RESUMO
Studies performed in the Andean plateau, one of the highest inhabited areas in the world, have reported that reduced availability of oxygen is associated to fetal growth retardation and lower birth weight, which are established predictors of morbidity and mortality during the first year of life. To test this hypothesis, perinatal variables of neonates born at the Juan Noé Hospital of Arica, Chile, were analyzed in relation to altitude of residence and Aymara ancestry of their mothers. The study population comprised the offspring of 5,295 mothers born between February 2004 and August 2010. Information included birth weight, height, head circumference, gestational age, altitude of residence and socioeconomic status, and was obtained from medical records. Mother´s ancestry was assessed based on surnames which were linked to percentages of Aymara admixture estimates relying on 40 selected ancestry informative markers. After correcting for the effect of multicollinearity among predictor variables, neonates born to mothers with an increased component of Aymara ancestry showed significantly higher birth weight and height at sea level, a marginally significant (p-value 0.06) decrease of birth weight and a significant decrease of height with altitude in comparison with the offspring of mothers with low Aymara ancestry. Since observed tendencies are suggestive of a possible genetic adaptation to hypoxia of the Chilean Aymara, we discuss briefly preliminary evidence related to fetal oxygen transport, particularly polymorphisms in the promoters of the HBG1 and HBG2 genes that are modulators of HbF synthesis, obtained in this ethnic group.
Assuntos
Altitude , Peso ao Nascer/fisiologia , Tamanho Corporal/fisiologia , Adaptação Fisiológica , Adolescente , Adulto , Chile , Feminino , Hemoglobina Fetal/metabolismo , Idade Gestacional , Cabeça/fisiologia , Humanos , Hipóxia , Indígenas Sul-Americanos/genética , Recém-Nascido , Masculino , Mães , Polimorfismo Genético , Regiões Promotoras Genéticas , Análise de Regressão , Estudos Retrospectivos , Classe Social , Adulto Jovem , gama-Globinas/genéticaRESUMO
A positive secular trend for stature and weight is evident in rural Aymara-speaking Indians of the Parinacota Province (>3,000 m) in the northern Chilean Andes. The study is based on two cross-sectional growth surveys carried out in 1972 and 1987. In the survey of 1972, which was undertaken by other authors, a sample of 190 individuals was considered. The 1987 survey, performed by the present author, comprises a sample of 170 Indians. Both children and adults of each sex, ages 6-29 years, are included. Secular comparisons of age-grouped means indicate a secular increase in stature and weight in Aymara children, adolescents, and adults in the Parinacota Province between 1972 and 1987. The Aymara tend to be taller and heavier in 1987. The estimated secular increase for stature is 2.1 cm/decade for males and 1.8 cm/decade for females. For weight, the increase is 2.3 kg/decade for males and 1.5 kg/decade for females. In all cases, growth gains tend to be greater in males than in females. The body mass index also increases slightly. The secular changes in stature and weight are statistically significant in both sexes. From additional nutritional data on the Aymara samples compared, it is concluded that the observed secular increases might primarily reflect improved food supply over the past two decades. Am. J. Hum. Biol. 10:607-617, 1998. © 1998 Wiley-Liss, Inc.