RESUMEN
The fetal hemoglobin (HbF) levels and betaS-globin gene haplotypes of 125 sickle cell anemia patients from Brazil were investigated. We sequenced the Gg- and Ag-globin gene promoters and the DNase I-2 hypersensitive sites in the locus control regions (HS2-LCR) of patients with HbF level disparities as compared to their ßS haplotypes. Sixty-four (51.2 percent) patients had CAR/Ben genotype; 36 (28.8 percent) Ben/Ben; 18 (14.4 percent) CAR/CAR; 2 (1.6 percent) CAR/Atypical; 2 (1.6 percent) Ben/Cam; 1 (0.8 percent) CAR/Cam; 1 (0.8 percent) CAR/Arab-Indian, and 1 (0.8 percent) Sen/Atypical. The HS2-LCR sequence analyses demonstrated a c.-10.677G>A change in patients with the Ben haplotype and high HbF levels. The Gg gene promoter sequence analyses showed a c.-157T>C substitution shared by all patients, and a c.-222_-225del related to the Cam haplotype. These results identify new polymorphisms in the HS2-LCR and Gg-globin gene promoter. Further studies are required to determine the correlation between HbF synthesis and the clinical profile of sickle cell anemia patients.
Asunto(s)
Adulto , Niño , Preescolar , Humanos , Persona de Mediana Edad , Anemia de Células Falciformes/genética , Desoxirribonucleasa I/genética , Globinas/genética , Región de Control de Posición/genética , Hemoglobina Fetal/análisis , Genotipo , Marcadores Genéticos/genética , Haplotipos , Regiones Promotoras GenéticasRESUMEN
ßS-Globin haplotypes were studied in 80 (160 ßS chromosomes) sickle cell disease patients from Salvador, Brazil, a city with a large population of African origin resulting from the slave trade from Western Africa, mainly from the Bay of Benin. Hematological and hemoglobin analyses were carried out by standard methods. The ßS-haplotypes were determined by PCR and dot-blot techniques. A total of 77 (48.1 percent) chromosomes were characterized as Central African Republic (CAR) haplotype, 73 (45.6 percent) as Benin (BEN), 1 (0.63 percent) as Senegal (SEN), and 9 (5.63 percent) as atypical (Atp). Genotype was CAR/CAR in 17 (21.3 percent) patients, BEN/BEN in 17 (21.3 percent), CAR/BEN in 37 (46.3 percent), BEN/SEN in 1 (1.25 percent), BEN/Atp in 1 (1.25 percent), CAR/Atp in 6 (7.5 percent), and Atp/Atp in 1 (1.25 percent). Hemoglobin concentrations and hematocrit values did not differ among genotype groups but were significantly higher in 25 patients presenting percent fetal hemoglobin ( percentHbF) > or = 10 percent (P = 0.002 and 0.003, respectively). The median HbF concentration was 7.54 ± 4.342 percent for the CAR/CAR genotype, 9.88 ± 3.558 percent for the BEN/BEN genotype, 8.146 ± 4.631 percent for the CAR/BEN genotype, and 4.180 ± 2.250 percent for the CAR/Atp genotype (P = 0.02), although 1 CAR/CAR individual presented an HbF concentration as high as 15 percent. In view of the ethnic and geographical origin of this population, we did not expect a Hardy-Weinberg equilibrium for CAR/CAR and BEN/BEN homozygous haplotypes and a high proportion of heterozygous CAR/BEN haplotypes since the State of Bahia historically received more slaves from Western Africa than from Central Africa