[Clinical and laboratory characteristics of two acute lymphoblastic leukemia patients with dicentric (9; 20) (p11 - 13; q11)].

OBJECTIVE: To explore the morphologic, immunophenotypic, cytogenetic and clinical features of acute lymphoblastic leukemia (ALL) patients with dicentric (9; 20) (p11 - 13; q11). METHODS: Chromosome specimens of bone marrow cells were prepared by direct method and/or short-time culture. Karyo-typing was performed by R-banding technique. Dual-color fluorescence in situ hybridization (FISH) was performed using both chromosome 9 classical satellite probe and chromosome 20 alpha-satellite probe in one patient. RESULTS: The two ALL patients were positive for CD10 and HLA-DR, showing of B cell origin. Both patients had dicentric (9; 20): case 1 was 45, XY, der (9) t (9; 20) (p11; q11), -20[20]; case 2 was 45, XX, der (9) t (9; 20) (p13; q11), t (9; 22) (q34; q11), -20[10]/46, idem, +8[16]/47, idem, +8, +21[14]. Mutual translocation between chromosomes 9 and 20 of the dicentric chromosome was confirmed by FISH in one patient. CONCLUSIONS: Dicentric (9; 20) (p11 - 13; q11) is a rare recurring chromosome abnormality associated with ALL. Because of the subtle nature of the translocation, FISH is essential for the detection of this abnormality.

[Clinical and experimental study of two cases of myelodysplastic syndromes with double isochromosome 20q- anomaly].

OBJECTIVE: To explore the clinical and laboratory characteristics of two myelodysplastic syndromes (MDS) patients with double isochromosome 20q- anomaly. METHODS: Bone marrow cell chromosome preparations were made with both direct method and short-term culture. Karyotype analysis was performed by R-banding technique, and dual-color FISH (fluorescence in situ hybridization) by using a 20q telomeric probe and a sequence-specific probe for 20q12. RESULTS: The clinical and hematological findings were comparable with diagnosis of MDS. Karyotype analysis showed that both patients had double isochromosome 20q- anomaly: case 1 is 46, XX, der(20)? i(20q-) [6]/46, idem, der (6) i (6p) [1]/47, idem, +der (20)? i (20q-) [3]/47, idem, der(6)i (6p), +der(20)? i (20q-) [20]; case 2 is 45, XY, -7, der (20)? i (20q-) [17]/46, idem, +der(20) ? i(20q-) [3]. Two derivative chromosomes 20 were proved 20q isochromosomes with interstitial deletions by dual-color FISH in one patient. CONCLUSIONS: Double isochromosome 20q- anomaly is a rare recurrent karyotype abnormality in MDS, and signals a poor prognosis.

[Relationship of plasma homocysteine and folic acid levels and 5,10-methylenetetrahydrofolate reductase gene mutation with venous thromboembolism].

OBJECTIVE: To investigate the association between concentrations of plasma homocysteine and folic acid, 5,10-methylenetetrahydrofolate reductase (MTHFR) C667T mutation and venous thromboembolism (VTE) and to analyze the effect of MTHFR C667T mutation on concentrations of plasma homocysteine and folic acid. METHODS: In 58 patients with VTE and 58 sex and age matched controls, epidemiological risk factors were surveyed. The concentration of plasma homocysteine was measured by high performance liquid chromatography, and the concentration of plasma folic acid was measured by radioimmunoassay. MTHFR C667T genotype was measured by PCR-RFLP. RESULTS: The concentrations of plasma homocysteine and folic acid showed significant difference between the case group and the control group (OR = 1.5, 95% CI: 1.216 - 2.213 and OR = 0.396, 95% CI: 0.149 - 0.709, respectively). There was no significant difference in the frequency of mutant alleles in site 667 of MTHFR gene between the cases and the controls (P > 0.05). The concentration of plasma folic acid was associated with the concentration of plasma homocysteine (multiple correlation coefficient = -2.061, P < 0.05). The MTHFR C667T polymorphism was associated with the concentration of plasma folic acid but not with the concentration of plasma homocysteine in both the case group and the control group. The multiple correlation coefficient between the MTHFR C667T polymorphism and the concentration of plasma folic acid is 0.5856 (P < 0.01). CONCLUSIONS: The results of our study demonstrate that hyperhomocysteinemia and folic acid deficiency are independent risk factors for VTE. Folic acid deficiency is a cause of hyperhomocystinemia while the MTHFR C667T mutation is one of the possible genetic factors causing folic acid deficiency in this Chinese population.

[Microsequencing, analysis of molecular weight and amino acid composition for pyrimidine 5'-nucleotidase I of human erythrocytes].

To further explore the mechanism of congenital pyrimidine 5'-nuleotidase I (P5'N-I) deficiency, on the basis of purification of the protein, the molecular weight and amino acid composition were analysed by mass-spectrograph and amino-acid analyzer, microsequencing and bioinformation analysis of P5'N-I were performed after it was hydrolysed by trypsin. The results showed that three fractions were found in the purified P5'N-I and their molecular weights were 26,952.9, 55,476 and 110,938, respectively. The sequence from one of the peptide fragments was I-E-G-P-T-I-R-Q-I-E. The homologous sequence was not found after comparision with the ten-amino-acid sequence in GenBank by blast procedure. Amino acid analysis indicated that P5'N-I was composed of 18 amino acids at least, and 243 amino acid residues. In conclusion, the enzyme might be an allosteric enzyme, there might be homologous dimer or tetramer in physiological status of normal human erythrocyte, the microsequence could be designed as the probe for fishing the genes of interest. The composition of amino acid might be an important information in determination of its protein primary structure.