…5,8,[12][13][14] In most patients with systemic mastocytosis, including both those with aggressive systemic mastocytosis/mast cell leukemia and those with indolent systemic mastocytosis, the transforming KIT mutation D816V can be detected. 5,8,[15][16][17][18][19][20] This mutation is associated with autonomous activation of the KIT receptor and is therefore considered to contribute to abnormal growth and survival of neoplastic mast cells in systemic mastocytosis. 21 As KIT D816V is detectable not only in aggressive systemic mastocytosis and mast cell leukemia but also in indolent systemic mastocytosis, 15,19,20 it is thought that additional pro-oncogenic pathways and markers trigger and are indicative of the aggressive disease variants, that is, aggressive systemic mastocytosis and mast cell leukemia.…”

Target interaction profiling of midostaurin and its metabolites in neoplastic mast cells predicts distinct effects on activation and growth

“…In almost all patients, the bone marrow (BM) is affected (1)(2)(3)(4)(5). The transforming KIT mutation D816V is expressed in neoplastic cells in most patients (6)(7)(8)(9)(10).…”