A genome-wide association study identifies novel gene associations with facial skin wrinkling and mole count in Latin Americans.

BACKGROUND: Genome-wide association studies (GWASs) have identified genes influencing skin ageing and mole count in Europeans, but little is known about the relevance of these (or other genes) in non-Europeans. OBJECTIVES: To conduct a GWAS for facial skin ageing and mole count in adults < 40 years old, of mixed European, Native American and African ancestry, recruited in Latin America. METHODS: Skin ageing and mole count scores were obtained from facial photographs of over 6000 individuals. After quality control checks, three wrinkling traits and mole count were retained for genetic analyses. DNA samples were genotyped with Illumina's HumanOmniExpress chip. Association testing was performed on around 8 703 729 single-nucleotide polymorphisms (SNPs) across the autosomal genome. RESULTS: Genome-wide significant association was observed at four genome regions: two were associated with wrinkling (in 1p13·3 and 21q21·2), one with mole count (in 1q32·3) and one with both wrinkling and mole count (in 5p13·2). Associated SNPs in 5p13·2 and in 1p13·3 are intronic within SLC45A2 and VAV3, respectively, while SNPs in 1q32·3 are near the SLC30A1 gene, and those in 21q21·2 occur in a gene desert. Analyses of SNPs in IRF4 and MC1R are consistent with a role of these genes in skin ageing. CONCLUSIONS: We replicate the association of wrinkling with variants in SLC45A2, IRF4 and MC1R reported in Europeans. We identify VAV3 and SLC30A1 as two novel candidate genes impacting on wrinkling and mole count, respectively. We provide the first evidence that SLC45A2 influences mole count, in addition to variants in this gene affecting melanoma risk in Europeans.

Attention-deficit hyperactivity disorder involves differential cortical processing in a visual spatial attention paradigm.

OBJECTIVE: Inattention is undoubtedly one of the main characteristics of Attention-deficit hyperactivity disorder (ADHD). Nevertheless, a growing corpus of evidence shows that not all attentional processes are affected in this condition. This study aimed to explore the distribution of attentional resources in children with ADHD via a spatially shifted double-oddball visual task. METHODS: We recorded event-related potentials (ERPs) for all visual stimuli. Subjects were instructed to allocate attention in a specific area of visual space while ignoring all stimuli presented outside. Ten male children (age: 9-14; mean = 11.6 +/- 2.1) who met DSM-IV criteria for the ADHD combined subtype participated in the study, along with ten age- and sex-matched healthy controls (9-14; mean = 11.2 +/- 2.3). RESULTS: ADHD subjects showed late differential cortical responses to initially suppressed irrelevant stimuli. The amplitude of early N1-P1 components were mainly modulated by stimulus location and showed no significant differences between groups, but a late P300-like positivity was clearly evoked in the ADHD group by peripheral stimuli. CONCLUSIONS: These results suggest that ADHD may not compromise the early attentional spatial filter but rather entails a different distribution of attentional resources at later stages of cortical processing. Perhaps these differences may be attributable to individual differences in attentional mechanisms. SIGNIFICANCE: ADHD may not affect initial focusing of visual attention but rather the allocation of processing resources in later stages.

Origin and evolutionary relationships of native Andean populations.

This paper represents an effort to explore the origin and the evolutionary relationships of native Andean populations using a multidisciplinary approach. Archeological and linguistic evidence is briefly reviewed. A genetic distance analysis among major linguistic groupings and among Andean and Amazonian native populations, together with information obtained from archaeological and linguistic sources was used to generate a migration model. It is suggested that in the late Pleistocene a group of nomadic hunters entered South America through the Isthmus of Panama and split afterwards into two groups, one moving southward into the central and south Andean areas and after crossing the Colombian, Equador and Peruvian highlands to people northwestern Argentina, the open park country of east Brazil and the Argentine Pampas. The second group migrated eastwards into Venezuela and Guyana and later southward, peopling the Brazilian Amazon. Following available waterways the Amazonian Indians expanded east and west arriving probably at the eastern slopes of the Andes some 3,500 years ago. It is hypothesized that present day Andean natives are descendants of the Amazonian groups that migrated eastwards.

2,3-Diphosphoglycerate and night vision.

Recovery of night vision at altitude has been examined in relationship to changes of 2,3,diphosphoglycerate (DPG). It appears that, if DPG influences night adaptation, its effect is small. Inter-individual variability is large, both in terms of DPG and performance on the MESOP, the device used to measure dark adaptation.

Genetic marker variation in coastal populations of Chile.

Gene frequencies for nine genetic marker systems are presented for the following Chilean coastal populations: Paposo, Carelmapu, Laitec and Ukika. Historical and anthropological data suggest the presence of descendants of the Amerindian populations, specifically of Changos, Cuncos, Chonos and Yamanas in these populations. Results indicate that the studied groups maintain an important aboriginal genetic composition. According to Amerindian admixture estimates, the genetic isolation of coastal populations is lower than that of inland populations, suggesting that proximity to the sea facilitated gene flow. Genetic distances and dendrograms were obtained for these populations and another four Chilean Indian populations. Results agree with expectations, taking geographic isolation and non-aboriginal admixture into account.

[Determinants of arterial blood pressure in a negative Andean population]. / Determinates de la presión arterial en una población andina nativa.

The joint effect of adiposity, high altitude, age and indigently on systolic and diastolic blood pressure is studied in an Indian population living at high altitude in Northern Chile. Adiposity (Quetelet's index), accounted for the highest percentage of explained variability, followed by high altitude and age. Indigently was shown to have an insignificant effect on blood pressure, indicating that Andean aboriginal populations did not differ genetically from lowland populations with respect to this variable.

The heredity of human alcohol abuse: myths and facts.

Myths and facts concerning the heredity of human alcohol abuse are discussed in this article. Familial aggregation, adoption studies, twin concordances, marker gene associations and, finally, recent biochemical and genetic evidence are examined critically. It is concluded that with the exception of a possible protective action of the ALDH2 gene in Japanese there is a lack of clear cut evidence with respect to the direct participation of genetic factors in human alcoholism.

Gene geography of South America: testing models of population displacement based on archeological evidence.

Gene frequencies for 13 marker systems are used to construct synthetic gene frequency maps of South America. The surfaces generated using the first three principal components exhibit clines which validate models of population displacement based on archeological data and a previous analysis of craniometrical variation.

Craniometrical variation among South American prehistoric populations: climatic, altitudinal, chronological, and geographic contributions.

The independent contributions of climate, altitude, chronology, and geographic location of archeological sites to craniometrical variation are analyzed in a sample of 1,119 skulls from South America. Geographic location is responsible for the highest proportion of craniometrical variation, followed by climate and altitude. It is concluded that geographic isolation has partially prevented gene flow from counterbalancing craniometrical microdifferentiation produced by founder effect.

Peopling of Andean South America.

Archeological, craniometrical, and genetic information is utilized to reconstruct possible migration routes used in the peopling of Andean South America. Special emphasis is given to the elaboration of craniometrical isoline maps and its application in testing models of population displacement based on archeological data. A genetic distance analysis among linguistic groupings complements the conclusions based on archeological and craniometrical information.

A note on the presence of blood groups A and B in pre-Columbian South America.

The results of ABO typing in Chilean mummies, a review of published South American paleoserological studies and a systematic discrepancy of admixture estimates based on ABO and Gm genes support the hypothesis that Andean pre-Columbian populations possessed the A (and perhaps the B) gene in small frequencies.

[Genetic composition of the Chilean population: the population from San Pedro de Atacama]. / Composicion genética de la población chilena: los atacameños de la comuna de San Pedro de Atacama.

This work describes the genetic composition of atacameños from San Pedro de Atacama. The results show that a) the contribution of non-indigenous genes is relatively low, in relation to the spanish immigration period. b) the Hardy-Weinberg genetic disequilibrium for MNSs system should have biological implications c) the variant for esterasa D enzyme may be the same found in other chilean populations.

[Alcoholism and heredity. A critical update]. / Alcoholismo y herencia. Una actualizacion critica.

The etiology of alcoholism is under constant revision. This work critically examines the accumulated evidence on the degree of genetic determination of alcoholism, aiming to provide an updated view of the problem. The methodological aspects of studies performed in families, twins and adopted siblings are analyzed. The associations of alcoholism with genetic markers and diseases are reviewed, including the negative correlation between alcoholism and an aldehyde dehydrogenase variant in Japanese subjects. The association between marker genes, specially the HLA system, with organic damage and the future projection of these studies are mentioned.

[Paleodemography in mummies of prehispanic populations from Africa]. / Paleodemografía en momias de poblaciones prehispánicas de Arica.

Mummies' demographic information of 10 prehispanic cultures that developed in the Arica region of Chile about 7000 years ago is analyzed and related to the present population structure. A paleoepidemiological analysis supports a relationship between cultural development and demographic structure. In chronological sequence, 4 demographic patterns can be distinguished: 1) archaic, a mature population with the highest life expectancy and the lowest dependence from prehispanic populations; 2) later archaic, a population in demographic explosion with its larger fraction under 15 years of age, elevated fertility rates and the greatest prehispanic dependence; 3) andean, a transition population with moderate fertility rates and dependence index; and 4) modern, an aging population with the highest proportion over 45 years of age and the highest life expectancy. The present demographic analysis may help to understand the relationships among disease, individual and culture from the perspective of genetic epidemiology.

[Genetics of addictive disorders]. / Genética de los desórdenes adictivos.

Given the spectacular advances of genetics during the last five years, it seems appropriate to revisit the important subject of genetics of alcoholism and substance abuse. In recent studies alcohol abuse was shown to have an hereditability of roughly 38%, whereas psychostimulant and opiate use exhibit hereditabilities of 11 to 45%. The hereditability of smoking was found to be around 50%. There is a strong comorbidity between alcoholism and smoking. More than 80% of alcoholics smoke cigarettes in the U.S.A. Other genetic methods such as linkage analysis, allele sharing methods, association studies and analysis of inbred, transgenic and gene-knockout rodents, have partially agreed in showing that the 5HT-1B serotonin receptor and the DRD1, DRD2 and DRD4 dopamine receptors, as well as the dopamine transporter DAT, play an important role in behaviors related to alcoholism and substance abuse. Some neurochemical markers, as for example monoamine oxidase and adenylate cyclase have also been implicated in addictive disorders. The aldehyde dehydrogenase allele ALDH2*2 has a protective effect against alcoholism. Two whole genome linkage studies have shown linkage to chromosomal regions that are in the proximity of the DRD4 dopamine receptor, the GABA receptor gene cluster and the alcohol dehydrogenase gene cluster.

The Chipaya of Bolivia: Dermatoglyphics and ethnic relationships.

Dermatoglyphic data on 15 traits (digital arches, digital radial loops, digital ulnar loops, digital whorls, I loops, Ir loops, H loops, H loops, III loops, IV loops, mainline C absence, total ridge count, a-b ridge count, atd angle, and mainline index) are presented for 141 Chipaya Indians of Bolivia. Ethnic relationships of these Indians to nine South American Indian tribes (Alacaluf, Atacameño, Aymara, Cashinahua, Chácobo, Chama, Chané, Quechua, and Sirionó) are explored by means of a genetic distance analysis using 21 alleles. Genetic distances are complemented with linguistic and geographic distances between the Chipaya and the other tribes. Genetic distances were found not to be significantly correlated with linguistic and geographic distances. Combining the information available, it is concluded that the Chipaya are most likely ethnically related to the Arawak speakers of the tropical forest.

A collation of marker gene and dermatoglyphic diversity at various levels of population differentiation.

The use of dermatoglyphic traits to describe interpopulational diversity among human populations at various levels of differentiation is compared with similar analysis of gene frequency data by means of nonparametric methods employing distance matrices and dendrograms, and by a partition of total variability into its between and within population components. Congruence of dermatoglyphics and gene markers appears to vary with level of population differentiation -- the association remains insignificant until racial level of differentiation is considered. Different pitfalls of the data used are mentioned. The interpretation of these findings is discussed by comparison with other non-human studies.

[Genetic composition of Chilean population: rural communities of Elqui, Limari and Choapa valleys]. / Composición genética de la población chilena: las comunidades rurales de los valles de Elqui, Limarí y Choapa.

BACKGROUND: The population that inhabits the semiarid Northern zone of Chile arose from ethnic admixture between aborigines, Spanish conquerors and the influx, during the XVII century, of foreign aboriginal workers and a minority of African slaves. AIM: To study the phenotypic frequencies of 15 genetic markers among populations inhabiting valleys in the Northern zone of Chile and to estimate the percentage of indigenous, African and Caucasian admixture in these populations. MATERIAL AND METHODS: Throughout five different field works, blood samples were obtained from 120 individuals living in the Elqui valley, 120 individuals living in the Limari valley and 85 living in the Choapa valley. Blood groups, erythrocyte enzymes, plasma proteins and HLA markers were typified. RESULTS: In the populations studied, the contribution of non indigenous genes was low in relation with the time elapsed since the Spanish invasion. The Hardy-Weinberg disequilibrium for MNS system would have microevolutive implications. The admixture percentages in these valleys confirm ethnic and historic information. The variation of the enzyme esterase D is identical to that of other Chilean populations. CONCLUSIONS: The phenotypic and genetic frequencies in the three populations studied and different admixture of indigenous genes is inversely proportional to the geographic distance from Santiago, in Central Chile.