Analysis of ITD characteristics in acute myeloid leukemia patients with FLT3-ITD positive / 中国实验血液学杂志

The aim of this study was to analyze the FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) allelic ratios (AR), number of ITD, ITD length and positions of ITD insertions in de novo acute myeloid leukemia (AML) patients with FLT3-ITD positive, and the relationship between mutant level and therapeutic efficacy. Genomic DNA was amplified by PCR, capillary electrophoresis was used to detect the ITD characteristics in 31 de novo AML patients, and DNA sequences analysis of FLT3-ITD(+) were performed in 13 patients. The results showed that the ratios of mutant to wild type FLT3 allele ranged from 0.01 to 2.8; 28 patients (90.32%) had a single ITD, the remaining 3 patients had more than one ITD; the ITD length ranged from 3 to 144 bp in all FLT3-ITD(+) patients. 13 sequence-analyzed patients, 4 patients were of pure duplications, and 2 patients had foreign bases inserted, and the other 7 patients were partial duplications. The ITD occurred in the regions from p.E573 to p.P606 of the FLT3 protein, with the majority clustered in a stretch between p.F590 and p.R595. The complete remission (CR) rate in AR < 0.5 patients (43.75%) were more prevalent as compared with AR ≥ 0.5 patients (16.67%) (p > 0.05). It is concluded that the ITD length and AR are vary widely. Some of the insertions are foreign bases, and all of the 13 sequences-analyzed ITD were concentrated on the juxtamembrane domain. The CR rate in patients of AR < 0.5 had no statistical significance compared with patients of AR ≥ 0.5.

Two novel EIF2AK3 mutations in a Chinese boy with Wolcott-Rallison syndrome / 中华儿科杂志

<p><b>OBJECTIVE</b>Wolcott-Rallison syndrome (WRS) is a rare autosomal recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes, multiple epiphyseal dysplasia and growth retardation, and other variable multisystem clinical manifestations. Here we describe a Chinese boy affected by WRS. Genetic testing of his EIF2AK3 gene was performed in order to elucidate molecular variations and subsequently to provide credible genetic counseling for prenatal diagnosis in his family.</p><p><b>METHOD</b>Based on analysis of a nine-year-old boy's clinical symptoms associated with biochemical examination and imaging, the diagnosis of WRS was therefore made. Genomic DNAs were extracted from peripheral blood leukocytes from the boy and his parents with their informed consent for genetic studies. All EIF2AK3 exons and intron-exon boundaries were amplified by Touch-down polymerase chain reaction (Touch-down PCR) and sequenced.</p><p><b>RESULT</b>Direct sequencing of PCR products revealed the presence of a heterozygous T insertion (c.1408_1409insT) in exon 8 of the EIF2AK3 gene leading to frameshifting and termination, and another heterozygous T to A exchange (c.1596T > A) in exon 9 of the EIF2AK3 gene resulting in nonsense C532X mutation.</p><p><b>CONCLUSION</b>Combining mutation screening of EIF2AK3 gene with clinical manifestations and effective examination may provide a reliable diagnostic method for patients. In this research, two novel mutations identified in the Chinese boy locate in the catalytic domain of the EIF2AK3 gene, disrupting the ability of autophosphorylation, leading to the truncated proteins that are unable to phosphorylate the natural substrate, which are responsible for the phenotype of Wolcott-Rallison syndrome.</p>

FMS-like tyrosine kinase 3 gene mutation in acute myeloid leukemia detected by denaturing PAGE and its clinical significance / 中国实验血液学杂志

The aim of this study was to analyze the frequency of flt3 length mutation (flt3-LM) in de novo acute myeloid leukemia patients and the relationship between flt3-LM and chromosome alterations, FAB subgroups, as well as efficiency of therapy. Genomic DNA was amplified by PCR; 2% agarose gel or 8% denaturing PAGE were used to detect the length mutation of flt3 gene in 99 de novo acute myeloid leukemia patients; karyotyping in 72 AML patients was performed by G banding technique. The results showed that the flt3-LM was detected in 20.2% (20/99) patients by agarose gel electrophoresis, and in 29.9% (29/99) by denaturing PAGE. The flt3-LM was not detected in M(0) (only one patient was available), but flt3-LM occurrence in AML subtypes was as follow: in M(2) (9/30), M(3) (6/27), M(4) (4/14), M(5) (7/19), M(6) (3/8) respectively. flt3-LM in patients with normal karyotypes (39.13%) was more prevalent as compared with patients of abnormal karyotype (24.49%), but there was no statistical difference (p > 0.05). The complete remission (CR) rate in flt3-LM positive patients (36.36%) was lower than that in flt3-LM negative patients (62.75%) in the 73 patients (p < 0.05) whose karyotypic detection was performed. The distributions of flt3-LM were observed in 8 out of 40 CR patients, 8 out of 21 PR patients, and 6 out of 12 NR patients. It is concluded that the denaturing PAGE is more sensitive and reliable to detect the flt3-LM. The flt3 mutation represents a common genetic abnormality in AML patients, and the flt3-LM is associated with lower CR rate.