Browsing by Author "Pena, Rita"
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- Ancestry of the major long-range regulatory site of the α-globin genes in the Portuguese population with the common 3.7 kb α-thalassemia deletionPublication . Pena, Rita; Lopes, Pedro; Gaspar, Gisela; Miranda, Armandina; Faustino, PaulaBackground: The α-Major Regulatory Element (α-MRE), also known as HS-40, is located upstream of the α-globin gene cluster and has a crucial role in the long-range regulation of the α-globin gene expression. This enhancer is polymorphic and several haplotypes were identified in different populations, with haplotype D almost exclusively found in African populations. The purpose of this research was to identify the HS-40 haplotype associated with the 3.7 kb α-thalassemia deletion (-α3.7del) in the Portuguese population, and determine its ancestry and influence on patients' hematological phenotype. Methods and results: We selected 111 Portuguese individuals previously analyzed by Gap-PCR to detect the presence of the -α3.7del: 50 without the -α3.7del, 34 heterozygous and 27 homozygous for the -α3.7del. The HS-40 region was amplified by PCR followed by Sanger sequencing. Four HS-40 haplotypes were found (A to D). The distribution of HS-40 haplotypes and genotypes are significantly different between individuals with and without the -α3.7del, being haplotype D and genotype AD the most prevalent in patients with this deletion in homozygosity. Furthermore, multiple correspondence analysis revealed that individuals without the -α3.7del are grouped with other European populations, while samples with the -α3.7del are separated from these and found more closely related to the African population. Conclusion: This study revealed for the first time an association of the HS-40 haplotype D with the -α3.7del in the Portuguese population, and its likely African ancestry. These results may have clinical importance as in vitro analysis of haplotype D showed a decrease in its enhancer activity on α-globin gene.
- Ancestry of the major long-range regulatory site of the α-globin genes in the Portuguese population with the common 3.7kb α-thalassemia deletionPublication . Pena, Rita; Lopes, Pedro; Gaspar, Gisela; Miranda, Armandina; Faustino, PaulaThe α-major regulatory element (known as HS-40) has a crucial role in the long-range regulation of the α-globin gene expression. This element is genetically polymorphic and six haplotypes (A to F) have been identified in different populations, with haplotype D almost exclusively found in African populations. This study aimed to identify the HS-40 haplotype associated with the common 3.7kb α-thalassemia deletion (-α3.7del) in the Portuguese population, and investigate its ancestry. We searched for the -α3.7del in 111 selected Portuguese individuals by Gap-PCR. In addition, a DNA fragment containing the HS-40 was amplified by PCR and Sanger sequenced. Statistical analysis was performed using R software. Fifty individuals have the wild-type α-globin genotype (group I), 34 are heterozygous for the -α3.7del (group II) and 27 are homozygous (group III). Regarding the HS-40, four haplotypes were found (A to D). The distribution of HS-40 haplotypes and genotypes are significantly different between groups with and without the -α3.7del (p<0.001), being haplotype D and genotype AD the most prevalent in group III. Furthermore, multiple correspondence analysis revealed that individuals without the -α3.7del are grouped with other European populations, while samples with the -α3.7del are split from these and found more related to the African population. This study revealed for the first time an association of a specific HS-40 haplotype with the -α3.7del in the Portuguese population, and its likely African ancestry. These results may have a clinical importance as in vitro analysis of haplotype D showed a descrease in its enhancer activity on α-globin genes.
- Ancestry of the α-MRE Associated with the 3.7kb α-Thalassemia Deletion in the Portuguese PopulationPublication . Pena, Rita; Lopes, Pedro; Gaspar, Gisela; Miranda, Armandina; Faustino, PaulaThe α-major regulatory element (α-MRE), also known as HS-40, is located upstream of the α-globin gene cluster and has a crucial role in the long-range regulation of the α-globin gene expression. It is genetically polymorphic and six haplotypes (A to F) have been identified in different populations. The D haplotype was primary described in African populations and is nearly absent in other populations. The aims of this study were to identify the α-MRE haplotype associated with the common 3.7kb α-thalassemia deletion (-α3.7del) in the Portuguese population, and to investigate its ancestry. We searched for the -α3.7del in 111 selected Portuguese individuals by Gap-PCR. In addition, a DNA fragment containing the α-MRE was amplified by PCR and Sanger sequenced. Statistical analysis was performed using R software. Fifty individuals have the wild-type α-globin genotype (group I), 34 are heterozygous for the -α3.7del (group II) and 27 are homozygous (group III). Regarding the α-MRE, four haplotypes were found (A to D). The ancestral A haplotype is predominant in all groups. The B haplotype is the second most frequent in groups I and II, whereas in group III haplotype D is the second most prevalent. Concerning genotypes, the α-MRE AA and AB are the most common in group I, while genotype AD is more prevalent in group III. In fact, 71.4% of AD individuals are homozygous for the -α3.7del. Moreover, the distribution of α-MRE haplotypes and genotypes are significantly different between groups with and without the -α3.7del (p<0.001). Furthermore, multiple correspondence analysis revealed that individuals without the -α3.7del are grouped with other European populations, while samples with the -α3.7del are split from these and found to be more closely related to the African population. This study revealed for the first time an association of a specific α-MRE haplotype with the common -α3.7del in the Portuguese population, and its likely African ancestry. These results may have clinical importance as the D haplotype has an alteration in the consensus sequence for the AP-1/NF-E2 binding site and in vitro experiments showed a decrease in its enhancer activity on α-globin genes.