Adherence to a traditional lifestyle affects food and nutrient intake among modern Swedish Sami.

OBJECTIVES: To compare the nutrient and food intake of Sami still engaged in reindeer herding (traditional lifestyle or reindeer-herding Sami [RS]) and Sami not involved in reindeer herding (industrialized lifestyle or non-reindeer-herding Sami [NRS]) with other northern Swedish populations. STUDY DESIGN: Cross-sectional analysis of data from a prospective cardiovascular intervention program in northern Sweden. METHODS: Data were used from a prospective cardiovascular intervention program in northern Sweden. Sami recruited into this study were divided according to whether they were involved in reindeer herding (traditional lifestyle, RS) (66 females, 79 males) or not (NRS) (255 females, 195 males), and compared to non-Sami from the same area taking part in the same study (controls) (499 females, 501 males). Subjects completed a Food Frequency Questionnaire (FFQ) and clinical parameters were analysed. RESULTS: RS had a higher overall intake of energy for both females (P<0.01) and males (P<0.05), but not total food intake compared to controls and NRS. The overall Sami diet was characterized by a higher proportion of energy from protein and fat. RS had a lower energy adjusted intake of vitamins A and E, and fibre, and higher intake of sodium. RS and NRS both had a lower intake of vegetables and a higher intake of meat, and for RS, fish. Nutrient and food-intake patterns were similar for males and females. CONCLUSIONS: Classification of Sami into RS and NRS indicates that a traditional lifestyles defined by occupation is reflected in differences in food and nutrient intake.

Evaluation of the SNP tagging approach in an independent population sample--array-based SNP discovery in Sami.

Significant efforts have been made to determine the correlation structure of common SNPs in the human genome. One method has been to identify the sets of tagSNPs that capture most of the genetic variation. Here, we evaluate the transferability of tagSNPs between populations using a population sample of Sami, the indigenous people of Scandinavia. Array-based SNP discovery in a 4.4 Mb region of 28 phased copies of chromosome 21 uncovered 5,132 segregating sites, 3,188 of which had a minimum minor allele frequency (mMAF) of 0.1. Due to the population structure and consequently high LD, the number of tagSNPs needed to capture all SNP variation in Sami is much lower than that for the HapMap populations. TagSNPs identified from the HapMap data perform only slightly better in the Sami than choosing tagSNPs at random from the same set of common SNPs. Surprisingly, tagSNPs defined from the HapMap data did not perform better than selecting the same number of SNPs at random from all SNPs discovered in Sami. Nearly half (46%) of the Sami SNPs with a mMAF of 0.1 are not present in the HapMap dataset. Among sites overlapping between Sami and HapMap populations, 18% are not tagged by the European American (CEU) HapMap tagSNPs, while 43% of the SNPs that are unique to Sami are not tagged by the CEU tagSNPs. These results point to serious limitations in the transferability of common tagSNPs to capture random sequence variation, even between closely related populations, such as CEU and Sami.

Linkage disequilibrium between microsatellite markers in the Swedish Sami relative to a worldwide selection of populations.

The pattern of linkage disequilibrium (LD) is affected by a number of factors, including population demography. High LD is seen in populations with a relatively limited and constant size, presumably because of genetic drift. We have examined the extent of LD among over 300 genome-wide pattern microsatellite loci in 29 populations from around the world. The pattern of LD varied between populations, with a larger extent of LD in populations with limited size relative to larger populations. In addition, the LD between 88 less well-spaced microsatellite markers from 10 different genomic regions was examined in the Sami compared with the general Swedish population. For these markers, increased LD extending up to 5 Mb was detected in the Sami. The amount of LD also differed between the chromosomal regions. The amount of LD in the Sami makes this population suitable for the mapping of complex genetic traits.