A Different Molecular Pattern of β‐Thalassemia Mutations in Northeast Brazil

Abstract

The main hereditary hemoglobin (Hb) disorders of clinical significance in Brazil are sickle cell disease and β‐thalassemia (thal). The sickle gene was introduced by the slave trade, whereas β‐thal was introduced later, due to a massive immigration (mostly by Italians) between 1870 and 1953, mainly to the southeast region of Brazil. Molecular studies performed in the southeast of the country showed a marked prevalence of the nonsense mutation at codon 39 (C → T) (47–54%), leading to severe forms of β⁰‐thal. However, the northeast region of the country has a different demographic history, characterized by the absence of the massive Italian immigration. Owing to this and since the majority of cases of β‐thal in Pernambuco, a state located in the northeast of the country, have mild or intermediate clinical and laboratory features, we would predict a different spectrum of β‐thal mutations in this region. We examined 60 unrelated patients (86 β‐thal chromosomes) under regular clinical follow‐up in Pernambuco: 6 were regularly transfused β‐thal major subjects, 20 had β‐thal intermedia, 20 had Hb S/β‐thal and 14 were β‐thal trait individuals. The following mutations were found: IVS‐I‐6 (T → C) 62.8%, IVS‐I‐1 (G → A) 15.1%, IVS‐I‐5 (G → C) 9.3%, IVS‐I‐110 (G → A) 8.2%, codon 39 (C → T) 3.5%, and codon 30 (AGG → AGC) 1.1%. These data show different patterns of β‐thal mutations in two regions of Brazil, demonstrating a thus far unrevealed heterogeneity of the disease in the country.

• Thalassemia
• Hemoglobin
• β‐Globin mutations
• Brazil