Francismar Prestes Leal

Bio: Francismar Prestes Leal is an academic researcher. The author has contributed to research in topics: Globin & Thalassemia. The author has an hindex of 1, co-authored 1 publications receiving 6 citations.

Prevalence of β(S)-globin gene haplotypes, α-thalassemia (3.7 kb deletion) and redox status in patients with sickle cell anemia in the state of Paraná, Brazil.

Abstract: The aim of this study was to determine the frequency of beta S-globin gene (β(S) globin) haplotypes and alpha thalassemia with 3.7 kb deletion (-α(3.7kb) thalassemia) in the northwest region of Parana state, and to investigate the oxidative and clinical-hematological profile of β(S) globin carriers in this population. Of the 77 samples analyzed, 17 were Hb SS, 30 were Hb AS and 30 were Hb AA. The β(S)globin haplotypes and -α(3.7kb) thalassemia were identified using polymerase chain reaction.Trolox equivalent antioxidant capacity (TEAC) and lipid peroxidation (LPO) were assessed spectophotometrically. Serum melatonin levels were determined using high-performance liquid chromatography coupled to coulometric electrochemical detection. The haplotype frequencies in the SS individuals were as follows: Bantu- 21 (62%), Benin - 11 (32%) and Atypical- 2 (6%). Bantu/Benin was the most frequent genotype. Of the 47 SS and AS individuals assessed, 17% (n = 8) had the -α(3.7kb) mutation. Clinical manifestations, as well as serum melatonin, TEAC and LPO levels did not differ between Bantu/Bantu and Bantu/Benin individuals (p > 0.05). Both genotypes were associated with high LPO and TEAC levels and decreased melatonin concentration. These data suggest that the level of oxidative stress in patients with Bantu/Bantu and Bantu/Benin genotypes may overload the antioxidant capacity.

“Detección de células falciformes mediante la prueba de ciclaje para diagnóstico de anemia drepanocítica en pre-escolares de raza afroecuatoriana de la unidad educativa valle del chota.”

Abstract: La anemia de celulas falciformes es una hemoglobinopatia, producida por una hemoglobina mutante, la hemoglobina S (HbS), es el resultado del reemplazo de la adenina por la timina en el codon del DNA que codifica el acido glutamico, en la posicion 6 de la cadena β de la globina, lo que causa que este aminoacido sea sustituido por valina, este cambio permite que la HbS polimerice facilmente, provocando asi la forma falciforme en el hematie. La presencia de celulas falciformes se establece con base en la identificacion de HbS, mediante distintos metodos siendo la prueba de Ciclaje la aplicada en este estudio, que emplea el metabisulfito de sodio 2%, es un potente agente reductor que desoxigena los hematies con HbS. El enfoque del presente proyecto de investigacion es predominantemente cualitativo aplicando la investigacion de campo, documental y laboratorio, con un nivel de investigacion transversal, descriptivo y de correlacion; tuvo el objetivo de determinar la prevalencia de celulas falciformes en pre-escolares identificados fenotipicamente bajo los rasgos del grupo etnico negroide de la Unidad Educativa Valle del Chota. La muestra estuvo constituida por 64 pacientes, en los cuales, se obtuvo una prevalencia de celulas falciformes en 6 pre-escolares que corresponden al 9,38% con predomino en el sexo masculino en las edades de 4 anos. Al analizar los parametros eritrocitarios, se encontro disminuida la Concentracion de la Hemoglobina Corpuscular Media (CHCM) en la mayoria de los pacientes representando un 79.69%, los demas parametros se encontraron dentro de los valores de referencia.

The frequency of βS-globin haplotypes in the state of Paraná, Brazil, and clinical manifestations of sickle cell anemia

Abstract: Introduction: Haplotypes in the β S-globin cluster are named according to their geographical origin as Central African Republic (CAR), Benin (BEN), Senegal (SEN), Cameroon (CAM) and Arab-Indian. They are considered to have influence on the diversity of clinical manifestations in sickle cell anemia (HbSS). Objective: To identify β S haplotypes and genotypes, their frequencies and their probable association with clinical presentation in patients with sickle cell anemia in the state of Parana. Method: Longitudinal and descriptive study for the definition of haplotypes, and associative study for analysis of their influence on clinical severity. By polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), polymorphic regions of 100 HbSS patients were identified. The association of haplotypes with clinical manifestations was analyzed in a subset of 52 pediatric patients. Results: In the state of Parana, haplotype frequencies were: CAR: 76% BEN: 17.5% SEN: 0.5%, CAM: 0.5% and Atypical (Atp): 5.5%. Genotype frequencies were: CAR/CAR: 62%; CAR/BEN: 20%; CAR/Atp: 6%; CAR/ SEN: 1%; CAR/CAM: 1%; BEN/BEN: 6%; BEN/Atp: 3%, Atp/Atp: 1%. The average percentage of fetal hemoglobin (HbF) in CAR/CAR and CAR/BEN patients was higher than in other studies. Clinical manifestations were not influenced by β S haplotypes. Dactylitis and splenic sequestration occurred more frequently in children below 3 years of age. Conclusion: In this study, no association was found between haplotypes and clinical manifestations, probably given the almost absolute predominance of CAR and BEN haplotypes. However, this fact alerts to the possible influence of other polymorphisms and miscegenation in the Brazilian population.

Sickle cell anemia in the state of Maranhão: a haplotype study.

Abstract: Sickle cell anemia (SCA) is the most severe form of sickle cell disease caused by homozygosity of the βS-gene (S/S or βSβS) and has worldwide distribution. Six polymorphic sites in the β-globin gene cluster were analyzed from a sample of 56 chromosomes of patients with SCA from the state of Maranhao, northeastern Brazil. PCR-RFLP showed that the CAR haplotype was predominant with a frequency of 64.28%, followed by the BEN haplotype (28.57%). Atypical haplotypes were identified at a frequency of 7.15%. Genotypes CAR/CAR, BEN/BEN, and CAR/BEN were present in 46.43%, 10.71%, and 35.71% of patients, respectively. β-Globin haplotype determination is important not only for the monitoring and prognosis of patients with SCA, but it also serves to inform anthropological studies that contribute to elucidating any peculiarities associated with African influences that contributed to the ethnological, economic, cultural, and social formation of Brazil. The high frequency of the CAR/CAR and CAR/BEN haplotypes in this study, which are associated with low levels of fetal hemoglobin, may ultimately reflect a severe clinical course and poor prognosis in patients with SCA in Maranhao.

Alpha thalassemia, but not βS-globin haplotypes, influence sickle cell anemia clinical outcome in a large, single-center Brazilian cohort.

Abstract: Alpha thalassemia and beta-globin haplotype are considered classical genetic disease modifiers in sickle cell anemia (SCA) causing clinical heterogeneity. Nevertheless, their functional impact on SCA disease emergence and progression remains elusive. To better understand the role of alpha thalassemia and beta-globin haplotype in SCA, we performed a retrospective study evaluating the clinical manifestations of 614 patients. The univariate analysis showed that the presence of alpha-thalassemia -3.7-kb mutation (αα/-α and -α/-α) decreased the risk of stroke development (p = 0.046), priapism (p = 0.033), and cholelithiasis (p = 0.021). Furthermore, the cumulative incidence of stroke (p = 0.023) and cholelithiasis (p = 0.006) was also significantly lower for patients carrying the alpha thalassemia -3.7-kb mutation. No clinical effects were associated with the beta-globin haplotype analysis, which could be explained by the relatively homogeneous haplotype composition in our cohort. Our results reinforce that alpha thalassemia can provide protective functions against hemolysis-related symptoms in SCA. Although, several genetic modifiers can impact the inflammatory state of SCA patients, the alpha thalassemia mutation remains one of the most recurrent genetic aberration and should therefore always be considered first.