A survey of the genetic ancestry of 125 Cambodian children resident in Siem Reap province was undertaken, based on eight Y-chromosome binary polymorphisms and sequencing of the mtDNA HV1 region. The data indicated a largely East Asian paternal ancestry and a local Southeast Asian maternal ancestry. The presence of Y-chromosomes P* and R1a1* was suggestive of a small but significant Indo-European male ancestral component, which probably reflects the history of Indian, and later European, influences on Cambodia.

Alpha-thalassaemia and HbE have been reported to occur at high frequency (80%) in children with hypochromic microcytic anaemia from Siem Reap. In addition, HbPS has been reported from this region. The study aims to document the prevalence of anaemia, a- and b- thalassaemia and other haemoglobinopathies in children presenting sequentially to the Angkor Hospital for Children. Two hundred and sixty children between 5 months and 16 years of age were assessed with full blood counts, films, ferritin levels, HPLC, a-globin multiplex PCR and b-globin PCR. 110 anaemic subjects were identified with 61 cases of microcytic anaemia. Six subjects were iron deficient. 163 children (63%) had a haemoglobinopathy. The high prevalence of HbE (29%) in the study population is consistent with previous reports. By comparison b-thalassaemia (0.7%) occurs at lower frequency than previously reported. Alpha-thalassaemia occurs at high frequency (35.4% of subjects), but a large majority of subjects (78%) have a single gene deletion, with double deletions occurring at low frequency (5%). HbPS occurs at low frequency whilst the frequency of triplicated a genes in the survey population is consistent with that described in other populations. Although haemoglobinopathies are common in Cambodian children, the majority of abnormalities (heterozygous HbE and a3.7) are clinically insignificant. Only 2 cases with clinically severe haemoglobinopathy (HbH disease and Eb thalassaemia) were identified.

The joint application of different molecular marker systems, such as microsatellites, SNPs and mtDNA sequences, in concert with computationally intensive model-based techniques, is allowing the development of an increasingly complex picture of human genetic history. With >1,100 million Han and 55 officially recognized minority populations accounting for another 100+ million people, PR China represents an example of such complexity. For this study, DNA samples from the majority Han, seven official minorities in north, south, west and central China, the Hui, Miao, Yao, Tibetans, Boan, Dongxiang and Salar, and one unofficial minority, the Kuchong, were collected. The samples were analysed with autosomal, Y-chromosome and mtDNA markers that had differing mutation behaviours, and the resultant molecular data then compared with known historical, archaeological and demographic information. Strong evidence for the temporal stratification of human migration in China was established from the molecular data, spanning the first human migrations into East Asia to recent historical migrations along the Silk Road. Data on internal population structure can be added to this evidence using computationally intensive model-based techniques, thus allowing researchers to include the influence of factors such as endogamy when considering the effect of population stratification in future human genetic studies.

The identification of a growing number of novel Mendelian disorders and private mutations in the Roma (Gypsies) points to their unique genetic heritage. Linguistic evidence suggests that they are of diverse Indian origins. Their social structure within Europe resembles that of the jatis of India, where the endogamous group, often defined by profession, is the primary unit. Genetic studies have reported dramatic differences in the frequencies of mutations and neutral polymorphisms in different Romani populations. However, these studies have not resolved ambiguities regarding the origins and relatedness of Romani populations. In this study, we examine the genetic structure of 14 well-defined Romani populations. Y-chromosome and mtDNA markers of different mutability were analyzed in a total of 275 individuals. Asian Y-chromosome haplogroup VI-68, defined by a mutation at the M82 locus, was present in all 14 populations and accounted for 44.8% of Romani Y chromosomes. Asian mtDNA-haplogroup M was also identified in all Romani populations and accounted for 26.5% of female lineages in the sample. Limited diversity within these two haplogroups, measured by the variation at eight short-tandem-repeat loci for the Y chromosome, and sequencing of the HVS1 for the mtDNA are consistent with a small group of founders splitting from a single ethnic population in the Indian subcontinent. Principal-components analysis and analysis of molecular variance indicate that genetic structure in extant endogamous Romani populations has been shaped by genetic drift and differential admixture and correlates with the migrational history of the Roma in Europe. By contrast, social organization and professional group divisions appear to be the product of a more recent restitution of the caste system of India.