Estimadores de mezcla amerindia basados en métodos serológicos y moleculares / Amerindian admixture estimation based on serological and molecular methods

Background: Amerindian admixture is an important parameter to consider in epidemiological studies in American countries, to make a proper selection of cases and controls. Aim: To compare Amerindian admixture estimates obtained using ABO*A and ABO*O blood group alleles and ancestral identity markers (AIMs) in the mixed Chilean population. Subjects and Methods: Amerindian admixture rates were determined in 720 Chilean volunteers residing in Arica and born in the 15 regions of the country, using ABO*O and ABO*A alleles and 40 AIMs selected from more than 500,000 single nucleotide polymorphisms (SNP´s). Results: Mean admixture estimates obtained using ABO*O and ABO*A alleles and AIM s were 35, 47% and 48% respectively. There was concordance in estimates, with the exception of the admixture based on ABO*O allele and AIMs. Conclusions: In Chile, Amerindian admixture estimates obtained using ABO*A could be used as an alternative to AIMs in justified cases provided the sample size is reasonably large.

Variables perinatales de recién nacidos de madres Aymara sugieren adaptación genética a la altura / Perinatal variables from newborns of Aymara mothers suggest a genetic adaptation to high altitude

Background: Studies performed in Andean populations living in high altitude, indicate that the reduced availability of oxygen could be associated to both a fetal growth retardation and a lower birth weight. These variables are predictive of morbidity and mortality during the first year of life. Aim: To study perinatal variables of newborns of mothers living at contrasting altitudinal levels, harboring different degrees of Aymara ancestry. Subjects and Methods: Review of medical records of 5,295 women whose deliveries occurred between February 2004 and August 2010. Information was obtained on place of residence, grouped into two categories: coast (150 to 3,000 m) and high plateau (3,000 to 4,300 m), ancestry was estimated using number of Aymara surnames that were homologated to percentages of Amerindian admixture, gestational age, birth weight, height, head circumference and obstetric variables. Results: Gestational age showed a tendency to increase and birth weight, height and head circumference to decrease with altitude of residence. Only weight reached statistical significance. Women with Aymara ancestry gave birth to children with a significantly higher gestational age, weight and cranial circumference. Conclusions: Altitude of residence is related to a decrease in perinatal variables that proved to be less pronounced in newborns of mothers with a higher degree of Aymara ancestry. Results suggest a genetic adaptation to hypoxia that could be related to candidate genes linked to the capture, transport or utilization of oxygen.