Reduced rate of sickle-related complications in Brazilian patients carrying HbF-promoting alleles at the BCL11A and HMIP-2 loci.

The presence of high levels of fetal haemoglobin (HbF) provides well-validated clinical benefits to patients with sickle cell anaemia (SCA). Nevertheless it has been difficult to show clear direct effects of the known genetic HbF modifiers, such as the enhancer polymorphisms for haematopoietic transcription factors BCL11A and MYB, on SCA severity. Investigating SCA patients from Brazil, with a high degree of European genetic admixture, we have detected strong effects of these variants on HbF levels. Critically, we have shown, for the first time, that the presence of such HbF-promoting variants leads to a reduced rate of SCA complications, especially stroke.

Deferasirox associated with liver failure and death in a sickle cell anemia patient homozygous for the -1774delG polymorphism in the Abcc2 gene.

This manuscript describes the case of a patient with sickle cell anemia who died of fulminant hepatitis after therapy with the iron chelator Deferasirox. The patient was homozygous for the -1774delG polymorphism in the Abcc2 gene, which raises the concern about the use of hepatotoxic drugs in this specific context.

Identification of beta thalassemia mutations in South Brazilians.

We have evaluated the mutation profile in a sample of 127 unrelated beta-thalassemia (beta thal) individuals, diagnosed through A2 and fetal hemoglobin quantification by high-performance liquid chromatography (HPLC) from the Brazilian southernmost state, where a flow of Italian immigrants had occurred in the late 19th century, mainly from Northern Italy. The molecular analysis was performed by DNA sequencing of the most common mutations found in the Mediterranean region. The beta 0 codon 39 nonsense mutation was the most frequent alteration (50.9%), followed by beta+ IVSI 110 G>A (18.1%), beta 0 IVSI 1 G>A (12.9%), beta+ IVSI 6 T>C (9.5%), and other rare mutations (8.6%). The chosen gene sequence was able to identify 91% beta-thal mutations in the population studied, showing some similarity with allele frequencies of the mainly colonizing countries of Rio Grande do Sul state. The comparison of our results to other Brazilian studies has shown significant differences. Therefore, we can conclude that the genotypic profile of beta-thal shows great variability. Hence, it would be arbitrary to infer regional study results as being representative of the Brazilian whole population. Brazilian researchers of different regions should identify their most frequent genotypes to provide better understanding on this disease and state adequate public health policies.

DNAase I hypersensitive site 3' to the beta-globin gene cluster containing two TAA insertions and a G-->A polymorphism is predominantly associated with the beta+-thalassemia IVS-I-6 (T-->C) mutation.

Analysis of DNA polymorphic sites is an important tool for the detection of gene flow in human evolutionary studies and to study the genetic background for gene mutations. The beta-globin locus contains several single-base restriction fragment length polymorphism (RFLP) sites throughout chromosome 11. In addition to these polymorphic sequence repeats, others are being studied in order to expand our knowledge concerning the role between haplotype-genotype and phenotype associations. Far downstream of the expressed beta-globin genes, there is a hypersensitive site (HS) whose function remains obscure. We sequenced this region in 27 thalassemia patients and found a new pattern in the micro-satellite-like AT-rich region of this site: a new TAA insertion in addition to the one previously described in sickle cell patients with a concomitant polymorphism (G-->A). This new variation was found to be linked to the IVS-I-6 (T-->C) mutation. This polymorphism may be useful for studies concerning genotype and phenotype associations.