A recurrent in-frame insertion in a CEBPA transactivation domain is a polymorphism rather than a mutation that does not affect gene expression profiling–based clustering of AML

Abstract

The transfusion of random platelets did result in a rise in platelet count (mean increments: 68 ϫ 10 9 /L and 87 ϫ 10 9 /L at day 0 and day 1, respectively), but this was significantly and consistently less over the lifespan of the transfused platelets than the mean increment seen with AC-Tx (116 ϫ 10 9 /L and 146 ϫ 10 9 /L on days 0 and 1, respectively). More importantly, the survival of the random platelets was only approximately half that of antigen-compatible platelets (T 1/2 of random platelets, 1.0 days; antigen-compatible platelets, 1.9 days) ( Figure 1).The range of day-1 increments varied widely, both with R-Tx (range: 10-217 ϫ 10 9 /L) and AC-Tx (range: 62-216 ϫ 10 9 /L). Unexpectedly large increments may occur with R-Tx when a proportion of the platelets is coincidentally HPA-1a/5b negative (estimated likelihood, 1 in 13 where the platelet pool is from 4 "random" donors) 2 ; unexpectedly low increments may be seen with AC-Tx due to the presence in the fetal circulation of maternal HLA class I antibodies 3 or when platelet transfusions are inappropriately administered. Babies with NAIT should therefore have their platelet counts monitored regularly whatever treatment is used and appropriate changes to treatment instigated when necessary.In conclusion, we agree with Kiefel et al that R-Tx is an acceptable initial treatment for NAIT where HPA-1a/5b-negative platelets are not immediately available. However, our data show that HPA-1a/5b-negative platelets give larger increments, have a longer half-life, and only occasionally fail to provide therapeutically significant platelet increments. We therefore encourage blood services in other countries to establish panels of HPA-1a/5b-negative donors to provide HPA-1a/5b-negative platelets for immediate use in cases of suspected NAIT and for intrauterine or neonatal therapy of cases of known NAIT. 4

A Comparison of Two Methods for Screening CEBPA Mutations in Patients with Acute Myeloid Leukemia

“…Although this particular insertion was a polymorphism, it is possible that a true mutation could be missed by a sequencing method alone due to low detection limit. 9,11,12 Taken together, our results suggest that the optimal approach for detecting CEBPA mutations in AML may be a combination of direct sequencing and a modified version of the fragment length analysis assay. Direct se-quencing is absolutely necessary to detect substitution mutations, but concurrent fragment length analysis offers greater sensitivity for detecting insertion or deletion mutations.…”

“…Samples from two patients had a TAD2 (1175 to 1180dup: ϩ6 bp) insertion previously reported as a polymorphism. 9,12,13 One polymorphism (patient G2) was initially detected only by fragment analysis. That case was classified as wild-type without a polymorphism by initial sequencing analysis, but the polymorphism was confirmed after sequencing more colonies.…”

Characterization of CEBPA Mutations and Polymorphisms and their Prognostic Relevance in De Novo Acute Myeloid Leukemia Patients

“…The c.584-589dup ACCCGC leading to p.P194_H195dup (proline-histidine duplication) was initially reported as mutation but later found as a germline polymorphism (Frohling et al, 2004;Lin et al, 2005;Resende et al, 2007;Wouters et al, 2007). This polymorphism was reported in 3.1-39% in normal healthy controls (Pabst et al, 2001;Lin et al, 2005;Resende et al, 2007) and 3.2-20% in AML (Lin LI et al, 2005;Resende C et al, 2007;Leecharendkeat et al, 2008).…”

CCAAT/enhancer binding protein‐alpha polymorphisms occur more frequently than mutations in acute myeloid leukemia and exist across all cytogenetic risk groups and leukemia subtypes

“…12,16,19,20 In one study, the nt1175_1180dup was initially reported as a pathogenic mutation although later found to be a polymorphism as this alteration was present in the germ line and corresponds to the nonpathogenic polymorphism. 16,27 Some recent studies also detected this polymorphism in normal individuals and remission samples. 16 As the frequency of polymorphisms in this study was quite high and the numbers of cases with polymorphisms were enough to assess the clinical association, we decided to evaluate the clinical relevance of these polymorphisms.…”