Southeast Asian diversity: first insights into the complex mtDNA structure of Laos

<p>Abstract</p> <p>Background</p> <p>Vast migrations and subsequent assimilation processes have shaped the genetic composition of Southeast Asia, an area of close contact between several major ethnic groups. To better characterize the genetic variation of this region, we analyzed the entire mtDNA control region of 214 unrelated donors from Laos according to highest forensic quality standards. To detail the phylogeny, we inspected selected SNPs from the mtDNA coding region. For <it>a posteriori </it>data quality control, quasi-median network constructions and autosomal STR typing were performed. In order to describe the mtDNA setup of Laos more thoroughly, the data were subjected to population genetic comparisons with 16 East Asian groups.</p> <p>Results</p> <p>The Laos sample exhibited ample mtDNA diversity, reflecting the huge number of ethnic groups listed. We found several new, so far undescribed mtDNA lineages in this dataset and surrounding populations. The Laos population was characteristic in terms of haplotype composition and genetic structure, however, genetic comparisons with other Southeast Asian populations revealed limited, but significant genetic differentiation. Notable differences in the maternal relationship to the major indigenous Southeast Asian ethnolinguistic groups were detected.</p> <p>Conclusions</p> <p>In this study, we portray the great mtDNA variety of Laos for the first time. Our findings will contribute to clarify the migration history of the region. They encourage setting up regional and subpopulation databases, especially for forensic applications. The Laotian sequences will be incorporated into the collaborative EMPOP mtDNA database <url>http://www.empop.org</url> upon publication and will be available as the first mtDNA reference data for this country.</p

α-thalassaemia

Alpha-thalassaemia is inherited as an autosomal recessive disorder characterised by a microcytic hypochromic anaemia, and a clinical phenotype varying from almost asymptomatic to a lethal haemolytic anaemia

RAPID DETECTION OF -THALASSEMIA MUTATIONS IN THAILAND USING MULTIPLEX ARMS

The number of mutations underlining b-thalassemia generate a wide variety of different clinical phenotypes. An understanding of the genotype is important for medical personnel in order to provide proper counseling to patients and their families. Characterization of these mutations should aid the planning of a prenatal diagnosis program for bthalassemia. The heterogeneity of the mutations makes it difficult and time consuming to identify the mutation in some individuals. We developed a single-tube multiplex amplification refractory mutation system (multiplex ARMS) to identify common ethnic- specific b-thalassemia mutations. Confirmation of multiplex ARMS results was carried out using direct sequencing. Three thousand three hundred twenty two people from Phitsanulok province were screened for the b-thalassemia trait by quantitation of HbA2 with microcolumn chromatography and the genotypes of mutations were characterized using multiplex ARMS and direct sequencing. We found that the deletion at codons 41/42 (-TCTT) was the most frequent (48%), codon 17 (A®T) (30%), -28 (A®G) (6%) and IVS-I-1(G®T) (6%) were the second and third in frequency respectively. A -87 (C®A) mutation (4%), IVS II-654 (C®T) (2%), codons 71/72 (+A) (2%) and codon 35 (C®A) mutations (2%) were also found. These techniques were found to be a valuable tool for analysis of b-thalassemia mutations because they are accurate, simple, and speedy in operation. The application for the diagnosis of severe thalassemia in high-risk pregnancies is promising

RAPID DETECTION OF -THALASSEMIA MUTATIONS IN THAILAND USING MULTIPLEX ARMS

The number of mutations underlining b-thalassemia generate a wide variety of different clinical phenotypes. An understanding of the genotype is important for medical personnel in order to provide proper counseling to patients and their families. Characterization of these mutations should aid the planning of a prenatal diagnosis program for bthalassemia. The heterogeneity of the mutations makes it difficult and time consuming to identify the mutation in some individuals. We developed a single-tube multiplex amplification refractory mutation system (multiplex ARMS) to identify common ethnic- specific b-thalassemia mutations. Confirmation of multiplex ARMS results was carried out using direct sequencing. Three thousand three hundred twenty two people from Phitsanulok province were screened for the b-thalassemia trait by quantitation of HbA2 with microcolumn chromatography and the genotypes of mutations were characterized using multiplex ARMS and direct sequencing. We found that the deletion at codons 41/42 (-TCTT) was the most frequent (48%), codon 17 (A®T) (30%), -28 (A®G) (6%) and IVS-I-1(G®T) (6%) were the second and third in frequency respectively. A -87 (C®A) mutation (4%), IVS II-654 (C®T) (2%), codons 71/72 (+A) (2%) and codon 35 (C®A) mutations (2%) were also found. These techniques were found to be a valuable tool for analysis of b-thalassemia mutations because they are accurate, simple, and speedy in operation. The application for the diagnosis of severe thalassemia in high-risk pregnancies is promising

Associations of Common -Thalassemia Mutations With -Globin Gene Frameworks in Northern Thailand

This study aimed to characterize polymorphism of the b-globin gene (framework) among common b-thalassemia mutations found in northern Thailand. Thirty-one homozygous b-thalassemia major patients admitted to Chiang Mai University Hospital were identified using direct DNA sequencing method. Among 15 patients with homozygous of codon 41/42 (-TCTT), eight were homozygous of framework 1 (FW1), one was homozygous of FW3A, and the remainders were heterozygous of FW1 and FW3A. The gene frequencies of FW1 and FW3A in the patients were 0.733 (22/ 30) and 0.267 (8/30), respectively. All 11 patients with homozygous of codon 17 (A-T) were homozygous of FW3A, while three patients with homozygous of intron 1 nt 1 (G-T) were homozygous of FW1. Both patients with homozygous of codon 71/72 (+A) were FW3A. In this report, the numbers of b-globin gene frameworks were restricted in each b-thalassemia mutation. This investigation may provide further information for the study of the evolution of common mutations causing b-thalassemia major in northern Thailand