ABSTRACT
Objective To evaluate the clinical significance of bone marrow minimal residual disease (MRD) monitoring by multi-parameter flow cytometry (FCM) regularly after the first complete remission (CR1) in patients with acute myeloid leukemia (AML).Methods A total of 63 paitents with AML who had got CR1 after chemotherapy were regularly monitored for MRD in bone marrow by FCM,and MRD ≥ 10-4 was positive.According to the latest standards of National Comprehensive Cancer Network (NCCN) for disease risks,they were categorized into three groups:better risk group (20 cases),intermediate risk group (27 cases) and poor risk group (16 cases).The probability of continuous complete remission (CCR) was calculated by KaplanMeier formula,and the statistical difference between MRD positivc and MRD negative CCR probabilities was evaluated by log-rank test.Results The positive rates of MRD were 20％(4/20),30％(8/27) and 10/16 in better risk group,intermediate risk group and poor risk group respectively.The difference between better risk group and intermediate risk group had no statistical significance (P=0.454),and the difference between poor risk group and intermediate risk group had statistical significance (P =0.035).Twenty-two cases showed positive MRD,and 41 cases showed negative MRD.The probability of CCR at 24 and 36 months in MRD positive patients were 18％ (4/22),18％ (4/22),in MRD negative patients were 83％ (34/41),80％ (33/41),and there were significant differences (P ＜ 0.01).Conclusions The dynamic detection of MRD by FCM can be used to evaluate the therapeutic effect and prognosis of AML.MRD monitoring has important clinical significance and can help to adjust the intensity of chemotherapy,carry out individualized treatment,predict prognosis,and choose appropriate therapy.
ABSTRACT
<p><b>OBJECTIVE</b>To assess the practicality of rapid prenatal screening for Down syndrome (DS) by polymerase chain reaction-short tandem repeat (PCR-STR) method, and to determine the genotypes of 7 STR loci in ethnic Chinese Han from Weifang region.</p><p><b>METHODS</b>Seven STR markers (D21S11, D21S1411, D21S1412, D21S1413, D21S1414, D21S1432 and D21S2039) from chromosome 21q22.1-22.2 region were selected. Amniotic samples from 978 high-risk pregnancies and peripheral blood samples from 82 patients suspected with DS were tested with PCR-STR. And the results were verified with G-banding analysis.</p><p><b>RESULTS</b>(1) All of the 1060 samples were successfully tested by PCR-STR. For normal individuals, the patterns obtained by PCR-STR were two bands with 1:1 area ratio or a single band. For DS cases, by contrast, the patterns revealed either three bands with area ratio of 1:1:1 for two STR loci, or three bands with area ratio of 1:1:1 for one STR loci and two bands with 2:1 or 1:2 area ratio for two STR loci. Based on analysis of the 7 STR markers, 14 amniotic fluid samples and 26 peripheral blood samples were regarded as DS positive. (2) For the 978 amniotic fluid samples, cytogenetic analysis was successful in 961 (98.3%), among which 44 had an abnormal karyotype. These included 14 trisomy 21 (12 standard type, 1 mosaicism and 1 translocation). 17 cases which failed amniocytic culture were normal upon fetal blood karyotyping. (3) Cytogenetic analysis was successful in all of the 82 peripheral blood samples, and has identified 30 (36.6%) abnormal karyotypes, among which 26 were trisomy 21 (including 4 with translocation form). (4) For DS positive cases, STR 1-4 showed three bands with area ratio of 1:1:1, or there were 2-4 loci with two bands with an area ratio of 2:1 or 1:2. All of the DS cases detected by PCR-STR were confirmed by karyotyping. (5) All of the 7 selected loci were informative, with their degrees of heterozygosity ranging between 0.624 and 0.812. D21S2039 and D21S1412 had the highest heterozygosities (> 0.80), D21S1411 and D21S1432 had the lowest (< 0.70). D21S11 and D21S2039 showed the highest rate (≥ 40%) of three bands with area ratio 1:1:1. However, D21S1411, D21S1432 and D21S1413 markers had the highest rate of homozygosity (≥ 30%).</p><p><b>CONCLUSION</b>PCR-STR assay may provide an effective alternative for rapid prenatal DS screening. The 7 selected STR markers are highly informative. The result has featured good accuracy and reliability.</p>