Molecular Characterization and Phenotypical Study of b-Thalassemia in Tucuman, Argentina

Abstract

The main hereditary hemoglobin (Hb) disorder in Argentina is b-thalassemia (b-thal). Molecular studies performed in the center of the country exhibited a marked prevalence of the codon 39 (C4T) and IVS-I-110 (G4A) mutations. The northwest region of Argentina has a different demographic history characterized by an important Spanish influx. Seventy-one b-thal carriers attending the Instituto de Bioquı´mica Aplicada, Tucuma´n, Argentina, were investigated for b-globin gene mutations by real-time polymerase chain reaction (RT-PCR). To examine the genotype-phenotype relationship, mean corpuscular volume (MCV), mean corpuscular Hb (MCH) and Hb A2 were measured. In order to recognize b-thal, Mentzer Index, Shine & Lal and Red Cell Distribution Width Index (RDWI), were calculated. The ethnic background of subjects revealed that 82.0% of the population was of Italian, Spanish and Arab origin. Seven mutations were detected: codon 39 (45.0%), IVS-I-1 (G4A) (22.5%), IVS-I-110 (16.3%), IVS-II-1 (G4A) (4.1%), IVS-I-1 (G4T) (2.0%), IVS-I-6 (T4C) (2.0%) and IVS-II-745 (G4C) (2.0%). In three families (6.1%), b-thal mutations were not determined. These results differed from other Argentinian studies because at present codon 39 and IVS-I-1 are the most prevalent; MCV, MCH and Hb A2 did not correlate with the type of mutation (b0/b+). Values of MCV (67.0 fL) and Hb A2 (4.85%) were unable to discriminate between them. Significant differences (p50.05) in MCV, MCH and Shine & Lal were observed between the undetermined group and the three most common mutations. These data show different patterns of b-thal mutations in the center and northwest regions of Argentina. Differences might represent the influence of Spanish immigration.