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Hemoglobin S is caused by a nucleotide change in HBB gene (HBB:c.20A>T, p.Glu6Val), is presented in diverse forms: simple carriers (HbSA), homozygotes (HbSS) also known as sickle cell anemia, and compound heterozygotes with other β-hemoglobinopathies. It is worldwide distributed, in Mexico, is frequently observed in the southern states Guerrero, Oaxaca and Chiapas. Elevated fetal hemoglobin (HbF) is associated with mild phenotype; single-nucleotide variants (SNVs) in modifier genes, such as BCL11A, HBG2, HBBP1 pseudogene and HBS1L-MYB intergenic region, upregulate HbF synthesis. The aim of this study was to identify HbF regulating genetic variants in HbSS and HbSA Mexican subjects. We studied 39 individuals (HbSS = 24, 61%, HbSA = 15, 39%) from Chiapas (67%) and Guerrero (33%), peripheral blood was collected in ethylenediamine tetraacetic acid (EDTA) for molecular and hematological studies, DNA was isolated by salting-out technic and genotyping was performed through allelic discrimination by real time polymerase chain reaction (RT-PCR) using Taqman® probes for 15 SNV (in BCL11A: rs6706648, rs7557939, rs4671393, rs11886868, rs766432, rs7599488, rs1427407; HBS1L-MYB: rs28384513, rs7776054, rs9399137, rs4895441, rs9402686, rs1320963; HBG2: rs7482144; and HBBP1: rs10128556). The obtained data were analyzed using IMB SPSS v.22.0 software. All minor alleles were observed in frequencies over 0.05, the most frequent was rs9402686 (0.82), while the less frequent was rs101028556 (0.08). In HbSS group, the mean fetal hemoglobin was 11.9 ± 5.9% and was significantly elevated in BCL11A rs11886868 wildtype homozygotes and in carriers of HBS1L-MYB intergenic region rs7776054 (p = 0.04 and p = 0.03, respectively). In conclusion, in HbSS Mexican patients, two SNVs were observed related to increased HbF; BCL11A rs11886868 and HBS1L-MYB rs7776054. [ABSTRACT FROM AUTHOR]

Introduction Beta-thalassemia (β-thal) is frequent in Mexican patients with microcytosis and hypochromia. We report three novel mutations and analyze the actual mutational spectrum in Mexican population. Methods One hundred and forty-nine β-thal Mexican mestizo patients were studied (154 alleles). ARMS- PCR was performed to identify Cd39C>T, IVS1:1G>A, IVS1:110G>A, -28A>C, initiation codonA>G and IVS1:5G>A mutations, and gap- PCR for δβ-thal Spanish type. DNA sequencing of HBB gene was carried out in negative samples for the initial screening. Results Fifteen different HBB gene mutations were observed in 148 alleles; three of them are novel: -90C>G, 20 bp deletion (at codons 78/85), and IVS2:2T>G; the mutation IVS1:6T>C that was observed for first time in our population; and eleven previously described mutations. Six alleles showed normal HBB sequence. To date, a total of 21 different mutations have been observed in Mexican patients; the four most frequent mutations are of Mediterranean origin: Cd39C>T (37.2%), IVS1:1G>A (17.3%), IVS1:110G>A (13.9%), and δβ-thal Spanish type (9.0%), which represent 77.4% of the total studied alleles. Conclusion Considering the novel mutations -90C>G, -20 bp Cd78/85, IVS2:2T>G and the first observation of IVS1:6T>C, the molecular spectrum of β-thal in Mexicans comprises 21 different mutations, confirming the high allelic heterogeneity in Mexicans. [ABSTRACT FROM AUTHOR]

Introduction Alpha-thalassemia (α-thal) is a common monogenic disorder worldwide. In mixed ethnic populations, α-thal and beta-thalassemia (β-thal) can be expected, sometimes giving complex phenotypes, which without molecular analysis are not easily explained. We performed the molecular identification of α- and β-thal alleles in 51 Mexican patients with microcytosis, hypochromia, and normal or low levels of HbA2. Methods Common deletional alleles (-α3.7, -α4.2, - - SEA, - - MED, - - FIL, - - THAI, -α20.5) and α-triplication were studied by gap- PCR and nondeletional alleles (α IVSI(−5nt), α2NcoI, α1NcoI) by ARMS. β-thal alleles Cd39 (C>T), IVS1:1 (G>A), IVS1:110 (G>A), and Spanish δβ-thal were also investigated. DNA sequencing was performed on HBA2, HBA1, and HBB genes. Negative samples were subjected to MLPA. Results In 35 subjects, we identified the mutations, -α3.7, - - SEA, - - FIL, α IVSI(−5nt), and αααanti3.7 and two novel deletion alleles - -Mex1 (6.8-8.9 kb) and - -Mex2 (77.6-135.7 kb). Four individuals also had a β-thal allele (Cd39/ IVS1:110). No α-thal alleles were observed in 16 subjects, but three had a β-thal mutation Cd39, IVS1:110, and Spanish δβ-thal. Conclusion α-thal is relatively common in Mexican patients, the combination with β-thal is sometimes unexpected, and this underlines the importance of performing molecular analysis for both α- and β-genes defects in patients showing microcytic hypochromic anemia. [ABSTRACT FROM AUTHOR]

Introduction Alpha-thalassemia (α-thal) is a common monogenic disorder worldwide. In mixed ethnic populations, α-thal and beta-thalassemia (β-thal) can be expected, sometimes giving complex phenotypes, which without molecular analysis are not easily explained. We performed the molecular identification of α- and β-thal alleles in 51 Mexican patients with microcytosis, hypochromia, and normal or low levels of HbA2. Methods Common deletional alleles (-α3.7, -α4.2, - - SEA, - - MED, - - FIL, - - THAI, -α20.5) and α-triplication were studied by gap- PCR and nondeletional alleles (α IVSI(−5nt), α2NcoI, α1NcoI) by ARMS. β-thal alleles Cd39 (C>T), IVS1:1 (G>A), IVS1:110 (G>A), and Spanish δβ-thal were also investigated. DNA sequencing was performed on HBA2, HBA1, and HBB genes. Negative samples were subjected to MLPA. Results In 35 subjects, we identified the mutations, -α3.7, - - SEA, - - FIL, α IVSI(−5nt), and αααanti3.7 and two novel deletion alleles - -Mex1 (6.8-8.9 kb) and - -Mex2 (77.6-135.7 kb). Four individuals also had a β-thal allele (Cd39/ IVS1:110). No α-thal alleles were observed in 16 subjects, but three had a β-thal mutation Cd39, IVS1:110, and Spanish δβ-thal. Conclusion α-thal is relatively common in Mexican patients, the combination with β-thal is sometimes unexpected, and this underlines the importance of performing molecular analysis for both α- and β-genes defects in patients showing microcytic hypochromic anemia. [ABSTRACT FROM AUTHOR]

Hemoglobin S is caused by a nucleotide change in HBB gene (HBB:c.20A>T, p.Glu6Val), is presented in diverse forms: simple carriers (HbSA), homozygotes (HbSS) also known as sickle cell anemia, and compound heterozygotes with other β-hemoglobinopathies. It is worldwide distributed, in Mexico, is frequently observed in the southern states Guerrero, Oaxaca and Chiapas. Elevated fetal hemoglobin (HbF) is associated with mild phenotype; single-nucleotide variants (SNVs) in modifier genes, such as BCL11A, HBG2, HBBP1 pseudogene and HBS1L-MYB intergenic region, upregulate HbF synthesis. The aim of this study was to identify HbF regulating genetic variants in HbSS and HbSA Mexican subjects. We studied 39 individuals (HbSS = 24, 61%, HbSA = 15, 39%) from Chiapas (67%) and Guerrero (33%), peripheral blood was collected in ethylenediamine tetraacetic acid (EDTA) for molecular and hematological studies, DNA was isolated by salting-out technic and genotyping was performed through allelic discrimination by real time polymerase chain reaction (RT-PCR) using Taqman® probes for 15 SNV (in BCL11A: rs6706648, rs7557939, rs4671393, rs11886868, rs766432, rs7599488, rs1427407; HBS1L-MYB: rs28384513, rs7776054, rs9399137, rs4895441, rs9402686, rs1320963; HBG2: rs7482144; and HBBP1: rs10128556). The obtained data were analyzed using IMB SPSS v.22.0 software. All minor alleles were observed in frequencies over 0.05, the most frequent was rs9402686 (0.82), while the less frequent was rs101028556 (0.08). In HbSS group, the mean fetal hemoglobin was 11.9 ± 5.9% and was significantly elevated in BCL11A rs11886868 wildtype homozygotes and in carriers of HBS1L-MYB intergenic region rs7776054 (p = 0.04 and p = 0.03, respectively). In conclusion, in HbSS Mexican patients, two SNVs were observed related to increased HbF; BCL11A rs11886868 and HBS1L-MYB rs7776054., (© The Author(s) [2022]. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: The purpose of this study was to determine the β-globin cluster haplotype variability of two Mexican indigenous groups-Purepechas (PUR) and Tarahumaras (TAR)-and their relationship with other world populations., Methods: The 5' and 3' haplotypes (Hp) of the β globin cluster in 71 PUR and 53 TAR individuals were analyzed. Five polymorphisms in the 5'Hp (ε, (G) γ, (A) γ, 5'ψβ and 3'ψβ) and five in the 3'Hp (IVS2: 16, 46, 74, 81 and 3' end +339) were identified by restriction enzymes and direct DNA sequencing. 5'Hp and 3'Hp frequencies in PUR and TAR were compared with reported frequencies from 47 and 10 worldwide populations, respectively., Results: Sixteen different 5'Hps were observed in the indigenous Mexican groups, 11 in each population, with the most common being 5'Hp 1. Eight 3'Hps were detected, seven in PUR and six in TAR, the most frequent being 3'Hp C. Three new 3'Hps were found, A8 (CTGCT) in both populations, C9 (GTGCA) in TAR and E1 (GTTCT) in PUR. The comparative analysis showed that 5'Hp frequencies in PUR were significantly different than those in all populations except the Brazilian-Guarani, while TAR were significantly similar to Aché and North Han Chinese. 3'Hp frequencies were similar between PUR and TAR, as well as with Nuu-Chah-Nulth, Mongolian and Sumatran populations., Conclusions: The 5'Hp analysis showed great variability in worldwide populations, including PUR and TAR, while 3'Hp frequencies were similar among indigenous Mexican and other populations with Asiatic origins. This suggests that 5'Hp exposes the microevolutionary process of each population and the 3'Hp establishes genetic relationships among populations., (© 2015 Wiley Periodicals, Inc.)