Internal tandem duplication of the FLT3 gene and clinical evaluation in childhood acute myeloid leukemia. The Children's Cancer and Leukemia Study Group, Japan.

We analyzed tandem duplication in the juxtamembrane (JM) domain of the FLT3 (FMS-like tyrosine kinase 3/FLK2, CD135) gene in 94 children with acute myeloid leukemia (AML) and evaluated its correlation with clinical features. Longer polymerase chain reaction (PCR) products were observed in five patients; 1/3 of M0, 119 of M1, 1/39 of M2, 1/9 of M3 and 1/12 of M5. The sequence analyses of abnormal PCR products showed that all the abnormal products were derived from tandem duplications involving the JM domain and that all the lengthened sequences were in-frame as we previously reported. Statistical analyses revealed a significantly lower incidence of the tandem duplication in childhood AML patients than in adult patients (P < 0.05), and significantly shorter disease-free survival in patients with mutant FLT3 than in patients with wild-type FLT3 (P < 0.05). Our results suggest that the tandem duplication in the JM domain of the FLT3 gene is not a frequent phenomenon but might be a factor of poor prognosis in childhood patients with AML.

Prognostic impact of CD45 antigen expression in high-risk, childhood B-cell precursor acute lymphoblastic leukemia.

To evaluate the clinical implications of CD45 expression in acute childhood lymphoblastic leukemia (ALL), we measured the CD45 expression of blast cells from 133 untreated patients with childhood B-precursor ALL (n = 118) or T-ALL (n = 15). CD45 expression (> or = 20%) was detected in all 15 cases (100%) of T-ALL, and 101 cases (86%) of B-precursor ALL. In 122 cases, the fluorescence intensity of the CD45 expression was measured as a relative value; the ratio of average linear values (RALV) of CD45 on the blasts to that on CD3-positive T-lymphocytes from the same specimen. The expression was more intense in the T-ALL cases than in the B-precursor ALL cases (RALV, mean +/- SE: T-ALL 0.230 +/- 0.04 vs. pro-B ALL 0.150 +/- 0.012/pre-B ALL 0.153 +/- 0.019, p < 0.05). However, the intensity of the CD10, CD19, CD20 and CD34 antigen immunoreactivity did not correlate with the CD45 expression. Patients with hyperdiploidy (chromosome number > 50) showed significantly lower levels of CD45 expression than patients with t(1;19) or normal karyotypes (RALV, mean +/- SE: 0.081 +/- 0.022 vs. 0.133 +/- 0.03/0.143 +/- 0.019, p < 0.05). Other clinical features such as age, gender and WBC count did not correlate with CD45 expression. The prognostic implications of CD45 expression were studied in non-high-risk (low-risk + intermediate-risk) (n = 60) and high-risk patients (n = 52) with B-precursor ALL who had been treated with the risk-directed protocol of ALL-941 trial. Although CD45 expression did not correlate with the event-free survival (EFS) of the non-high-risk patients, there was a significant correlation between the expression levels and the EFS of the high-risk patients: the 3-year EFS rate of the CD45low group (n = 26, RALV = 0.017-0.132) was 88 +/- 7% versus the CD45high group (n = 26, RALV = 0.133-0.450) at 34 +/- 24% (p < 0.05). These results show that the levels of expression of the CD45 antigen on leukemic lymphoblasts are significantly correlated with the clinical features and prognosis of childhood ALL.

A case of pseudo-Zellweger syndrome with a possible bifunctional enzyme deficiency but detectable enzyme protein. Comparison of two cases of Zellweger syndrome.

Three infants with peroxisomal disorders were investigated clinicobiochemically and neuroradiologically. Two had classical Zellweger syndrome, and cranial CT scans showed typical disproportionate enlargement of the occipital horns of the lateral ventricles (colpocephaly) with marked hypodensity of the white matter. In one female infant, although the clinical findings were similar to those in Zellweger syndrome, some findings, such as elevated transaminase levels, liver fibrosis, the absence of renal cortical cysts and colpocephaly, were negative or milder. Biochemical analyses revealed increased very long-chain fatty acids, dicarboxylic aciduria and impaired beta-oxidation of lignoceric acid. However, peroxisomes were abundantly present in hepatocytes and cultured fibroblasts, and all peroxisomal beta-oxidation enzyme proteins were detected on immunoblot analysis. A cell fusion study suggested that the enzyme responsible for this case of 'pseudo-Zellweger syndrome' is bifunctional.

[Clonal analysis by fluorescence in situ hybridization in a patient with de nove acute myeloid leukemia with myelodysplasia].

A 12-year-old girl presenting leukocytosis, anemia and thrombocytopenia was diagnosed as de nove acute myeloid leukemia (AML, M2) with concurrent myelodysplastic features in myeloid and erythroid cells. Her karyotype was defined as 47, XX, +8[20]. Though she was treated successfully with multi-drug chemotherapy, she relapsed after 2 years of remission. A bone marrow transplantation from HLA matched her brother was performed to induce hematological remission which persisted for one year. She again relapsed with AML with myelodysplasia, and an abnormal complex karyotype was newly detected. She eventually died without further chemotherapy. We performed FISH on the patient's stained bone marrow smears using DNA probes for chromosome 8 and Y to analyze the clonality. The results showed that the most of blasts and bone marrow cells except lymphoid cells were of trisomy 8 at onset, while in the 1st remission, trisomy 8 clone was slightly detected only in monocytes. At 1st and 2nd relapse, trisomy 8 clone was detected again in most of myeloid cells. Thus, in this case, it was considered that underlying stem cell disorder with trisomy 8 during the entire disease course contributed to leukemogenesis.

[Prognostic significance of chromosome analysis in childhood acute lymphoblastic leukemia. Children's Cancer and Leukemia Study Group (CCLSG)].

We analyzed the prognostic significance of chromosomal findings in children with acute lymphoblastic leukemia (ALL), treated according to the Children's Cancer and Leukemia Study Group protocols between 1987 and 1993. Patients were classified into 5 groups according to chromosome number. The patients with a hyperdiploid(> 50) karyotype(13%) had the best prognosis [4-year event-free survival (EFS): 83 +/- 6%], while those with a pseudodiploid karyotype (24%) had the worst prognosis(4-year EFS: 52 +/- 6%) (log-rank, p = 0.03). However, multivariate analysis revealed that the ploidy classification had no prognostic significance in terms of EFS. When patients were classified according to chromosome abnormalities, those with any type of translocation had a worse outcome (4-year EFS: 33 +/- 9%) than those with hyperdiploidy(> 50), normal diploidy, and other abnormalities(log-rank, p < 0.0001). Multivariate analysis revealed that chromosome abnormalities were an independent prognostic factor (relative risk 3.98; p < 0.0001). Patients with t(1; 19) had an EFS similar to that of patients with chromosome abnormalities other than translocations or normal diploidy. We conclude that chromosomal findings have prognostic significance, although some chromosome abnormalities lost their statistical significance after modern intensified chemotherapy. Childhood ALL should be further stratified according to chromosome classification.

[Treatment results of intermittent and cyclic regimen with ATRA and chemotherapy in childhood acute promyelocytic leukemia. Children's Cancer and Leukemia Study Group].

An intermittent and cyclic regimen with All-Trans Retinoic Acid (ATRA) and intensive chemotherapy was conducted due to pharmacokinetic studies on ATRA for acute promyelocytic leukemia (APL) in children. We have treated 17 children with APL using ATRA for remission induction followed by an intermittent schedule of ATRA plus intensive chemotherapy (APL-ATRA protocol). There were 10 males and 7 females. The median age was 9.0 years old. The median baseline white blood cell count was 12.1 x 10(3)/microliter, hemoglobin 7.8 g/dl, platelet 4.5 x 10(4) microliters at diagnosis. Sixteen patients showed t(15; 17) translocation. RT-PCR analysis was available in 15 patients and showed PML/RAR alpha rearrangement in all patients. Overall, 13 or 17 newly diagnosed patients (88%) achieved complete remission and EFS was 67%. Compared to the control (same chemotherapy without ATRA regimen), remission induction and EFS were significantly increased. The toxicity of ATRA consisted of retinoic acid syndrome in 1 and pseudotumor cerebli in another. Other toxicities included headache, chelitis, gastrointestinal trouble and bone pain. These results suggest that intermittent and cyclic regimen with ATRA and intensive chemotherapy (APL-ATRA protocol) is highly effective for APL patients.

Retrospective analysis of clonality and detection of residual disease in myeloid leukemia by FISH on long-term stored bone marrow smears.

BACKGROUND: Fluorescence in situ hybridization (FISH) has allowed the detection of numerical chromosomal aberrations in interphase nuclei on fresh or frozen smears of leukemia. METHODS: To analyze clonality and residual disease in myeloid leukemia retrospectively, we applied FISH to bone marrow smears stored at ambient temperature for up to 9 years. RESULTS: When hybridization efficiency was investigated on stored control smears from patients without hematological malignancy, more than 96% of nuclei showed the expected number of signals using DNA probes specific for chromosome 7, X or Y. In combination with cell morphology, we observed much higher hybridization efficiency in blasts and granulomonocytic cells compared with lymphoid and erythroid cells. On the basis of good hybridization efficiency for old smear specimens, we applied FISH to stored bone marrow smears of myeloid leukemias, in which either loss of chromosome 7 or loss of sex chromosomes had been verified previously by conventional cytogenetics (one patient with chronic myelomonocytic leukemia (CMML) and four with acute myeloid leukemia (AML; three M2 and one M7)). As a result, the loss of chromosome was detected in blasts from all patients and was observed in mature granulocytes, except in M7. In the CMML patient and one AML (M2) patient with t(8;21), lymphoid and erythroid cells also showed the loss of chromosomes, suggesting that it should occur at stem-cell level. A high amount of residual disease was detected in the morphological remission samples in one AML (M2) patient after induction therapy. The patient eventually succumbed to relapse. CONCLUSION: Thus, the present FISH technique is useful to analyze the clinical significance of clonality and the residual disease in myeloid leukemia, retrospectively.

Zellweger syndrome and a microdeletion of the proximal long arm of chromosome 7.

A 16-day-old girl with Zellweger syndrome and a chromosomal rearrangement, 46,XX,del(7)(q11.22q11.23), is reported. The diagnosis was confirmed by marked deficiencies of peroxisomal beta-oxidation enzymes and dihydroxyacetone phosphate acyltransferase activities in rectal cells and fibroblasts obtained by biopsy and in hepatic cells obtained at autopsy. This is the first report of Zellweger syndrome associated with a chromosomal arrangement, a microdeletion of chromosome 7. A tentative gene assignment to 7q11 is suggested.