M. S. Mesa

Population relationships in the Mediterranean revealed by autosomal genetic data (Alu and Alu/STR compound systems).

The variation of 18 Alu polymorphisms and 3 linked STRs was determined in 1,831 individuals from 15 Mediterranean populations to analyze the relationships between human groups in this geographical region and provide a complementary perspective to information from studies based on uniparental markers. Patterns of population diversity revealed by the two kinds of markers examined were different from one another, likely in relation to their different mutation rates. Therefore, while the Alu biallelic variation underlies general heterogeneity throughout the whole Mediterranean region, the combined use of Alu and STR points to a considerable genetic differentiation between the two Mediterranean shores, presumably strengthened by a considerable sub-Saharan African genetic contribution in North Africa (around 13% calculated from Alu markers). Gene flow analysis confirms the permeability of the Sahara to human passage along with the existence of trans-Mediterranean interchanges. Two specific Alu/STR combinations-CD4 110(-) and DM 107(-)-detected in all North African samples, the Iberian Peninsula, Greece, Turkey, and some Mediterranean islands suggest an ancient genetic background of current Mediterranean peoples.

In search of the pre- and post-neolithic genetic substrates in Iberia: evidence from Y-chromosome in Pyrenean populations.

The male‐mediated genetic legacy of the Pyrenean population was assessed through the analysis of 12 Y‐STR and 27 Y‐SNP loci in a sample of 169 males from 5 main geographical areas in the Spanish Pyrenees: Cinco Villas (Western Pyrenees), Jacetania and Valle de Arán (Central Pyrenees) and Alto Urgel and Cerdaña (Eastern Pyrenees). In the Iberian context, the Pyrenean samples present some specificities, being characterizeded by a high proportion of chromosomes R1b1b2‐M269 (including the usually uncommon R1b1b2d‐SRY2627 and R1b1b2c‐M153 types) or I2a2‐M26 and low proportions of other haplogroups. Our results indicate that an old pre‐Neolithic substrate is preponderant in populations of the whole Pyrenean fringe. However, AMOVA revealed a high level of substructure within Pyrenean populations, partially explained by drift effects as well as by the signature of an ancient genetic differentiation between Western and Eastern Pyrenees.

Secular changes in stature and biacromial and bicristal diameters of young adult Spanish males

Measurements of stature and biacromial and bicristal diameters were obtained for two samples of young adult male university students, one from 1901 to 1919 and the other from 1989 to 1991. Means and standard deviations were calculated for each measurement and for three indices. Significant positive trends in stature and biacromial and bicristal diameters were apparent between the two samples: 7.3 cm (4.4%), 3.6 cm (9.9%), and 3.4 cm (12.5%), respectively. The results for stature were compared with other Spanish samples from the beginning of the century to the present. These comparisons also showed positive secular changes, although the differences among samples may have been conditioned by regional variations in socioeconomic conditions, industrialization, and so on, all of which complicate the interpretation of the magnitude of changes in Spain. In summary, the results show a positive secular trend in body dimensions, and this can be related to the improvement in living conditions in Spain, especially during the last 40 years.

Body composition of rural and urban children from the Central Region of Spain

Body composition components are considered in a cross-sectional sample of 2564 children (age range 6-14 years) from Central Spain. The sample was divided depending on rural or urban residence. Weight, and skinfold at the triceps, biceps, subscapular and suprailiac site were measured. Body composition was represented by percentage fat (%F), lean body mass (LBM), fat mass (FM) and sum of skinfolds (SSK). Sex differences were found to be highly significant for all variables and rural-urban differences were small. Rural boys show slightly larger fat content, in %F, FM and SSK, than their urban peers, but significant (p < 0.05) differences appear only for SSK. No statistically significant environmental effect was found for LBM. The improvement of living conditions, the urban influence on the rural area and the degree of urbanization of the urban settlement are suggested as the main determinants influencing obtained results.

Dermatoglyphics of inhabitants of Alberche/Tormes valley (Sierra de Gredos-Central Spain): I. Finger pattern types and pattern intensity

The incidence of dermatoglyphic finger patterns and pattern intensity in a sample of school children from the Alberche/Tormes valley (northern slope of the Sierra de Gredos, Central Spain) are described. Significant bilateral differences for the overall finger pattern incidence are found in both sexes. The differences between sexes are also statistically significant, except for the left hand. The Pattern Intensity Index significantly differs between hands of males only, and the sex differences are not significant. Variation ranges for fingertip patterns and pattern intensity were constructed using published data of 69 male and 62 female series drawn from the whole of the Iberian Peninsula. The overall incidence of fingertip patterns and the Pattern Intensity Index locate the studied population near the middle of the corresponding variation ranges. The only exception is the case of arches, for which Alberche/Tormes is close to the minimum value of the range of variation. A more detailed comparison of 10 male and 10 female series from the Spanish northern and southern plateaus and from the Spanish region of Extremadura was done with R‐matrix analysis. The series compared include those from the northern slope (Alberche/Tormes valley, this study) and the southern slope (Tiétar valley) of the Sierra de Gredos. The observed degree of dermatoglyphic differentiation between these two series may be explained by taking into account both the role of the Sierra de Gredos as a biological barrier limiting gene flow and the evolutionary stability of dermatoglyphics.

Weight and height percentiles calculated by the LMS method in Argentinean schoolchildren. A comparative references study

Abstract Background: The Argentinean population is characterized by ethnic, cultural and socio-economic diversity. Aim: To calculate the percentiles of weight-for-age (W/A) and height-for-age (H/A) of schoolchildren from Argentina employing the LMS method; and to compare the obtained percentiles with those of the international and national references. Subjects and methods: Anthropometric data of 18 698 students (8672 girls and 10 026 boys) of 3–13 years old were collected (2003–2008) from Buenos Aires, Catamarca, Chubut, Jujuy, La Pampa and Mendoza. Percentiles of W/A and H/A were obtained with the LMS method. Statistical and graphical comparisons were established with the WHO (international reference) and with that published by the Argentinean Paediatric Society (national reference). Results: Differences in W/A and H/A, regarding the references, were negative and greater at the highest percentiles and in most of the age groups. On average, the differences were greater for boys than girls and for national than international references. Conclusion: The distribution of weight and height of schoolchildren, coming from most regions of the country, differs from those of national and international references. It should be advisable to establish a new national reference based on internationally recognized methodological criteria that adequately reflect the biological and cultural diversity of the Argentinean populations.

THREE Y-CHROMOSOME STR FREQUENCIES IN A POPULATION FROM EQUATORIAL GUINEA (CENTRAL AFRICA)

Specimens were collected from unrelated apparently healthy males, blood donors from Equatorial Guinea (Central Africa). DNA was extracted from blood specimens using a bloodclean DNA purification Kit (Biotools) and typed in an ALF-Sequencer (Pharmacia). DYS19 alleles were determined according to protocols and allelic ladders kindly supplied by Peter de Knijff (1). Primers for DYS389I and DYS389II were synthesized according to Schultes et al. (2). PCR conditions for these two systems were modified as follows: a first denaturation step at 94°C 3 min; 5 cycles of 94°C 15 s, 58#x00B0;C 20 s, 72#x00B0;C 20 s, 34 cycles of 94#x00B0;C 15 s, 54#x00B0;C 20 s, 72#x00B0;C 20 s. Amplification products were typed with allelic ladders from our laboratory. Frequencies were calculated for all the systems through the gene counting method and gene diversity was estimated according to Nei (3).

Variability of six STR loci in populations from Central Spain.

Allele frequency distributions of six short tandem repeat (STR) loci, HUMTH01, HUMFES/FPS, HUMTPOX, HUMVWF/A31, HUMF13B, and HUMLPL, were determined in a population (101 individuals) of the Vera-Jerte region in West Central Spain. Amplified products were electrophoresed on denaturing polyacrylamide gels and silver-stained. The exact test demonstrated that none of the six loci deviated from Hardy-Weinberg equilibrium. R-matrix analysis in relation to other European samples agrees well with genetic distance results of Reynolds et al. (1983). Comparisons show that our population comes reasonably well within the range of variation of other European samples, and that the representation of these samples on the genetic map indicates a close relation between geographical location and distribution in the diagram.

Anthropometric parameters in screening for excess of adiposity in Argentinian and Spanish adolescents: evaluation using receiver operating characteristic (ROC) methodology

Abstract Background: Various anthropometric parameters have been proposed for defining overweight in adolescence, but few studies have evaluated their diagnostic accuracy in comparative terms, using samples from different regions. Aim: To compare the performance of anthropometric parameters in determining the excess of adiposity in Argentinian and Spanish adolescents. Subjects and methods: The sample is composed of 1781 Argentinian and 1350 Spanish subjects, aged 12–17 years. Excess adiposity was defined as percentage BF in the 90th percentile or higher. ROC curves established the validity of parameters to define excess adiposity. Results: Descriptive statistics showed differences between the Argentinian and Spanish samples. ROC curves indicate that all the parameters analysed had, in the Spanish and Argentinian samples, a positive and elevated association with excess of adiposity. The waist-to-height ratio had the highest value of the area under ROC curve (AUC), while conicity index and waist-to-hip ratio had the lowest. Conclusions: Differences exist with respect to size and body composition between the Argentinian and Spanish samples. ROC curves reflect a general pattern of variation. Waist-to-hip ratio and conicity index are less desirable in the diagnosis of excess adiposity and the most desirable is waist-to-height ratio.

Development of subcutaneous fat in Spanish and Latin American children and adolescents: Reference values for biceps, triceps, subscapular and suprailiac skinfolds

Subcutaneous fat skinfolds represent a reliable assessment instrument of adiposity status. This study provides current percentile references for four subcutaneous skinfolds (biceps, triceps, subscapular, suprailiac) applicable to children and adolescents in Spain and in Latin American countries where data are scarce. The design consisted of a cross-sectional multicenter study performed with identical methods in 5 countries (Argentina, Cuba, Mexico, Spain and Venezuela). Total sample comprised 9163 children and youths (boys 4615 - girls 4548) aged 6-18 years, healthy and without apparent pathologies. Percentiles 3, 5, 10, 25, 50, 75, 90, 95 and 97 were calculated by the LMS method. Sexual dimorphism was assessed using the t-test and age differences with ANOVA. Normalized growth percentile references were obtained according to sex and age for each skinfold. The mean values of four skinfolds were significantly greater in girls than boys (p<0.001) and, in both sexes, all skinfolds show statistical differences through age (p<0.001) with different magnitudes. Except triceps in girls, peaks between 11 and 12 years of age are more noticeable in boys than in girls. Although the general model of growth is known, the skinfold measurements show variability among populations and differences of magnitude are presented according to the analyzed population. Therefore, these age and sex-specific reference percentile values for biceps, triceps, subscapular and suprailiac skinfolds, derived from a large sample of Spanish and Latin American children and adolescents, are a useful tool for adiposity diagnosis in this population for which no reference values were available.