Genetic study of the population of Tenerife (Canary Islands, Spain): protein markers and review of classical polymorphisms

North African-Mediterranean HLA genetic contribution in a population of the kidney transplant waiting list patients of Canary origin (Gran Canaria)

The peopling of the Canary Islands has been widely debated. The mitochondrial DNA and Y-chromosome data support the idea of a Berber genetic origin coming from the North of Africa (maternal) and a later contribution of the Spanish invaders (paternal). The frequencies of the HLA class II alleles from the Tenerife Island (another Canary Island) have previously been published, postulating a Berber and Atlantic/Iberian contributions to the current population. The HLA class I and class II allele frequencies, haplotype frequencies and phylogenetic comparisons were performed in 215 unrelated individuals from Gran Canaria Island (belonging to the kidney transplant waiting list), with at least three generations of ancestors from Canary Islands, in order to study the different ethnical HLA contributions to the genetic background of the Canary Islanders. Results showed the presence of a compound HLA haplotype of putative Phoenician-Berber origin, A*33:01-C*08:02-B*14:02-DRB1*03:01-DQB1*02:01, likely coming from the combination of haplotypes A*30:02-C*05:01-B*18:01-DRB1*03:01-DQB1*02:01 and A*33:01-C*08:02-B*14:02-DRB1*01:02-DQB1*05:01 of North African (probably Berber) and West Asian Mediterranean (probably Phoenician) origins, respectively. The latter haplotypes and others from the same origin (Berber/Phoenician) are also present in the population studied. Besides, other contributions from the North of Europe, North England-Iberian (Atlantic contribution), and Western Europe/Mediterraneans (Spanish colonization) are also discussed. These data conclude that the current genetic background of the Canary Islands inhabitants has been generated over the years by different ways with an original Phoenician-Berber substrate and several genetic contributions generated in different invasions.

Evidence of Helminth Infection in Guanche Mummies: Integrating Paleoparasitological and Paleogenetic Investigations

The Guanches, ancient inhabitants of the Canary Islands, Spain, practiced mummification of their dead. A paleoparasitological and paleogenetic analysis was conducted on mummified bodies (n = 6) (AD 1200, Cal BP 750) belonging to the Guanche culture from Gran Canaria Island. Coprolite and sediment samples (n = 19) were removed from below the abdominal region or sacral foramina. The samples were rehydrated in 0.5% trisodium phosphate solution for 72 hr at 4 C, and the paleoparasitological investigation was conducted by spontaneous sedimentation method and microscopic examination. The results revealed the presence of well-preserved eggs of Ascaris sp., Trichuris trichiura , Enterobius vermicularis , and hookworms. Ancient DNA was extracted from sediment samples to elucidate the ancestry of the mummies and for molecular detection of Ascaris sp. infection. Results of paleogenetic analysis demonstrated Ascaris sp. infection using 2 molecular targets, cytb and nad1. The mtDNA haplotypes U6b, U6b1, and HV were identified, which confirmed records of Guanche ancestry. The excellent preservation of Guanche mummies facilitated the paleoparasitological and paleogenetic study, the results of which contribute to our knowledge of Guanche culture and their health status.

[PI*S and PI*Z alpha 1-antitrypsin deficiency: estimated prevalence and number of deficient subjects in Spain]

BACKGROUND AND OBJECTIVE

Alpha-1-antitrypsin deficiency (AATD) is an hereditary disorder with increased risk of pulmonary emphysema and chronic liver diseases in children and adults. Since it is possible currently in Spain to apply alpha-1-antitrypsin replacement therapy to AATD patients, the objective of this study was to calculate the total number of subjects affected by PIS and PIZ AATD, and its phenotypic distribution. SUBJECTS, MATERIAL AND METHOD: Selection of published studies on allelic frequencies PIS and PIZ according to the following criteria: a) alpha-1-antitrypsin phenotyping performed by isoelectrofocusing; b) rejection of "screening studies"; c) statistic precision factor score of 5, and d) samples representative of the Spanish general population.

RESULTS

Four out 34 cohorts were selected. Mean gene frequencies (per 1,000) were: 104 (95% confidence interval [CI], 96-113) for PI*S and 17 (95% CI, 14-21) for PI*Z. These data indicated that it would exist in Spain 9,173,181 AATD subjects (95% CI, 9,167,966-9,178,398), with the following phenotypic distribution: 7,358,263 (95% CI, 6,696,222-8, 072,328) for PIMS; 1,222,041 (95% CI, 972,767-1,539,805) for PIMZ; 436,023 (95% CI, 369,057-514,244) for PISS; 144,827 (95% CI, 107,227-195,038) for PISZ; and 12,026 (95% CI, 7,788-18,493) for PIZZ. The global prevalence was 1 out of 4.4 individuals, with the following distribution: PIMS 1/5; PIMZ 1/33; PISS 1/92; PISZ 1/278; and PIZZ 1/3,344.

CONCLUSIONS

AATD is a frequent but underdiagnosed disease in Spain.

Palatine torus in the pre-conquest inhabitants of the Canary Islands

An unusually high frequency of palatine torus in prehistoric Canary Islands skeletal remains is investigated in terms of population origins, evolutionary forces (gene flow and genetic drift) and environmental effects. Palatine torus frequencies (percent presence) are compared between the Canary Islands sample and skeletal samples from proposed ancestral regions, including northwest Africa, northeast Africa, sub-Saharan Africa, southern Europe, northern Europe and western Asia. The frequency of palatine torus is much higher in the Canary Islands sample (23.8%) than in samples from Northern and sub-Saharan Africa (1.8-6.1%), southern Europe (7.5%) and western Asia (2.1%), but is much lower than in the sample from northern Europe (57.4%). Because biological and archaeological evidence provide strong support for a northwest African origin for indigenous Canary Islands populations, the relatively high occurrence of palatine torus in the Canary Islands populace cannot be explained by an alternative ancestry; rather, it may be best explained by either evolutionary forces such as genetic drift or gene flow, or by environmental forces, such as hard chewing or a heavy dependence on marine foods. Genetic drift and gene flow seem less likely, since frequencies of other dental traits known to be under strong genetic control do not differ greatly between the prehistoric Canary Islands and northwest African samples. Environmental factors such as diet seem the most likely explanation and may include heavy consumption of marine foods, which has been implicated in torus formation.

Genetic epidemiology of alpha-1 antitrypsin deficiency in southern Europe: France, Italy, Portugal and Spain

Alpha-1-antitrypsin deficiency (AAT deficiency) is one of the most common serious hereditary disorders in the world because it affects all major racial subgroups worldwide and there are at least 120.5 million carriers and deficient subjects worldwide. This genetic disease is related to a high risk for development of jaundice in infants, liver disease in children and adults, and pulmonary emphysema in adults. Moreover, AAT-deficiency carrier phenotypes (PiMS and PiMZ) and deficiency-allele phenotypes (PiSS, PiSZ, and PiZZ) are suspected to make subjects susceptible to a variety of other adverse health effects. As there is a limited database on the number of individuals affected by this disease worldwide, the authors of the present report collected data on control cohorts in genetic epidemiological studies published in the peer-reviewed literature worldwide. The data collected were used to estimate the numbers of carriers and deficiency-allele combinations for the two most common defective alleles, namely PiS and PiZ, in over 58 countries worldwide. The present report focuses on the distribution of the PiS and PiZ deficiency alleles in France, Italy, Portugal, and Spain. The total number of individuals at risk for adverse health effects were as follows: 9, 101, 739 in France; 4, 289, 566 in Italy; 2, 659, 241 in Portugal; and 8, 903, 773 in Spain. The geographical distribution of individual control cohorts and estimates of the numbers of carriers and deficiency-allele phenotypes in each of these four southern European countries are shown in individual tables and maps. This report will be followed by other reports on the remaining countries in Europe, as well as worldwide.

A predominant European ancestry of paternal lineages from Canary Islanders

We genotyped 24 biallelic sites and 5 microsatellites from the non-recombining portion of the Y chromosome in 652 males from the Canary Islands. The results indicate that, contrary to mtDNA data, paternal lineages of the current population are overwhelmingly (>90%) of European origin, arguing for a highly asymmetric pattern of mating after European occupation. However, the presence of lineages of indisputable African assignation demonstrates that an aboriginal background still persists (<10%). On the basis of distribution and dating of some of these lineages we derived a genetic perspective of settlement processes of the archipelago in two stages, congruent with anthropological, archaeological and linguistic findings.

Canary islands-north African population affinities: measures of divergence based on dental morphology

This investigation addresses two related questions about the origins and biological affinities of the Canary Islands' aboriginal inhabitants. First: With which North African populations do the pre-conquest inhabitants of the Canary Islands have their greatest affinities? Second: Does inter-island biological variability among the Canary Islanders, as has been suggested by other researchers (Hooton 1925, Schwidetzky 1963), imply that potentially different founding populations remained distinct during the pre-conquest period? This study employs dental morphology data derived from pre-conquest skeletons to answer these questions. Non-metric dental traits appear to be controlled by polygenic systems with a low to moderate environmental contribution to the resulting phenotype (Berry 1978, Harris & Bailit 1980, Nichol 1990) and can thus be assumed to reflect genetic relationships. The dental morphology of a sample of Canary Islanders (n = 397) is compared to that of Northwest African samples of Algerian Shawia Berbers (n = 26), Kabyle Berbers (n = 32), Bedouin Arabs (n = 49) and Punic Carthaginians (n = 28) as well as to six samples from Northeast Africa (n = 307) included for the purpose of understanding Canary Islanders' affinities within a wider context. The analysis employs 28 dental traits, quantifying differences in their expression among the various samples through a summary statistic, CAB Smith's Mean Measure of Divergence (MMD). The MMD analysis indicates that the Canary Island sample is most similar to the four samples from Northwest Africa: the Shawia Berbers, Kabyle Berbers, Bedouin Arabs and Carthaginians, less similar to the three Egyptian samples and least like the three Nubian samples. An intra-island comparison among samples from La Gomera, Gran Canaria and Tenerife reveals low, insignificant MMD values in all cases, implying that inter-island dental morphology differences are not so great as to require hypotheses of separate founding populations.

IL4-R1 (5q31-q33) and FcepsilonRI-betaca (11q13) markers and atopy: a case/control study in a spanish population

BACKGROUND

Rhinoconjunctivitis and bronchial asthma are atopic diseases with a high prevalence in the Canary Islands (Spain). Given that the most prevalent allergen is the house-dust mite Dermatophagoides pteronyssinus, early detection of genetically susceptible subjects would allow the application of preventive measures. The objective was to investigate the possible association of IL4-R1 (chromosome 5q31-q33) and FcepsilonRI-betaca (chromosome 11q13) markers with the atopic disease in our population.

METHODS

We performed a case/control study in which patients were recruited on the basis of diagnosis of rhinoconjunctivitis and/or bronchial asthma, and positive skin prick test to D. pteronyssinus. Analysis of IL4-R1 and FcepsilonRI-betaca microsatellites was carried out by PCR and electrophoresis in acrylamide gels.

RESULTS

We have not found evidence of association between IL4-R1 and FcepsilonRI-betaca markers and atopic disease in our population. In addition, these markers have shown a high percentage of homozygosis.

CONCLUSIONS

IL4-R1 and FcepsilonRI-betaca markers have not proved to be useful genetic markers for linkage or association studies in our population.

Alpha1-antitrypsin Pi phenotypes S and Z in Spain: an analysis of the published surveys

The aim of the present study was to review published surveys on allelic frequencies S and Z in Spanish populations to evaluate the validity of the reported data. Thirty-four studies published since 1965 were retrieved by MEDLINE, Index Medicus and consultations with experts. The criteria for studies selection were (i) sample size > or = 250 individuals; (ii) alpha-1-antitrypsin phenotyping determination performed by means of crossed antigen-antibody electrophoresis or isoelectrofocusing; (iii) S and Z reported outcomes with an upper 95% CI smaller than mean + 2 SD, a lower 95% CI smaller than mean - 2 SD, and the following ratio: 100 x (95%CI upper limit - 95%CI lower limit)/allelic frequency, for both S and Z, included in the mean +/- 2 SD interval. Thirteen out of 34 surveys retrieved complied with the proposed criteria for S gene frequency analysis and 11 fulfilled the criteria for Z. The greatest frequency for S type is in the north-west of the country (149 alleles per 1000 in Galicians natives), while frequencies in the rest of the country are approximately 100 alleles per 1000. The greatest frequency for Z type has been reported in newborn infants from Valladolid (20.8) and in a randomly selected general population of Asturias (19.7). In the rest of Spain, Z frequencies range from 1.5 to 15 alleles per 1000 genes.

Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands

Recently, the Canary Islands have become a focus for studies of the colonization and the diversification of different organisms. Some authors have considered Canarian endemisms as relicts of Tertiary origin, but new molecular data suggest a general pattern of continental dispersion followed by in situ speciation. Recent phylogeographic studies are revealing variants of the simple stepping-stone colonization model that seems to hold for many Hawaiian groups. Many factors can generate deviations from such a pattern: the stochastic nature of colonization, competitive exclusion, phylogenetic constraints on adaptive evolution and extinction. An understanding of island colonization and diversification can best be developed from an ecosystem level synthesis as more data for the Canarian archipelago come to hand.