Beta-globin gene cluster haplotypes in Afro-Uruguayans from two geographical regions (South and North)

To Study the β-Globin Haplotype Pattern of Descent of a Set of Linked Alleles Occurring on the Same Chromosome in the Northern Province of India

OBJECTIVE

To study the five mutations commonly prevalent in North India, i.e., IVS-I-5 (G→C), 619 bp deletion, IVS-I-1 (G→T), codon 41/42 (-TTCT), and codon 8/9 (+G), in the beta thalassemia (β-thalassemia) major children. The specific β-thalassemia mutations of different haplotype patterns of the β-globin gene cluster will also be determined.

METHODS

A total of 125 children diagnosed with β-thalassemia major visiting the Department of Pediatrics of King George's Medical University were involved in the study. As per the QIAamp (Qiagen, Hilden, Germany) manufacturer guidelines, genomic DNA was isolated from whole blood. To identify the haplotype pattern within the β-globin gene cluster, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used. The respective restriction endonucleases used were Hind III/GƔ, Hinc II/Ψß, Hinf I/ß, Ava II/ß, and BamHI for the haplotype analysis in the β-globin pattern of descent of a set of linked alleles occurring on the same chromosome.

RESULTS

Among the five common mutations, 73 patients had IVS-I-5 (G→C), 28 patients had 619 bp deletion, 17 patients had IVS-I-1 (G→T), five patients had Cd 41/42 (-TTCT), and two patients had Cd 8/9 (+G) mutations. Fifteen haplotypes (haplotypes 1-15) were identified in 125 β-thalassemia major children. Among the five haplotypes observed in the IVS-I-5 (G→C) mutation, the H1 haplotype was most predominant with a frequency of 27.2%, followed by the H2, H4, H3, and H10 haplotypes in the given population. In 619 bp deletion, IVS-I-1 (G→T), codon 41/42, and codon 8/9, haplotype H9, H12, H11, and H5 were seen, respectively.

CONCLUSION

β-thalassemia was found to be the most common in the northern province of Uttar Pradesh. The linkage of β-globin gene haplotypes with β-thalassemia mutations was explored in the northern province of Uttar Pradesh. The population of different natives is being mixed up due to migration and industrialization. These were some reasons for the occurrence of haplotypic heterogeneity. This haplotype heterogeneity was correlated with the origin of these mutations found to be unlike the origin of common ones from different provinces.

Genomic Diversity in Sporadic Breast Cancer in a Latin American Population

Among Latin American women, breast cancer incidences vary across populations. Uruguay and Argentina have the highest rates in South America, which are mainly attributed to strong, genetic European contributions. Most genetic variants associated with breast cancer were described in European populations. However, the vast majority of genetic contributors to breast cancer risk remain unknown. Here, we report the results of a candidate gene association study of sporadic breast cancer in 176 cases and 183 controls in the Uruguayan population. We analyzed 141 variants from 98 loci that have been associated with overall breast cancer risk in European populations. We found weak evidence for the association of risk variants rs294174 (ESR1), rs16886165 (MAP3K1), rs2214681 (CNTNAP2), rs4237855 (VDR), rs9594579 (RANKL), rs8183919 (PTGIS), rs2981582 (FGFR2), and rs1799950 (BRCA1) with sporadic breast cancer. These results provide useful insight into the genetic susceptibility to sporadic breast cancer in the Uruguayan population and support the use of genetic risk scores for individualized screening and prevention.

Haplotype Analysis of β-Thalassaemia Major and Carriers with Filipino β°-Deletion in Sabah, Malaysia

OBJECTIVE

The Filipino β°-deletion has been reported as a unique mutation in East Malaysia with a severe phenotype due to the complete absence of β-globin chain synthesis. In this study, the haplotype patterns of the β-globin gene cluster were used to relate the human genetic variation to this specific β-thalassaemia mutation.

METHODS

The 376 study subjects included 219 β-thalassaemia major (β-TM) patients with homozygous Filipino β°-deletion and 157 carriers with heterozygous Filipino β°-deletion from 10 government hospitals in different regions of Sabah. Genomic DNA was isolated from whole blood using silica membrane based DNA purification protocol. Polymerase chain reaction restriction fragment length polymorphism analysis (PCR-RFLP) was conducted on five markers within the β-globin gene cluster to construct the haplotype patterns.

RESULTS

Four haplotypes (Haplotype I-IV) were identified with Haplotype I as the predominant haplotype with the highest frequency of 0.98, followed by Haplotype II, III and Haplotype IV with 0.02. Haplotype I was strongly linked with the Filipino β°-deletion among the indigenous population.

CONCLUSION

Haplotype I as the predominant haplotype suggests the patients with the Filipino β°-deletion in Sabah have a similar origin.

Interethnic admixture and the evolution of Latin American populations

A general introduction to the origins and history of Latin American populations is followed by a systematic review of the data from molecular autosomal assessments of the ethnic/continental (European, African, Amerindian) ancestries for 24 Latin American countries or territories. The data surveyed are of varying quality but provide a general picture of the present constitution of these populations. A brief discussion about the applications of these results (admixture mapping) is also provided. Latin American populations can be viewed as natural experiments for the investigation of unique anthropological and epidemiological issues.