Genetic analysis of chest dimensions in a high altitude Tibetan population from upper Chumik, Nepal

Studies of high altitude Andean natives generally report large chest dimensions relative to sea level groups, while results from studies of Himalayan populations are not consistent. One hypothesis is that this may represent different adaptive patterns in the two geographic areas. The purpose of this study is to explore the determinants of chest dimensions by assessing the genetic components of variation in chest width and chest depth in a Tibetan population resident at 3250-3560 m in Upper Chumik, Nepal. Data were available for 608 individuals (298 males, 310 females) aged 2-79 years; 471 individuals could be assigned to 134 pedigrees containing between 2 and 10 people with data. The remaining 137 individuals were treated as independents. A maximum likelihood variance decomposition method was used to assess the genetic components of each trait. Growth in chest width and depth was modeled as a linear function of age until an asymptote, at which growth was considered to reach a plateau. Both chest width and chest depth were moderately heritable (h width2 = 0.50 ± 0.10, h depth2 = 0.49 ± 0.08). There was a significant genetic correlation (0.43 ± 0.13) between chest width and depth, suggesting that some genes have pleiotropic effects on both traits. The observed significant genetic components of these morphological traits indicate that there is potential in this population for genetic adaptation of chest dimensions to the high altitude environment. © 1993 Wiley-Liss, Inc.