RESUMO
The single-nucleotide polymorphisms (SNP) ILDR1 rs2332035 has shown a high statistical association with presbycusis (hearing loss with age or age-related hearing impairment (ARHI)), according to genetic association studies in European populations. However, linked markers have not been surveyed. Here linkage disequilibrium (LD) of markers in ILDR1, in relation to rs2332035, is explored in the 2504 individuals from the 1000Genomes database. Of the 920 SNPs retrieved, 10 showed strong LD (r2= 0.8) in Europeans and Latin Americans, which are proposed here as candidate markers for both control-case association and cause-effect studies in both populations.
Assuntos
Polimorfismo de Nucleotídeo Único , Presbiacusia , Receptores de Superfície Celular , Humanos , Estudos de Associação Genética , Genótipo , Desequilíbrio de Ligação , Presbiacusia/genética , Receptores de Superfície Celular/genéticaRESUMO
The hepatic lipase plays a central role in the lipid metabolism, catalyzing the hydrolysis of phospholipids, monoglycerides, diglycerides, and triglycerides, and acyl-CoA. It is also implied in the conversion of very low-density lipoprotein and intermediate density lipoprotein to low density lipoproteins. As a consequence, the gene encoding the hepatic lipase (LIPC) is associated with several diseases derived from the imbalance of lipids that are in general derived from the interaction between life styles and genetic architecture. Therefore, it is interesting to understand more about the characteristics of the microevolutionary processes affecting genes that, like LIPC, have a role in nutrition and lipid metabolism in human populations. We explored the selection signatures on LIPC in 26 populations, detecting three regions under recent positive selection.
Assuntos
Lipase/genética , Fígado/enzimologia , Frequência do Gene , Genética Populacional , HumanosRESUMO
The genetic trait of lactase persistence (LP) evolved as an adaptation to milking pastoralism in the Old World and is a well-known example of positive natural selection in humans. However, the specific mechanisms conferring this selective advantage are unknown. To understand the relationship between milk drinking, LP, growth, reproduction, and survival, communities of the Coquimbo Region in Chile, with recent adoption of milking agropastoralism, were used as a model population. DNA samples and data on stature, reproduction, and diet were collected from 451 participants. Lactose tolerance tests were done on 41 of them. The European -13,910*T (rs4988235) was the only LP causative variant found, showing strong association (99.6%) with LP phenotype. Models of associations of inferred LP status and milk consumption, with fertility, mortality, height, and weight were adjusted with measures of ancestry and relatedness to control for population structure. Although we found no statistically significant effect of LP on fertility, a significant effect (P = 0.002) was observed of LP on body mass index (BMI) in males and of BMI on fertility (P = 0.003). These results fail to support a causal relationship between LP and fertility yet suggest the idea of a nutritional advantage of LP. Furthermore, the proportion of European ancestry around the genetic region of -13,910*T is significantly higher (P = 0.008) than the proportion of European ancestry genome-wide, providing evidence of recent positive selection since European-Amerindian admixture. This signature was absent in nonpastoralist Latin American populations, supporting the hypothesis of specific adaptation to milking agropastoralism in the Coquimbo communities.
Assuntos
Agricultura , Etnicidade/genética , Evolução Molecular , Lactase/genética , Animais , Índice de Massa Corporal , Chile , Feminino , Fertilidade , Frequência do Gene , Estudos de Associação Genética , Cabras , Haplótipos , Humanos , Intolerância à Lactose/genética , Masculino , Leite , Fenômenos Fisiológicos da Nutrição , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
OBJECTIVES: Lactase persistence (LP) is a genetic trait that has been studied among different countries and ethnic groups. In Latin America, the frequencies of this trait have been shown to vary according to the degree of admixture of the populations. The objective of this study is to better understand the relationship between this genetic trait and dairy intake in a multiethnic context through a synthesis of studies conducted in four regions of Chile. METHODS: Genotypes frequencies for the SNP LCT-13910C>T (rs4988235) and frequency of dairy consumption were obtained from four populations: Polynesians from Easter Island (Rapanui); Amerindians (Mapuche) and Mestizos from the Araucanía region; urban Mestizos from Santiago; and rural Mestizos from the Coquimbo region. Genetic differentiation and association between milk consumption and genotype frequencies were estimated. RESULTS: Genetic differentiation between Native and Mestizo populations was significant; the LP frequency in Mapuche and Rapanui was 10% and 25%, respectively, whereas among the Mestizos, LP frequency was near 40%. Dairy intake was below the nutritional recommendations for the four groups, and extremely below recommendations among the indigenous populations. Association between milk intake and LP was found in Santiago and Rapanui populations. CONCLUSIONS: Although the frequency of LP varies among the populations according to their degree of admixture, dairy consumption was very low across the populations. Given that the association between milk consumption and expected phenotype was found only in two of the populations analyzed, it seems that lactase non-persistence (LNP) is not the only cause for dairy avoidance. Thus, it is suggested that SES and cultural preferences are likely affecting dairy consumption.
Assuntos
Laticínios , Ingestão de Alimentos , Etnicidade/genética , Frequência do Gene , Genótipo , Lactase/genética , Polimorfismo de Nucleotídeo Único , Animais , Chile , Humanos , Lactase/deficiência , PolinésiaRESUMO
BACKGROUND: Alleles involved in inefficient (ADH1B2*2 and ALDH2*2) or efficient (SNP6, ADH4 gene) alcohol metabolism may influence the risk of alcoholism. Alcoholism susceptibility has been classified as protector and risk-dependence phenotypes, associated with inefficient and efficient alcohol genetic metabolizing variants, respectively. AIM: To investigate the possible association between genetic protective and risk-dependence variants and alcohol intake patterns. MATERIAL AND METHODS: Saliva DNA samples were obtained and the AUDIT (Alcohol Use Disorders Identification Test) questionnaire was applied to 210 university students aged between 18 and 25 years old. RESULTS: No statistically significant association between protective or risk-dependence genetic variants and alcohol pattern intake was detected. However, new categories of alcohol intake patterns-not included in the AUDIT questionnaire-were identified. CONCLUSIONS: No association between the protector and risk-dependence phenotypes and patterns of alcohol consumption was detected in this sample of students.
Assuntos
Consumo de Bebidas Alcoólicas/genética , Fenótipo , Polimorfismo de Nucleotídeo Único , Adolescente , Adulto , Consumo de Bebidas Alcoólicas/metabolismo , Chile , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Estudantes , Universidades , Adulto JovemRESUMO
Background: Alleles involved in inefficient (ADH1B2*2 and ALDH2*2) or efficient (SNP6, ADH4 gene) alcohol metabolism may influence the risk of alcoholism. Alcoholism susceptibility has been classified as protector and risk-dependence phenotypes, associated with inefficient and efficient alcohol genetic metabolizing variants, respectively. Aim: To investigate the possible association between genetic protective and risk-dependence variants and alcohol intake patterns. Material and Methods: Saliva DNA samples were obtained and the AUDIT (Alcohol Use Disorders Identification Test) questionnaire was applied to 210 university students aged between 18 and 25 years old. Results: No statistically significant association between protective or risk-dependence genetic variants and alcohol pattern intake was detected. However, new categories of alcohol intake patterns-not included in the AUDIT questionnaire-were identified. Conclusions: No association between the protector and risk-dependence phenotypes and patterns of alcohol consumption was detected in this sample of students.
Assuntos
Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem , Consumo de Bebidas Alcoólicas/genética , Fenótipo , Polimorfismo de Nucleotídeo Único , Consumo de Bebidas Alcoólicas/metabolismo , Chile , Predisposição Genética para Doença , Estudantes , UniversidadesRESUMO
Lactase persistence (LP) occurs at a very low frequency in indigenous populations from Latin America, offering an opportunity to understand the relationship between this genetic trait and patterns of dairy consumption. Here, the frequency of LP is analyzed from Mapuche and -an adjacent- mestizo population inhabiting the Araucanía region. In addition to genotyping for LP, participants were surveyed in relation to general perception and consumption habits of dairy products. Low LP frequency (10%) and very low dairy intake was found among the Mapuche population as compared with Mestizo populations inhabiting Chile. The survey reported that the main reasons for avoidance of dairy were the gastrointestinal symptoms after dairy intake and cultural dietary habits. The interaction between low LP genotype frequency, low dairy intake, and sociocultural determinants is here discussed in the light of their potential health outcomes.
Assuntos
Etnicidade/genética , Comportamento Alimentar , Indígenas Sul-Americanos/genética , Lactase/genética , Intolerância à Lactose/genética , Antropologia Física , Laticínios , Humanos , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
We examined 103 nucleotide sequences of the HIV-1 env gene, sampled from 35 countries and tested: I) the random (neutral) distribution of the number of nucleotide changes; II) the proportion of bases at molecular equilibrium; III) the neutral expected homogeneity of the distribution of new fixated bases; IV) the hypothesis of the neighbor influence on the mutation rates in a site. The expected random number of fixations per site was estimated by Bose-Einstein statistics, and the expected frequencies of bases by matrices of mutation-fixation rates. The homogeneity of new fixations was analyzed using χ² and trinomial tests for homogeneity. Fixations of the central base in trinucleotides were used to test the neighbor influence on base substitutions. Neither the number of fixations nor the frequencies of bases fitted the expected neutral distribution. There was a highly significant heterogeneity in the distribution of new fixations, and several sites showed more transversions than transitions, showing that each nucleotide site has its own pattern of change. These three independent results make the neutral theory, the nearly neutral and the neighbor influence hypotheses untenable and indicate that evolution of env is rather highly selective.
Assuntos
Sequência de Bases/genética , Evolução Molecular , Genes env/genética , HIV-1/genética , Seleção Genética/genética , Mutação , FilogeniaRESUMO
The subfamily Xylocopinae has been recognized as the most basal lineage within the family Apidae, comprising four tribes; Allodapini, Ceratinini, Xylocopini and Manueliini. Relationships among the tribes are not well resolved with morphological data. In particular, Manueliini and Xylocopini have each been placed as the most basal lineage in separate analyses of the subfamily. While relationships within each tribe, excepting Manueliini, have been investigated using molecular data, these data have not been applied to examine the relationships among tribes, which remain controversial. Here we present results of molecular phylogenetic analyses using sequences of CoI, Cytb and EF-1alphaF1 from members of the four tribes of Xylocopinae. We used available data from other studies in combination with data generated for the three species of Manueliini. Competing phylogenetic hypotheses regarding the alternate positions proposed to Manueliini and Xylocopini were evaluated through statistical tests. The basal position of either Manueliini or Xylocopini has contrasting implications on the evolutionary history of nest architecture, which mediates the potential for contact between adult and immature individuals. Our results indicate that Manueliini is the most basal lineage of Xylocopinae, in agreement with an evolutionary transition from nests having completely sealed cells to nests lacking cells. A nest structure with closed cells prevents physical interactions between adult and immature stages, whereas an open structure provides the opportunity for interactions that may play an important role in the emergence of sociality.
Assuntos
Abelhas/genética , Evolução Molecular , Comportamento de Nidação , Filogenia , Animais , Abelhas/classificação , DNA Mitocondrial/genética , Análise de Sequência de DNARESUMO
We examined 103 nucleotide sequences of the HIV-1 env gene, sampled from 35 countries and tested: I) the random (neutral) distribution of the number of nucleotide changes; II) the proportion of bases at molecular equilibrium; III) the neutral expected homogeneity of the distribution of new fxated bases; IV) the hypothesis of the neighbor infuence on the mutation rates in a site. The expected random number of fxations per site was estimated by Bose-Einstein statistics, and the expected frequencies of bases by matrices of mutation-fxation rates. The homogeneity of new fxations was analyzed using χ2 and trinomial tests for homogeneity. Fixations of the central base in trinucleotides were used to test the neighbor infuence on base substitutions. Neither the number of fxations nor the frequencies of bases ftted the expected neutral distribution. There was a highly signifcant heterogeneity in the distribution of new fxations, and several sites showed more transversions than transitions, showing that each nucleotide site has its own pattern of change. These three independent results make the neutral theory, the nearly neutral and the neighbor infuence hypotheses untenable and indicate that evolution of env is rather highly selective.