Related Experiment Video
Updated: May 8, 2026

Hypoxia Alters miRNAs Levels Involved in Non-Mendelian Inheritance of Autism Spectrum Disorder in Mice
Published on: July 11, 2025
Graduated effects of high-altitude hypoxia and highland ancestry on birth size
Rudy Soria1, Colleen G Julian2, Enrique Vargas1
1Instituto Boliviano de Biología de Altura, La Paz, Bolivia.
Background:
We present a cohort of ca. 25,000 birth records from Bolivia of men and women who are currently adults. We used this cohort to test the hypothesis that high altitude reduces birth weight and that highland ancestry confers graduated protection against this effect.
Methods:
Birth records were obtained from obstetric clinics and hospitals in La Paz (3,600 m) and Santa Cruz (420 m). Only singleton, healthy term (>37 wk) pregnancies of nonsmoking mothers were included. Andean, Mestizo, or European ancestry was determined by validated analysis of parental surnames.
Results:
High altitude reduced body weight (3,396 ± 3 vs. 3,090 ± 6 g) and length (50.8 ± 0 vs. 48.7 ± 0 cm) at birth (P < 0.001). Highland ancestry partially protected against the effects of high altitude on birth weight (Andean = 3,148 ± 15 g; Mestizo = 3,081 ± 6 g; and European = 2,957 ± 32 g; trend P < 0.001) but not on birth length. The effects of high-altitude pregnancy on birth size were similar for male and female babies.
Conclusion:
High altitude reduces birth weight and highland native ancestry confers graduated protection. Given previous studies linking reduced birth weight with increased risk of cardiovascular disease, further study is warranted to test whether adults from high-altitude pregnancy are at increased risk of developing cardiovascular disease.
Related Concept Videos
Nature and Nurture
Heritability
Factors Affecting Respiration
Polygenic Traits
Biological Influences on Intelligence
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
