Exposure to benzene has been associated with haematological diseases such as neutropenia (NEB) and acute myeloid leukaemia (AML). We tested whether the null genotypes of the GSTM1 and GSTT1 genes, involved in benzene inactivation, altered the risk for NEB in southeastern Brazil. Genomic DNA from 55 NEB patients and 330 controls was analysed by multiplex-polymerase chain reaction. The frequency of the GSTM1, GSTT1 and combined null genotypes was similar in patients and controls (GSTM1, 27.3% vs. 38.8%, p = 0.16; GSTT1, 25.5% vs. 19.7%, p = 0.24; GSTM1/GSTT1, 12.7% vs. 6.7%, p = 0.26; respectively). The distribution of genotype classes in NEB patients was similar to normal controls, suggesting that GSTM1 and GSTT1 null genotypes make no specific contribution to the risk of NEB. As the GSTM1 and GSTT1 null genotypes were previously associated with increased risk for AML in Brazil and elsewhere, we hypothesise that different thresholds of chemical exposure relative to distinct GSTM1 and GSTT1 genotypes may determine whether AML or NEB manifests in benzene exposed individuals from southeastern Brazil. Although indicative, our results still require support by prospective and large scale epidemiological studies, with rigorous assessment of daily chemical exposures and control of the possible contribution of other polymorphic genes involved in benzene metabolism.

A função discriminante baseada na distribuição do tamanho dos eritrócitos (RDW) e outra função discriminante incorporando o RDW (MCV² x RDW/Hgb x 100) foram determinadas em um grupo de 30 pacientes com anemia ferropriva, 30 pacientes com beta talassemia menor e 30 indivíduos normais. Os valores médios do RDW e do (MCV² x RDW/ Hgb x 100) foram significativamente maiores em pacientes com anemia ferropriva quando comparados aos obtidos em pacientes com beta talassemia menor (p<0.001). Considerando os valores de RDW iguais ou superiores a 21.0% entre os pacientes com anemia microcítica, nós identificamos corretamente 90% dos pacientes com anemia ferropriva, sendo que a sensibilidade e a especificidade do teste foram 90.0% (IC 95%: 0.75 - 0.96) e 77.0% (IC 95%: 0.60 - 0.88), respectivamente. Valores de RDW menores do que 21.0% identificaram corretamente 77.0% dos pacientes com beta talassemia menor, com sensibilidade e especificidade de 77.0% (IC 95%: 0.60 - 0.88) e 90.0% (IC 95%: 0.75 - 0.96), respectivamente. Considerando valores de (MCV² x RDW/Hgb x 100) maiores e menores do que 80.0% como indicativos de anemia ferropriva e beta talassemia menor, respectivamente, nós identificamos corretamente 97.0% dos pacientes de cada grupo, com sensibilidade e especificidade de 97.0 (IC 95%: 0.84 - 0.99). Estes resultados indicaram que a função discriminante (MCV² x RDW/Hgb x 100) é um método altamente sensível e específico para a triagem inicial de pacientes com anemia microcítica e é superior ao RDW para a diferenciação de pacientes com anemia ferropriva daqueles com beta talassemia menor.

The red cell distribution width (RDW), and another red cell discriminant function incorporating RDW (MCV² x RDW/Hgb x 100) were determined in a group of 30 patients with iron deficiency anemia, 30 patients with beta thalassemia trait, and 30 normal subjects. Both RDW and (MCV² x RDW/Hgb x 100) mean values were significantly higher in iron deficiency anemia than in beta thalassemia trait (p<0.001). Taking RDW equal or above 21.0 percent among microcytic anemia patients, we identified correctly 90.0 percent of patients with iron deficiency anemia. The sensitivity and specificity of the test were 90.0 percent (IC 95 percent: 0.75 - 0.96) and 77.0 percent (IC 95 percent: 0.60 - 0.88), respectively. RDW values below 21.0 percent identified correctly 77.0 percent of beta thalassemia trait with a sensitivity and a specificity of 77.0 percent (IC 95 percent: 0.60 - 0.88) and 90.0 percent (IC 95 percent: 0.75 - 0.96), respectively. Taking values of (MCV² x RDW/Hgb x 100) above and below 80.0 percent as indicative of iron deficiency and beta thalassemia trait, respectively, we identified correctly 97.0 percent of those patients in each group. Both sensitivity and specificity were 97.0 percent (IC 95 percent: 0.84 - 0.99). These results indicated that the red cell discriminant function incorporating volume dispersion (MCV² x RDW/Hgb x 100) is a highly sensitive and specific method in the initial screening of patients with microcytic anemia and is better than RDW in differentiating iron deficiency anemia from beta thalassemia trait.